Worms and Germs Blog : Animal Health & Diseases : University of Guelph : Ontario Veterinary College : Zoonotic Diseases : Guelph, Hamilton, Ontario

While it shouldn't come as a surprise considering other studies, a recent study in PLoS One (O'Brien et al 2012) has caused a bit of a stir in the US. This study, headed up by Dr. Tara Smith's research group in Iowa, looked for methicillin-resistant Staphylococcus aureus (MRSA) in retail pork. They bought pork from different stores in Iowa, Minnesota and New Jersey, and tested it for the presence of MRSA. They focused on pork because MRSA can be found widely in pigs internationally, including in the US.

Not surprisingly, they found MRSA. Overall, they tested 395 pork samples from 36 stores, including both "conventional" pork (300 samples) and "alternative" pork (95 samples). The latter consisted of samples labelled "raised without antibiotics" or "raised without antibiotic growth promotants." MRSA was found in 6.6% of samples; 6.3% of conventional pork samples and 7.4% of alternative pork samples.

When they looked at the MRSA types that were present, 27% were the ST398 "livestock-associated" MRSA that's most commonly found in pigs.  However, like our earlier Canadian studies, they found common "human-associated" MRSA strains more often. These strains can also be found in pigs, albeit less commonly than ST398, and it's unclear whether meat contamination with these strains comes from pigs or from people who handle the meat throughout the processing chain.

The fact that there was no difference between conventional and antibiotic-free pork isn't surprising to me, although it catches some people off-guard because of some basic over-assumptions about the relationship between antibiotics and MRSA in food animals. We can find MRSA quite commonly on both regular and antibiotic-free farms.  While it's reasonable to assume that antibiotics were a key factor in driving the emergence of MRSA in pigs, there's not much evidence showing that ongoing antibiotic use is an important factor in determining whether MRSA is present on specific farms or in specific pigs. One potential explanation is that in order to control infections, farms that stop using antibiotics start using other substances such as zinc in feed to help control overgrowth of certain intestinal bacteria, and these compounds may be just as effective at selecting for certain resistant bugs as classical antibiotics. That's just one possible explanation, but it shows how complex the issue of antibiotic-resistance is, and it shows that simply saying "stop using antibiotics," without really looking at the overall problem, won't necessarily reduce MRSA.

What does the presence of MRSA in food mean? Who knows? MRSA is a pretty high profile bug, and with good reason, because it's a very important cause of infection in people. A key aspect of MRSA in food is that cooking food will kill the bacteria (as well as many of the other harmful bacteria that often contaminate raw meat). So proper attention to food safety, including thorough cooking, cleaning of surfaces, prevention of cross-contamination and hand hygiene, should greatly reduce any risk (the problem is a lot of these things aren't usually done very well).

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No, not gravy made from bearded dragons (a type of reptile), but foodborne Salmonella with a link to the reptile.

Reptiles are an important source of Salmonella, which is why standard guidelines recommend that high-risk people (e.g. children less than 5 years of age, elderly individuals, people with compromised immune systems, pregnant women) not have contact with reptiles or have them in the house. A report in Zoonoses and Public Health (Lowther et al 2011) highlights another possible risk.

The report describes a Salmonella outbreak that was traced back to a potluck dinner. Nineteen cases were identified, 17 primary cases (people that attended the dinner) and two secondary cases (household members of people that attended the dinner). Overall, 29% of people that attended the dinner got sick. A further 18 people had some intestinal disease but strictly speaking didn't fit the definition for a case (however it is suspected that they were part of the outbreak). Salmonella subspecies IV (a type mainly associated with reptiles) was isolated from the stool of five people, confirming the occurrence of an outbreak.

As is typical, food consumption history was evaluated. Sixteen of the 17 primary cases reported consuming turkey gravy, which was a statistically higher proportion than that of people who did not get sick. The gravy was made at the private home of a person who didn't attend the dinner. This was the only home of the people involved where reptiles were kept. Two healthy bearded dragons lived in the house, in a terrarium in the living room.

The investigation focused on the reptiles, since the Salmonella strain found is typically associated with reptiles, and the turkey (the source of the gravy) had no evidence of Salmonella contamination based on testing. Samples from the environment of the household where the gravy was made were collected, and two types of Salmonella were identified. One of these Salmonella types (Salmonella Labadi, which was different from the outbreak strain) was isolated from one of the bearded dragons, as well as the inside and outside of the terrarium glass, other terrarium surfaces, surfaces around the terrarium, the bathroom sink drain and kitchen sink drain.

A common question that comes up when people have reptiles and high risk people in the house is "If I don't take the critter out of the cage, I should be ok, right?" Unfortunately, that's not true. Human Salmonella infections have been clearly identified in situations where reptiles don't leave the terrarium because (as was the case here), while the reptile may not leave the terrarium, Salmonella often does.

The person who made the gravy said that the bearded dragons had not been out of the terrarium when food was being prepared. A child was responsible for feeding the reptiles and cleaning the terrarium, and was supposed to use the bathroom for terrarium cleaning. However, it was reported that the reptiles' dishes "might have" been cleaned in the kitchen sink during the the day period when food was being prepared for the party.

The overall conclusion was that this outbreak "probably resulted from environmental contamination from bearded dragon faeces." It's a reasonable conclusion. Even though the same Salmonella strain wasn't found in the reptile, it makes sense because the reptiles were the most likely source of environmental contamination in the household, and that was the most likely source of the foodborne contamination. Reptiles can shed various Salmonella strains and they can shed intermittently. It takes multiple samples over time to get a real idea of the scope of Salmonella shedding, and I assume that one or both of these reptiles were shedding the outbreak strain at some point.

How can something like this be prevented, since the standard recommendation of having high risk people avoid contact with reptiles doesn't apply to this type of situation?

• Good hygiene practices should be used when handling reptiles and their environments. In particular, there should be proper attention to hand hygiene after contact with reptiles or their cages.
• Reptiles should not be allowed in the kitchen. Ever.
• Food and water bowls should not be cleaned in kitchen sinks. Terrariums should not be cleaned in kitchen sinks. Ideally, they shouldn't be cleaned in bathroom sinks either. (If possible they should be cleaned outdoors with a hose.)
• Good food handling practices are critical. Here, gravy wasn't re-heated to a high enough temperature to kill the contaminating Salmonella. Adequate re-heating would have prevented this outbreak.

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Last summer, I wrote about rabies in person from New Jersey, and now the full report about the case is available.

The unfortunate victim was a 73-year-old Haitian women. She initially went to an emergency room with a complaint of right shoulder pain, chest pain, headaches and high blood pressure. Difficulty swallowing was also noted when she was given pain medications, but she declined further testing and was discharged. It's not surprising that rabies wasn't considered at this point, although I doubt she was asked about animal contact or animal bites as a routine history question.

The next day, the woman went to two different emergency rooms, complaining of shortness of breath, spasms, hallucinations and balance problems. A cause was still not readily apparent, and over the next couple of days, her condition deteriorated, with development of more neurological abnormalities including tremors and mild seizures. Encephalitis (inflammation of the brain) was diagnosed, and a range of potential causes were ruled out. A nuchal skin biospy was collected for rabies testing but she was declared brain dead by the time results were obtained.

The strain of rabies that was identified most closely matched a canine rabies virus variant from a person in Florida who acquired rabies in 2004 while in Haiti. Upon further investigation, a cousin recalled that the person had been bitten by a dog in Haiti a few months earlier. The bite wasn't considered severe and medical attention wasn't sought.

As an almost invariably fatal infection but an almost completely preventable disease with proper medical care, education is a key aspect of rabies control, and that's where most of the breakdowns occur. This person didn't seek medical attention after the bite, because the bite wasn't too severe. Unfortunately, mild bites can transfer rabies just like severe bites, and any bite needs to be investigated as a potential source of rabies, particularly in highly endemic areas.

Canine rabies is a major problem internationally, accounting for tens of thousands of human deaths each year. Canine rabies has been eradicated in the US, meaning the canine rabies virus strain is no longer circulating. That doesn't mean dogs in the US can't get rabies, since they can be infected with various wildlife strains, but there is not a circulating pool of canine rabies virus like in some other regions. Canine rabies is still endemic in Haiti, although there have been efforts to control it through education and vaccination of dogs and cats in the country (where less than 50% of dogs and cats are vaccinated).

People living and traveling to rabies-endemic regions like Haiti need to be aware of the potential risk of rabies and consider any dog bite a possible rabies exposure. Similarly, healthcare workers need to query animal exposure and animal bites as a routine practice, since as with this case, rabies can be hard to diagnose initially.

(click image for source)

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It seems like pet bite articles come in waves, with a recent cluster showing the variable quality in advice that's available.

Often, they are holiday "filler" articles that provide some basic useful information but overall are of limited use or even harmful based on their very superficial approach. They often mention rabies, get a quick quote from a veterinarian or someone in public health, but don't emphasize the potential problems that can occur with even apparently minor bites. The thing that often raises my ire is the common statement about watching the bite and going to a doctor if your limb swells up or has pus oozing out, without talking about the need for proper post-bite care to actually prevent that from happening.

Anyway, I came across a couple of better articles recently, that get some good information across in a nice, readable manner. One, an article in "The Herald News" entitled "Cat bites always require check by doctor", gets a very important point across quickly.

The news story details the saga of the PJ, a 13-year-old cat, and his owner. PJ bit the woman on the arm causing a seemingly minor wound, but by the next day, her arm was red and swollen, necessitating a round of intravenous antibiotics and four days in hospital. In the article, Gail Steele, an infection prevention nurse, states "Cat bites.. must always be considered medical emergencies. This is especially true when they occur in the hand because that area has a richer blood supply...Their sharp little teeth are like little needles, and they inject bacteria right into soft tissue..."

This is a pretty extreme example of what can happen after a cat bite, but it's far from rare. It's not really clear whether this person's infection would have been prevented with normal practices. Bites over certain sites, like the hand, foot, joints, tendon sheaths and prosthetic devices, and bites to young kids, elderly individuals and people with compromised immune systems typically require prophylactic antibiotics.

If this was actually a bite over the arm, as reported, antibiotics might not have been given, even though cat bites are much higher risk for infection than dog bites. However, the key is that bites should be assessed so proper determination can be made about the need for antibiotics. All infections won't be prevented but appropriate medical care should reduce the risk and also allow for adequate consideration of whether rabies exposure might be a concern.

There's a sad end to this article, as PJ bit his owner again a few months later. The bite was over the shin and, given her previous problems, antibiotics were provided. However, the owner still ended up with an abscess that required surgical intervention and took months to heal. (Whether this person has really bad luck, whether PJ has a particularly bad mix of bugs in his mouth or whether the owner has an unidentified problem with her immune system is unclear, but back-to-back severe infections is a major issue, especially with a cat that is prone to biting.) The woman's daughter ended up taking PJ home with her, but after another unprovoked bite, he was euthanized.

Cat bites aren't always this bad, and in fact, most don't result in complications. However, that's not to downplay the potential problems. When you consider how often cats bite, how often cat bites are not properly cared for because they appear to be minor, and the ability of a cat bite to inoculate bacteria deep into the tissues, it's easy to see how bad things can happen. Reducing the risk of cat bite infections involves a few basic steps:

• Reducing bites. Good handling and training (of both cats and people) can reduce the likelihood of bites. This is particularly important with kids, who may be bitten through rough or excessive handling of a cat.
• Bite first aid. Prompt cleaning of the wound can reduce bacterial contamination. Thorough cleaning with soap and water can have a big impact on the likelihood of infection.
• Medical care. Bites over certain sites or to certain individuals (see above) almost always require antibiotics. There's less consensus over other types of bites, but getting medical care is a good idea in any case to determine if there are any factors that indicate a need for antibiotics.
• Rabies avoidance. Every bite should be reported to public health so the rabies aspect can be covered. The biting animal needs to be identified and observed for 10 days. If it's healthy after 10 days, it couldn't have been shedding rabies virus. If the biting animal cannot be identified, it's likely that post-exposure treatment for rabies will be required.

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A South Carolina woman has been identified as the first case of human rabies in the state in the past 50 years. Very little information has been released, including whether or not she is still alive. Unfortunately, the odds are quite low that she survived. Successful treatment of a Wisconsin girl in 2004 using a radical new protocol was accompanied by much optimism for treatment of this disease, which at the time was described as invariably fatal. While a few other survivors have been reported, rabies is now often referred to as almost invariably fatal, since the protocol has not been the panacea that it was hoped to be, and death is still the typical outcome.

In the latest case, exposure to a bat in the home a few months earlier was the suspected source of infection. This is a common source of exposure and a typical time frame. Few details are presented, so it's not clear whether the woman was known to have been bitten by the bat or whether that's suspected for some other reason (such as lack of other possible sources).

This is another indication of the care that needs to be taken around bats. While human rabies is fortunately very rare in Canada and the US (it causes tens of thousands of deaths each year worldwide, mainly from dogs in a few developing countries), bats are an important source of exposure. Any encounter with a bat needs to be accompanied by a determination of whether there is a risk of rabies exposure. Anyone bitten by a bat should try to make sure the bat is caught and tested for rabies, because otherwise there's no way to prove it wasn't rabid, and post-exposure treatment would be indicated.

Image: Bat bites can be very dangerous, because they carry the risk of rabies transmission, but they can be so small that they may not even be detected. (Image source: http://agrilife.org/batsinschools/responding-to-a-bat-bite/)

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The focus of this blog is companion animals, but sometimes I just can't resist commenting on other areas, and this one's too good to pass up.

Today's Morbidity and Mortality Weekly Reports, published by the CDC, describes Campylobacter jejuni infection in two men. Campylobacter is a zoonotic bacterium that causes diarrhea (and sometime severe complications) in people after it's ingested. It's usually a foodborne disease, but any  method that leads to the bacterium reaching the mouth and being swallowed can result in to infection. This report describes a rather unusual method of infection.

This summer, the Wyoming Department of Health investigated two cases of C. jejuni infection. Both people worked on a local sheep ranch and got sick at the same time. Both had typical campylobacteriosis disease with diarrhea, cramps, fever, nausea and vomiting. One was hospitalized but both recovered. The interesting part is how they got infected. It turns out the men were involved in a multiday "event" to castrate and dock tails of 1600 lambs. Ten other people were also involved and they didn't get sick. The difference between these two and the other ten? The two infected men used their teeth to castrate some of the lambs. Animal welfare issues aside, this is just stupid. (I doubt anyone's looking at this but these idiots shouldn't be allowed to care for animals.) I don't see how anyone with an iota of common sense wouldn't think this is a bad idea in the current day and age.  A very long time ago, apparently the "bit and spit" technique of castrating lambs (see photo, click for source) was relatively common practice.  But like so many things that people used to do, there are much better (and safer, and infinitely more hygienic) ways of doing this nowadays.

Hopefully, they learned their lesson. Additionally, hopefully the farm owner takes some responsibility to make sure their personnel don't act like idiots and that someone investigates the animal cruelty aspect.

Photo: In "the old days" during castration of lambs, after opening the scrotal sac with a sharp blade, the testicles were often removed using the teeth, because it was faster than attempting to do so with an instrument.  This technique is (almost) no longer practiced (except for at least two men in Wyoming, apparently). Photo source: http://old-photos.blogspot.com (used with permission)

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Staphylococcus schleiferi doesn't get much respect. Most of the attention gets paid to Staphylococcus aureus (because MRSA, the methicillin-resistant version, is such a high profile pathogen in humans and it can be transmitted between people and pets) and S. pseudintermedius (because it's a leading cause of infection and MRSP, the methicillin-resistant type, is spreading very quickly and widely in dogs).

Staphylococcus schleiferi is another Staphylococcus species that can cause various infections in dogs, particularly skin and ear infections. It's often overlooked, or more specifically, unnoticed. The problem is it takes some effort to differentiate it from other staph. This species is relatively unique in that it has two distinct subtypes - S. schleiferi coagulans and S. schleiferi schleiferi. The first one is very similar to S. pseudintermedius, and not all diagnostic labs go through the trouble of trying to distinguish one from the other. So there may actually be a lot of S. schleiferi infections that get mistakenly diagnosed as S. pseudintermedius. The second subtype is coagulase-negative (whereas S. pseudintermidius, S. aureus the first subtype of S. schleiferi are all coagulase-positive) and most diagnostic labs don't do any identification of coagulase negative staph. As a result, we only have a superficial understanding of it and its epidemiology.

A recent study from the University of Pennsylvania (Cain et al., J Am Vet Med Assoc 2011) that looked at 225 dogs with S. schleiferi infections has provided some insight into this perhaps not-so-unusual bug. Some highlights:

Ear infections and skin infections accounted for 87% of cases.

• That's expected, since these are very common types of infections for any kind of staph.

Allergic skin disease was the most common underlying disease.

• That's also not surprising. Most staph infections occur secondary to some underlying problem or procedure (e.g. surgery). This shows the importance of taking the time and effort to diagnoses and control allergic skin disease, in order to help prevent infections before they occur.

57% of S. schleiferi  isolates were methicillin-resistant.

• Ugh! I'm not very surprised but it's scary how often we see methicillin-resistance in some staphylococci, because of the complications it can cause with treatment. Methicillin-resistant staph infections can be hard to treat because there may be few effective antimicrobials available.

Methicillin-resistance was more common in the coagulase negative subspecies, S. schleiferi schleiferi.

• It's hard to say whether this means a lot from a clinical standpoint. In generally, coagulase negative staph are much less of a concern than the coagulase positive staph since they are less likely to cause disease. However, we don't really understand the differences between the two S. schleiferi's. If the coagulase-negative version is less able to cause disease, then a lower rate of methicillin resistance in the more concerning coagulase positive type is better than vice versa, but I'm not sure we have enough evidence to say much about this at the moment.

Treatment with a penicillin (e.g. amoxicillin), first generation cephalosporin (e.g. cephalexin) or 3rd generation cephalosporin within the preceding 30 days was associated with having methicillin-resistant S. schleiferi.

• That's not surprising and is one more piece of evidence that "routine" use of antibiotics can contribute to selection for methicillin-resistant staph. It shows how we need to focus on prudent use of antibiotics.

A question I sometimes get is whether an animal with methicillin-resistant S. schleiferi poses a risk to people. We don't really know, but the risk is probably quite limited.

• S. schleiferi coagulans infections in people are extremely rare, so this bug doesn't seem to have much of an affinity for humans.
• S. schleiferi schleiferi infections in people are more common, but it is thought that this subtype is a "human Staphylococcus." Therefore, while it can cause infections in people (usually infections in people that are already sick and/or in hospital), it probably comes from people, not animals.
• So, overall, the risk posed by infected animals is minimal. However, some S. schleiferi can be very drug resistant and you don't really want to have an infection with a multidrug resistant bacterium of any kind ("you're case is very unique" isn't something you want to hear from your doctor), so using good general infection control and hygiene practices around infected dogs makes sense.

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The scope of research that's being done these days is astounding. Somewhere, someone's working on a project that will lead to a Nobel Prize in medicine. Other research will gather less critical acclaim but still have a big impact on science. Some research is more basic but can result in important preliminary information. And some studies... well, they may have a serious side but they're not what people typically think about when envisioning medical research.

Here are a few highlights from the lesser-heralded group of people investigating bathroom behaviours:

• A study of toilet reading habits in Israeli adults (Goldstein et al. Neurogastroenterol Motil 2009) concluded that toilet reading is a common and benign habit. (I hadn't really thought of it as a potentially poor lifestyle choice, but I guess this confirms it's fine). While it involves more time spent in the bathroom, "It seems to be more for fun and not necessarily to solve or due to medical problems." (Perhaps a more relevant area of study would be hand hygiene practices by toilet readers and the impact of toilet reading on fecal contamination of reading materials.)
• A Korean group has established that frequent recreational cycling does not have a negative impact on urination or sexual function in men (Kim et al. Korean Journal of Urology 2011). Cycling enthusiasts around the world, including me, rejoice.
• Horseback riders can be similarly relieved (pardon the pun) that recreational riding isn't associated with increased risk urinary or sexual dysfunction (Alanee et al. Urology 2009).
• A study with the catchy title "Female bowel function: the real story" (Zutshi et al Dis Colon Rectum 2007) wasn't too thrilling but had tidbits such as older women and women with children report more flatulence.

What do these have to do with zoonotic or infectious diseases? Nothing, but a little potty humour lightens up the start of the work day. More "real" posts to follow.

(click image for source)

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CTV has a consumer reports segment and a recent topic involved feeding pets "natural" diets (although no one ever defined what that really means). In the report on the CTV Consumer Alert website (it's currently about the third story into the video if you just press play, or you can shortcut to it using the link below the main video window), a 26 year old cat is held up as a poster child for the health benefits of raw food. Making it to 26 is a noteworthy accomplishment for a cat, but it's far from rare, and you can't know whether the cat survived because of its diet or despite its diet. At the end of the clip, they mention he cat has kidney disease, not an uncommon problem in older cats but one that is often blamed by raw proponents on commercial foods. It's also not a condition that I'd want to see someone try to manage with a raw diet.

Anyway, the story has the typical statements (including one from a veterinarian) about how raw and "natural" diets produce a healthier animal, stronger immune system and shinier haircoat, but without citing any proof (because there is none) and with no discussion whatsoever about the potential animal and public health impacts of raw meat feeding.

Good investigations are good. Quick reports put together with little thought or consideration of the issues are just time filler. The host, Pat Foran, said in his conclusion that "natural" pet foods have less filler so there's less to come out the back end of the dog. Well, news reports comprised of filler produce the same kind of by-product.

If you are going to feed raw, at least take the time to research how to do it safely, both for your pet and your household. Raw feeding can be done in a nutritionally sound manner, but it takes time, effort and money. Some people are willing and able to do that, but if you're not, don't feed raw. Raw feeding also carries some risk of gastrointestinal disease like salmonellosis in the animal as well as exposure of people in the household to those same bugs. Certain households, particularly those with high risk individuals (e.g. elderly, infants, pregnant women, immunocompromised persons) should avoid raw feeding or only use products that have been high pressure pasteurized. There are a few commercial raw diets that are treated in this manner and these are preferable as the process should kill most relevant bacteria, reducing or eliminating the infectious disease risks to pets and people.

Like many other things in life, the key is being informed so you understand the risks and benefits, and whether recommendations made by people have any substance behind them. Too often, people make a major change like feeding raw based on a comment on a website or from another dog owner, with no clue about the issues and no effort to figure out how to do it right. That's just asking for problems.

More information about raw diets can be found on the Worms & Germs Resources page.

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Veterinarians at Michigan State University's College of Veterinary Medicine are warning of an upswing in leptospirosis in dogs in the Detroit area. More than 20 cases of leptospirosis have been reported in dogs in the Detroit area, and it's likely that many more unreported cases have occurred. Leptospirosis, a bacterial infection, can cause very serious disease, including potentially fatal renal failure. It can be vague and hard to diagnosis if people aren't thinking about the disease. The most commonly identified problem is kidney disease, and early diagnosis and treatment is critical for successful treatment.

The Leptospira bacterium can survive well in the environment, particularly in moist conditions, and dogs are often exposed through wet environmental areas that have been contaminated with leptospires from the urine of infected wildlife. The strain that has predominated in the latest Michigan cases is Leptospira Icterohemorrhagiae, a type most often associated with rats.

Prevention of leptospirosis involves avoiding exposure to the bacterium as much as possible (largely through avoiding contact with wet areas where lepto cases have been identified) and vaccination. Vaccines are available for dogs and they can reduce the incidence and severity of disease caused by four different lepto types, including Icterohemorrhagiae.  Vaccination should be considered in dogs in regions where lepto cases are identified and in dogs at increased risk of exposure based on lifestyle and travel.

(click image for source)

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Here’s a recent question I received:

 "My problem is that the raccoon broke a window, came into my house, ate the cat food and then defecated on the kitchen floor. Since they went a day without food, the cats may have eaten the few bits of food that were left behind. How can I tell if they got the roundworm?"

It’s a reasonable question given the concerns about Baylisascaris procyonis, the raccoon roundworm. However, there’s basically no risk. While it is very likely that the raccoons were shedding roundworm eggs in their feces, those eggs are not immediately infective. Ingesting a "fresh" roundworm egg isn't a risk. Eggs have to sit around in the environment for at least 11 days (typically 14-28 days) before they become infective. Therefore, unless the feces are allowed to sit around in the house for a couple of weeks, roundworm infection isn’t a concern in such a case.

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Infectious diseases are continuous challenges for animal shelters. Unfortunately, outbreaks are not uncommon. Sometimes they're the result bad luck and the inherent risks involved in bringing together  lots of animals of questionable health status from different sources. However, if you compound these risks with things like inadequate facilities, overcrowding, poor training of personnel, poor adherence to protocols, bad protocols, lack of awareness about infectious diseases and failure to get expert help early in any outbreak, the likelihood of "badness" increases.

A few shelter outbreaks are underway at the moment, and they highlight some of the infectious disease challenges posed by different diseases in animal shelters.

• The Oakville and Milton Humane Society (in Ontario) is closed because of a ringworm outbreak that's been going on since early September. Ringworm, while of limited health consequences, is an important shelter problem because it's common, highly transmissible, can be hard to control and can infect people. At last report, 22 cats were confirmed or suspected to have ringworm, along with at least four staff members. It's not clear who's coordinating the outbreak response, but hopefully they're getting good advice and they've read the comprehensive report from the Newmarket OSPCA ringworm debacle.
• 72 kittens were euthanized in the Miami-Dade County Animal Services because of "cat plague," which is a common name for feline panleukopenia. This viral disease is preventable by vaccination, but it's a serious concern in shelters were there are often lots of unvaccinated or inadequately-vaccinated cats and lots of susceptible kittens. In this shelter, all cats with clinical signs consistent with panleukopenia are being euthanized. Euthanasia is always a tough decision, but with a serious disease like this, it's a reasonable response. Outbreaks like this highlight the need for excellent infection control practices to reduce the risk of spread of pathogens like this once they make it into a shelter.
• Upper respiratory tract infections have resulted in suspension of adoptions at the Bergen County Animal Shelter in New Jersey. News reports are calling it a canine influenza outbreak, and canine flu is definitely on the list of possibilities, but it doesn't sound like it's been confirmed. Respiratory infections are a common cause of problems in animal shelters because some causes (e.g. canine parainfluenza virus, canine influenza virus) are quite transmissible. Canine flu poses extra challenges when it moves into a new area, since few if any dogs have antibodies against the virus and therefore it can spread rapidly. The report also mentions transmission by dogs not showing signs of disease. That's a problem with some infectious agents. For example, with canine flu, dogs tend to be able to shed the virus before they show signs of illness. Therefore, there's a period of a couple of days after infection but before disease where you can have a silent reservoir of infection. That's why quarantine of new admissions is critical, since it gives animals a few days to show signs of diseases they may be brewing at the time of admission. (Unfortunately, it's not easy to find space in which to quarantine an animal in an overcrowded shelter.)

A common denominator in all of these outbreaks is the potential that something could have been done differently to prevent the problem. It's possible (although unlikely) that everything that was done perfectly, however it's a rare outbreak where you can't find multiple areas for improvement. A key aspect of outbreak management is, once the crisis is over, performing an investigation of what really went wrong and why, and taking measures to reduce the chance of it happening again.

Image: Ringworm infection in a cat is not always readily apparent, but in some cases can cause obvious patches of hair loss.

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The CDC's annual animal rabies surveillance report has been published in a recent edition of the Journal of the American Veterinary Medical Association (Blanton et al 2011). It's the regular synopsis of the state of rabies in domestic animals and wildlife in the country. It contains some interesting information but few surprises. Among the highlights:

• Rabies was identified in 6154 animals in 48 US states, plus Puerto Rico. The true number of animals that died of rabies in the year would have been much higher, since not all animals (particularly wildlife) that die of rabies get tested.
• 92% of positive animals were wildlife, including raccoons (37% of cases), skunks (24%), bats (23%) and foxes (7%).
• Cats were the most commonly affected domestic animal, accounting for 4.9% of cases (303 cats), followed by cattle (1.1%), dogs (1.1%) and horses (0.6%).
• Different rabies virus variants predominated in different regions. For example, raccoon rabies virus was most common on the east coast. Different skunk rabies variants predominated in the south-central and north-central regions, along with California and Nevada. A couple of pockets of fox rabies were present in the southwest, along with one in Alaska. Mongoose variant was present in Puerto Rico. Bat variants were spread out across the country.
• Most rabid cats were from states where raccoon rabies is endemic. About 1/3 of infected cats were from Pennsylvania and New York. Texas was the leader in dog rabies, followed by Puerto Rico and Virginia.
• Two cases of rabies in humans were identified, compared to 4 in 2009. One was a migrant worker infected by a vampire bite while in Mexico. The other was a man from Wisconsin who was infected with a bat rabies strain. Both died.

Canadian and Mexican data are also reported:

• 123 cases of rabies were identified in Canada, 93% of which were wildlife. 7 (5.7%) were dogs or cats. No rabid raccoons were identified, continuing a trend that has been observed since 2009. Bats and skunks were the wildlife leaders. No people were infected.
• 357 cases were reported in Mexico. 83% were cattle, 20 were dogs. Four human cases were identified.

While rabies does not exert anywhere near the impact on people in North America compared to many other regions (where tens of thousands of people die from the disease every year), it continues to take its toll on wildlife and, to a lesser degree, domestic animals. It's also a preventable disease that can be controlled with vaccination, and human cases can effectively be eliminate by proper post-exposure treatment. Continued efforts are needed to reduce rabies in wild and domestic animal populations, for both the protection of those populations and protection of the people who may come in contact with them.

(click image for source)

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An outbreak of canine influenza is occurring in San Antonio, TX, as this virus continues its strange and unpredictable movement through the North American dog population. In an article published on a local San Antonio news website, Dr. Michele Wright, a San Antonio veterinarian, reports 20 confirmed and 70 suspected cases over the past month. It's not clear whether these are all from her clinic, nor is there any information about possible sources of the virus or the severity of disease. Dr. Wright also states that the virus has been identified in Austin and Dallas.

It's not particularly surprising that canine flu has been found in Texas. It's now been identified in at least 38 US states, as well as one Canadian province. An outbreak is not particularly surprising either in this case, because when a virus reaches a new area, it can easily cause widespread disease since it encounters a population of animals that don't have any pre-existing immunity (i.e. antibodies) against it.

What's strange about canine flu is how it has spread across North America. When it was first identified in Florida greyhounds in 2004, it seemed like it was going to spread widely across the dog population. It spread quickly at greyhound tracks and in clusters in Florida and in other states, but it's subsequent spread across the continent was quite patchy - it caused only localized outbreaks in different states, instead of the catastrophic continent-wide epidemic that was anticipated. Whether this relates to the amount and type of direct contact between dogs (e.g. dogs are only infectious for a short period of time and an infected dog has to meet a susceptible dog during that time to continue transmission of the virus, otherwise it dies out), specific aspects of the virus in dogs (e.g. how long it is shed) or lack of recognition of disease in some areas (e.g. mild disease that doesn't get diagnosed) is unclear.

We've been looking for canine flu in Ontario for a few years now, with no "success" (that is, we haven't found it yet).

Are we flu-free at the moment? Probably not. I suspect it's lurking out there, but it's possible that it really hasn't made it to Ontario - yet.

If it's not here now, will it make it here eventually? Almost certainly. It's taking longer than I expected but all it takes is one infected dog entering the country. With the amount of cross-border dog movement, it's probably inevitable.

What about vaccination for canine flu? It comes down to risk of exposure and risk aversion. If flu is in the area, vaccination is a good idea. If flu is in adjacent areas, it's also a good idea. If flu isn't recognized in the area, it's a matter of how much risk people are willing to take and thinking about higher risk situations, as described below.

What about vaccination in Ontario, or other places where the virus doesn't seem to be present? It's hard to say when to recommend canine flu vaccination. Certainly, vaccination of dogs traveling to areas where canine flu is or has been present is a good idea. Vaccination of dogs that engage in high risk activities such as going to shows or kennels is also prudent, since these are the places where we may see the firsts outbreaks if/when canine flu makes it here. Vaccination of low-risk dogs in the province is probably not necessary at the moment (unless people are very risk averse and don't want to take any chances).

Why vaccinate?  It's just "the flu"... This is an attitude that the human public health field battles all the time. Most people who get human influenza (humans can't get the dog version of the virus) feel crappy for a few days and get over it. The perception that it's only and always a mild disease keeps some people from getting vaccinated. However, thousands of people die from flu complications, particularly the very young and elderly individuals. Vaccinating everyone helps reduce the chance that these high-risk people will get sick. Also, while rare, serious (including fatal) infections can occur in otherwise healthy people. In dogs, there's probably actually more indication to vaccinate if there is a realistic risk of exposure. Canine flu can cause classical flu-like disease, akin to the typical human case. However, severe (often fatal) pneumonia can also occur in otherwise healthy dogs. High rates of severe disease were reported initially when canine flu was first identified. It seems like severe disease rates have dropped, but it's still a concern. I wouldn't be surprised if severe disease is more common in dogs with canine flu than in people with human flu.

Whether or not to vaccinate is a discussion dog owners should have with their veterinarian, considering the risk of exposure, risk of severe illness and risk aversion. At the same time, people in areas where flu has not been identified need to be on the lookout for it, to ensure that it gets diagnosed promptly if it emerges, and that information gets communicated to veterinarians and the dog-owning public so that appropriate responses can be made.

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A case report highlighted by TheHorse.com and presented at the ASM/ESCMID MRSA conference in Washington DC last week described a horse-associated methicillin-resistant Staphylococcus aureus (MRSA) infection in Dutch girl.

The girl, a 16-year-old with a severe neuromuscular disease who was wheelchair-bound and on a ventilator, developed an infection following an insect bite. When the infection didn't respond to initial treatment, a sample was taken for culture and MRSA was identified. The girl didn't have any known risk factors for MRSA infection but had had close contact with a foal. The Friesian foal had been at a veterinary hospital prior to the girl's infection. It had a wound infection that was successfully treated with antibiotics, but no culture was taken at the time. The foal was considered a possible source of the MRSA, particularly since the strain that was recovered was ST398, which is widely found in livestock and which is regularly seen in horses in the Netherlands. After the girl's infection was identified, the foal was tested and was also found to be carrying MRSA. The girl's infection was successfully treated and the foal eliminated MRSA carriage without treatment (which is expected in horses because long-term carriage of MRSA seems to be rare to non-existent in this species).

The source of the infection could not be definitively proven, but given the fact that the horse was at a facility that regularly sees MRSA cases, that the strain involved is typically associated with livestock, and that the girl had no other livestock contact, it's a reasonable to assume it came from the foal.

We've known for a few years that MRSA is an issue in horses, and that it can be passed between horses and people - in both directions. Equine veterinarians and horse owners have abnormally high MRSA carriage rates. MRSA carriers are people who have MRSA living in or on them (most often in the nose) without any signs of infection. Most carriers never have a problem, but disease can develop in some situations. The incidence of human MRSA infections transmitted from horses is low, although it's almost certain that many horse-associated MRSA infections are not reported because the link with horses isn't made or people don't mention the horse contact. TheHorse.com article is incorrect in stating that this is only the third case of horse-to-human MRSA infection, since we've already published two such reports, one of which included multiple cases. Regardless, it's an uncommon problem but it is probably also under-recognized. Horse owners shouldn't panic about MRSA, but they should realize that MRSA is circulating in the horse population and that by nature of their frequent and close contact with horses, they are at higher risk for MRSA carriage, and likely also infection.

More information about MRSA in horses can be found on the Worms & Germs Resources - Horses page.

(click image for source)

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The British Small Animal Veterinary Association (BSAVA) has updated its practice guidelines for management of MRSA and MRSP.

Overall, there’s good information in the document with an emphasis on routine infection control as the key measure to reduce the impact of MRSP and MRSA. I’d like to see more emphasis on developing an overall infection control program, but the emphasis on basic principles such as hygiene is good.

Like any guideline document, there will be some disagreements in recommendations. I agree with the majority of what's written, although there are some recommendations that I wouldn’t make, and some additional areas that I’d address. That’s not surprising since most of the recommendations are based on opinion rather than evidence because we don’t have solid evidence for most areas, and there isn’t necessarily a single "right" answer to many questions at this point.

Typically, guidelines assess and report the level of evidence on which recommendations are based, but that’s not done here. Letting people know the evidence (or here, the relative lack of evidence) is a useful part of guidelines. How the recommendations are worded can also play a role. Here, they perhaps overstate the strength of evidence through use of wording such as saying something "will" have an impact, when we really should say it "might." In the absence of evidence, good common sense measures can be recommended and implemented, however we need to remember that we have major limitations in our knowledge. We need to figure out which infection control practices are effective.

I have a major problem with one recommendation: "Colonised animals should be treated with a chlorhexidine shampoo and intranasal fusidic acid or mupirocin once daily." There is simple no evidence supporting the use of active measures to eliminate MRSA and MRSP.

• For MRSA, there is reasonably good evidence that dogs and cats eliminate it on their own in a reasonably short period of time.
• For MRSP, we simply don’t know how long they can be carriers. I suspect that long-term carriage can happen in some animals, so decolonization might be attractive, but we don’t know what to do yet.
• There is absolutely no evidence that intranasal antibiotics are effective in dogs and cats. I have serious doubts that someone can adequately administer a topical antibiotic to the nasal passages of a dog, and particularly a cat.
• If this recommendation is adopted and widely used in the UK, I suspect the country will be an international leader in fusidic acid- and mupirocin-resistant bacteria.

Overall, there are some good recommendations in the guidelines, including the general infection control sections. We need to improve our baseline level of infection control and hygiene to reduce the impact of MRSA, MRSP and a variety of other concerning microorganisms. At the same time, we need to acknowledge our limited knowledge in a lot of areas and the fact that we are really working based on common sense and extrapolation from human medicine, with little direct evidence from veterinary medicine. Much more research is necessary, a major limitation of which is the limited priority given to companion animal infection control by research funding agencies.  This has to change to help control the impact of bugs like MRSA and MRSP on both animals and people.

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Rabies is pretty rare in horses, but there have been a few reports this summer.  Though rare, rabies is still a major concern because it's invariably fatal in horses, and almost always fatal in people.

Rabies was recently diagnosed in a horse in Eddy County, New Mexico. It started showing undefined signs of rabies and was euthanized two days later. Several people who worked with the horse are undergoing post-exposure treatment.

While rabies can potentially be spread from horses to people, I'm not aware of any confirmed cases of such transmission. Since rabies usually kills people, even a plausible risk is cause for concern. Additionally, and perhaps more importantly, rabid horses can be very dangerous, and multiple people have been killed by aggressive rabid horses. 

Rabies should be a core component of a horse's vaccination program in any part of the world where rabies is present in the wildlife population. Unfortunately, that's not always understood. One area resident stated she'd never heard of rabies in horses, and while she has her dogs and cats vaccinated, she hasn't vaccinated her livestock. No vaccine is 100% preventative, but rabies vaccination is a cheap and very effective way to reduce the risk of this fatal disease significantly.

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The mosquito-borne diseases eastern equine encephalitis (EEE) and West Nile (WNV) continue to rear their ugly heads in the northeast as we get further into the late summer season during which they are most common.

On August 13 there was an unconfirmed report of a case of West Nile in a horse at Woodbine Racetrack, just north of Toronto.  No additional details have been forthcoming regarding the severity of the infection or the status of the horse, if WNV infection has in fact been diagnosed.  Nonetheless, the Ontario HBPA is urging horse owners to ensure the vaccination status of their animals for West Nile is up-to-date.  Unfortunately, if horses are not already vaccinated at this point, even vaccinating them immediately may still leave them susceptible to virus for the next few weeks until they are able to fully respond to the vaccine.  This news follows close on the heels of news reports regarding increased numbers of WNV-positive mosquito pools in various regions north of Toronto, and thus is not altogether surprising.

The first case of West Nile in a human in New Jersey was recently diagnosed in a man from Mercer County.  Again, no additional details about the severity of the infection or the man's condition are available, but the public is once again being urged to protect themselves against mosquitoes by wearing long sleeves and pants, using insect repellant, and eliminating standing water in which mosquitoes may breed on their property.  Elsewhere the death on August 14 of a four-year-old girl in New York from infection with EEE has been reported.  She is the fifth person in New York state to die from the disease in 40 years.  The girl first began showing signs of infection earlier this month, but the diagnosis of EEE infection was only reached last week.  EEE has a high mortality rate in humans as well as horses.  Just as infection in animals can act as sentinel indicators for disease risk in humans, these human cases indicate that WNV and EEE are active in these respective areas, and humans and horses alike are at risk of infection.  Mosquito avoidance can help protect both, and in addition timely vaccination of horses can help decrease the risk of disease.

This Worms & Germs blog entry was originally posted on equIDblog on 17-Aug-11.

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China has a huge canine rabies problem, with thousands of human rabies deaths each year. There are several reasons for this, including large feral dog populations, inadequate vaccination of pet dogs, differences in approach and access to veterinary care for pets, inadequate education regarding dog bite prevention, and presumably inadequate education of people and/or healthcare personnel regarding when and how to seek proper post-exposure treatment.

Periodically, the knee-jerk reaction of dog culling rears its head in China, despite the ineffectiveness of culling alone as a rabies control tool.

Recently, authorities in Guangdong province have banned ownership of dogs (in most situations) and given residents until August 26 to get rid of their pets. Dogs remaining at that time will be put down, except for dogs that are used to protect property worth ~ $750 000 (or more). Those dogs must be vaccinated and "kept locked up." (Why the same things (i.e. vaccination and confinement) can't be done with any other pet dog is unclear, since being owned by a rich person doesn't make a dog less susceptible to rabies.)

An expert from the Chinese Center for Disease Control summed up the issue nicely: "This [ban] is not scientific, not humane, and it will not last long. In short term, maybe it could be effective, but after that, people still want to keep dogs."

Culls don't work well. A cull can decrease the population of concern for a time, but it's extremely unlikely that it would reduce the population enough to have any longterm effect. Dogs can reproduce quickly and replace the culled animals in a short period of time.

What would make more sense?

• Widespread vaccination of pet dogs, to reduce the risk of exposure of people from pets that get infected from feral dogs.
• Widespread vaccination of feral dogs, to reduce exposure of people and pet dogs. Achieving high vaccination rates (>70%) in the feral population is a critical control measure, but can be very challenging.
• Education of people about dog bite prevention.
• Education of people about dog bite care, particularly ensuring that they seek post-exposure treatment if bitten by a feral dog or a dog of unknown rabies status that can't be quarantined for 10 days to ensure it's not rabid.
• Education of healthcare personnel so that everyone who needs post-exposure treatment gets it (and gets it done right).
• Education of public health personnel to ensure that the two points above get done right.
• Ensuring adequate supply of good quality rabies vaccine and antibody for post-exposure treatment.

Yes, these measures require more work than a cull, and to some degree they also require a culture shift in the approach to keeping pets, but if China really wants to start preventing the thousands of rabies deaths that occur annually, that's what needs to be done.

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Adding a new twist to the already very concerning situation in Australia, Hendra virus infection has now also been identified in a dog. It's been a bad year for Hendra virus in Australia, with larger numbers of cases of this highly fatal disease in horses in a geographic range that seems to be expanding. Spread by flying foxes (fruit bats), Hendra virus predominantly infects horses, but can be transmitted to people working with infectedhorses.

The Australian Animal Health Laboratory in Geelong has now announced diagnosis of Hendra virus infection in a dog. The dog is from a quarantined farm in Queensland where the virus has been identified in a horse. The dog was healthy and was tested as part of a standard policy to test dogs and cats on infected farms. It's great to see this approach being used, since it helps identify other potential sources proactively - something that is often overlooked in outbreak investigations that focus only on the main species that are already known to be involved.

In this case, the dog had antibodies against the virus in its blood. That means that it was exposed to the virus and mounted an immune response. It doesn't indicate whether it was exposed recently or in the past. Two tests for the virus itself were negative, suggesting that the dog's immune system eliminated the virus (or that the virus isn't really capable of surviving for long in a dog). This is a good news/bad news scenario.

Bad news:

• Dogs can be infected. It increases the range of known susceptible species.
• If dogs can be infected and shed live virus, then they could be a source of infection for other individuals, including people.
• The dog wasn't sick. This might sound like strange "bad news," but healthy carriers of infectious diseases are harder to spot and control than ones that are sick.

Good news:

• The dog wasn't shedding the virus. That's critical since if dogs can be infected but not infectious (i.e. if they can carry the virus but not transmit it), then they are of limited concern.
• They have been testing farm dogs and cats as a routine measure, and this was the first positive. Infection of pets therefore must be relatively uncommon even on farms where the virus is active.
• The dog wasn't sick. While it's only one case and doesn't guarantee dogs won't be affected clinically, this might suggest that dogs just occasionally get exposed with no disease. Since it's highly fatal in other species, that's a good thing.

What should be done based on this?

• Probably not much more than should have been done before this finding, but it's a good reminder about the potential involvement of other species.
• Dogs and cats should be kept away from fruit bat roosting sites.
• Dogs and cats should be kept away from infected horses.
• If a farm is quarantined because of Hendra virus, dogs and cats should be tested and quarantined. Quarantining the animal while testing is underway helps reduce the risk of an infectious dog or cat (should that occur) transmiting the virus to people on the farm, or wandering away and exposing other people or animals.
• Animals of any type in areas where Hendra virus is active that get sick with signs that could possibly be consistent with Hendra virus infection should be tested.

This should also be taken as yet another reminder that infectious diseases are unpredictable. Considering the potential involvement of different species in a proactive manner as was done here is critical.

Image: Bay Horse and White Dog by George Stubbs (1724-1806)

This Worms & Germs blog entry was originally posted on equIDblog on 26-Jul-11.

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As Australia faces a particularly bad year for Hendra virus, with possible expansion of the range of this serious disease, there have been calls for a mass cull of flying foxes (fruit bats).  These bats are the reservoir of the virus but also a protected species. The virus lives in the bats and is spread mainly through their urine. Horses that are exposed to bat urine or feces (e.g. grazing under a tree where bats are roosting) can become infected and then serve as a source of human infection. Being a highly fatal disease for which there is no available vaccine, looking at ways to reduce exposure to the virus is critical.  When you have a wildlife-associated disease, questions about trying to eliminate the wildlife source often arise.  Any discussion of culling wildlife leads to intense debate, and this situation is no different. Some people support culling bats in areas around people and horses, while others are opposed on various grounds, including a lack of evidence that it will be effective.

Can fruit bat numbers really be decreased? A lot of bats would have to be killed to have a significant impact on the population. Bats can reproduce quickly and migrate readily, therefore a single cull may have only a limited and short-term effect. A good understanding of the dynamics of the bat population is required to determine how many would need to be killed in a given area to have any significant impact. As Biosecurity Queensland's chief veterinarian RIck Symons stated "Culling is against government policy. I believe in terms of biosecurity it's counterproductive, because it does stress flying foxes and they're more likely to excrete (the virus). It could be filled by another bat colony the next day and if you're moving them on, you're moving it on to somebody else and it's somebody else's problem, so that is not the solution."

Will a cull actually achieve anything? Even if effective at reducing bat numbers (probably just in the short term), culls don't necessarily have an impact on disease rates. All bats would not be eliminated, and it's unclear whether there is a critical mass of bats that is required to transmit infection or whether a small number of bats distributed across the same region would be as likely to result in infections. Small or temporary decreases in bat numbers may have no effect.

What unintended consequences might occur if a cull is effective at reducing bat numbers? Removing an animal from any ecosystem has an effect, and it's important to be confident that that effect isn't accompanied by problems of its own. I don't know enough about fruit bat ecology to say much here, but if this species is greatly reduced, are there other species that will come and occupy that ecological niche, and might they be associated with problems of their own? Careful scientific study can help to figure this out in theory, but you can never be certain.

Are other control measures, such as removing roosting sites from pastures and other bat avoidance measures, being adequately used? Culls should only be considered when other measures have failed, but it can be difficult to ensure or enforce compliance with these other measures. Certainly, people in endemic areas should remove trees in which bats roost from pastures. However, not all Hendra cases are associated with identifiable roosting sites.  For example, one affected Queensland farm does not have any fruit bats residing on the property, but it lies along a common flight path for the bats.

It's easy to talk about avoiding a cull when you're not in the heart of the Hendra epidemic, and I understand the reasoning behind the calls for a cull. Hendra is a devastating disease that's a threat to both horse and human health, and it's unpredictable - and that's scarey for a lot of folks. People that have been exposed face an incredibly stressful period while they wait and see if they've been infected with a virus that kills in ~50% of cases. A vaccine is probably still a couple of years away, leaving a period of continued risk and stress. With such a serious disease, considering culling is reasonable. However, it can't be a knee-jerk reaction to public outcry. It needs to be based on sound science to ensure that if it's used, it will be effective. The impact on this protected species also can't be ignored.

This Worms & Germs blog entry was originally posted on equIDblog on 19-Jul-11.

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When it comes to public health concerns about staphylococcal bacteria from pets, most of the attention gets paid to methicillin-resistant strains like MRSA. That's not surprising considering how important MRSA is in human medicine. However, staph that aren't methicillin-resistant can also be a problem, since they can cause the same types of infections that resistant types can (they are just easier to treat). Another issue that often gets overlooked is staphylococcal food poisoning.

Staphylococcal food poisoning is one of the most common foodborne illnesses and results from growth of certain strains of staphylococci in poorly handled or stored foods. If staph get into food and the food is kept at improper temperatures, the bacteria can grow. If the strain of staph that's in the food is one that can produce enterotoxins, these toxins can accumulate in the food at high enough levels to cause food poisoning when eaten. In most cases, people are probably the origin of enterotoxin-producing staph that contaminate food, but pets are another possible source.

A recent study in Vector-borne and Zoonotic Diseases (Abdel-moein et al 2011) looked at enterotoxigenic staph in 70 dogs and 47 cats. Swabs were collected from the mouth, nose and wounds. Nasal swabs were also collected from 26 people. The researchers isolated enterotoxigenic Staphylococcus aureus (strains of S. aureus that possessed genes for enterotoxin production) from 10% of dogs and 2.1% of cats, as well as 7.7% of people. Most of the positive samples from pets were oral samples.

This study shows that dogs and cats can be potential sources of strains of S. aureus that cause food poisoning. Since the staph are often in the animals' mouths (and therefore presumably shed in saliva), animals can potentially contaminate food with these enterotoxigenic staph fairly easily, but it's unknown how often this occurs.

Prevention measures are pretty basic but should be considered, including:

• Keeping pets off kitchen counters.
• Discarding foods that pets have licked.
• Washing hands after pet contact, before handling food.
• Properly storing food, so that even if it gets contaminated with staph, the bacteria don't get the opportunity to grow and produce toxins.
• Photo from http://www.wagreflex.com/2009/06/taking-cat-ownership-to-the-next-level.html

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The more we look, the more we find when it comes to MRSA (methicillin-resistant Staphylococcus aureus). As people start looking for it in different animal species, it's often found. We've found it in many species already, including dogs, cats, rabbits, pigs, walruses, dolphins and alpacas, so it's not a big surprise to see a recent paper in the Journal of Clinical Microbiology (Ferreira et al 2011) about suspected MRSA transmission between a human and a hamster.

The case report describes a person with advanced cystic fibrosis who had undergone a lung transplant and had various other medical problems. Prior to another surgical procedure, MRSA was identified through routine pre-operative screening. Nasal and rectal swabs were then collected from the person's three pet hamsters, one of which was positive. The MRSA isolates from the human and hamster were the same, supporting transmission from one to the other. Given the person's underlying health problems, frequent contact with the healthcare system, the typical human origin of the strain that was found, and limited contact of hamsters with other animals or people, it is most likely that MRSA was transmitted from human to hamster in this case.

The paper concludes with: "Should testing of the pets of MRSA-positive patients be recommended? At this point, we recommend that MRSA-positive patients be informed that their companion animals can be potential sources of infection or reinfection. In the presence of a MRSA-positive human or animal, heightened hygiene practices should be instituted and unnecessary close contact should be avoided. Screening of household pets might be indicated in situations of recurrent MRSA infections despite adequate treatment or when immunocompromised patients live in the household."

That's consistent with our standard recommendations and hits most of the key points:

• Awareness is critical. People need to know what the risks might be and what they can do about them so that they can make informed decisions and realize why recommendations are being made.
• Testing of pets is rarely useful, particularly in the absence of a recurrent MRSA problem.
• Good hygiene practices are critical.

I don't really agree with the comment that testing of pets might be indicated when immunocompromised people are in the household (although the comment is properly hedged by saying "might be indicated"). A large percentage of the population has some degree of immunocompromise, and there's a huge spectrum from minimal risk to tremendous risk. Even in high-risk patients, screening is questionably useful to me because it doesn't really change what I'd do.

• If I screened a hamster from a high-risk person and found MRSA, I'd say that it probably came from the person, that it's possible it could be transmitted back to the person, that good hygiene practices should be followed and close contact should be restricted. There's no indication (or ability, in reality) to treat the hamster.
• If the hamster was negative, I'd say it was possibly negative because screening is not 100%, that the hamster could be exposed to MRSA from the owner at any time, and so to manage unknown colonization and reduce human-hamster transmission, I'd recommend good hygiene practices and restriction of close contact.
• If I'm going to do the same thing with a positive and negative result, I don't do a test.

This paper should be yet another reminder that we live in a complex relationship with our pets, including microbiologically. While we need to consider the role of pets in human infection (and the role of humans in pet infection), and we need to balance that with the positive aspects of pet ownership in order to maximize the benefits while minimizing the costs.

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An interesting study published recently in Veterinary Dermatology (Bartlett et al 2011) looked at bacterial contamination of ear cleaning solutions used on dogs at home. Ear cleaners are widely used by dog owners, but since the bottles the cleaners come in are used repeatedly and can have direct contact with the ear, there’s a chance for contamination of the bottle and/or its contents.

In this study, the researchers collected ear cleaner bottles from dog owners and cultured both the applicator tips and the contents. Bacterial contamination was detected on 10% of the bottle tips and in 2% of the solutions. The relative numbers make sense, since the tips are most likely to have contact with the ear. Regardless, this shows that a small but still reasonable percentage of bottles contain bacteria that could be inoculated into the ear.

Finding bugs is one thing, but determining if they are types that can cause disease is another. The researchers identified a few different bacteria, including Staphylococcus pseudintermedius, which is an important cause of ear infections. This isn't too surprising since the bugs that cause infection are typically those that are also normally found in (healthy) ears at low levels (and therefore the types of bugs with which cleaner bottles might have contact).

Expired ear cleaners were more often contaminated. This doesn’t necessarily mean that age leads to increased risk of contamination. It could just indicate that bottles that have been used more and over longer periods of time are more likely to become contaminated. Similarly, large bottles more often had contaminated tips, probably because of more overall use (and correspondingly more chance for contamination).

An interesting aspect was the finding that solutions containing Tris-EDTA had higher contamination rates. Tris-EDTA is a solution that is often included in ear cleaners as it has been shown to be useful for treatment of infections caused by Gram-negative bacteria.

What does this mean for people that clean their dogs’ ears? It’s hard to say. We don’t know whether a little bit of bacterial contamination poses a realistic risk. However, it’s reasonable to consider using smaller bottles and discarding them after they are used to treat a dog with an ear infection (as opposed to regular ear cleaning).

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In trying to keep up with technology, my lab has started adding a QR code to posters presented at research meetings. The code links to a page on the Worms & Germs Blog Resources page that houses a collection of research posters that people can view and download. You can also go directly to the poster site by clicking Research Posters on the "Topics" bar on the left side of the Worms & Germs Blog homepage, or through the Resources tab at the top of the homepage. Check back regularly to see new additions to the list.

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A California teen has been battling a chronic and severe infection acquired from a fish tank. Five years ago, Hannele Cox cut her hand when she pulled it out of an aquarium. It sounds like it was a pretty minor scratch, but it doesn't take much to cause an infection under the right circumstances.

A while after the injury, infection was apparent. A round of antibiotics didn't fix it (no word on whether any bacterial cultures were performed at that point). Eventually, a dermatologist diagnosed the problem: Mycobacterium marinum infection. One problem with infections like this is that they are sometimes not diagnosed until they are quite advanced. If the patient doesn't mention the aquarium exposure and/or the physician doesn't ask about pets, an infection like M. marinum might not be considered.

Mycobacterium marinum infection is sometimes called "fish tank granuloma" in testament to its common association with fish tanks. It can be found in both freshwater and marine fish (and the water in their tanks), and most often infected fish don't have any signs of disease. Therefore, you have to assume that any fish and any aquarium could be infected, and therefore a potential source of human infection.

Infections with M. marinum usually develop a couple of weeks after exposure and are characterized by small bumps (papules) on the skin that progress to shallow ulcers. Typically, infection is not very invasive and responds to treatment, although months of treatment may be required. Sometimes, the infection can spread to deeper tissues, making it much harder to treat. Unfortunately, that's what happened to Hannele Cox. Her infection has not responded well to treatment and has spread to deeper tissues, including bone. She's had two surgeries to try to save her hand, and at least one more is planned. Amputation isn't outside of the realm of possibility, but will hopefully be avoided.

Fish owners should be aware of the risk of M. marinum infection.  While fish are often ignored as a potential causes of infection and the overall risk is low, there are simple measures that can be undertaken to reduce the risk of acquiring an infection from fish tanks. These mainly involve limiting contact with fish tank water and the use of good general hygiene practices:

• Contact with aquarium water should be minimized
• Never dump aquarium water into kitchen or bathroom sinks.
• Promptly clean up any aquarium water spills.
• Take care when putting your hands in the aquarium, especially if there are sharp surfaces (e.g. rock, coral) that might result in cuts or abrasions.
• Hands should be washed thoroughly after contact with aquarium water.
• People with compromised immune systems should not have contact with aquarium water. They should have someone else clean their fish tank.

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As many of you know, there was a large ringworm "outbreak" at the Newmarket (Ontario) OSPCA shelter in 2010 that led to a public outcry in response to plans to depopulate the shelter. In the aftermath of the event, an independent investigation was launched, headed by Mr. Patrick LeSage (former Chief Justice of the Ontario Superior Court) and Dr. Alan Meek (former Dean of the Ontario Veterinary College). The investigation involved a comprehensive examination of activities pertaining to the outbreak and shelter operations, in conjunction with relevant experts (disclosure: I was one of those).

The report of the investigation is now available, and covers important aspects such as whether an outbreak was actually present (short answer: no) and whether there were major problems in shelter operation (short answer: yes). Most importantly, it provides a comprehensive set of recommendations to improve the operations of the Newmarket shelter and OSPCA as a whole.

The report, in its entirety, was released today by the OSPCA and is available for download on their website. The report is on the site in multiple files: the main report is listed as "Index" and contains the ~90 page overview and recommendations. The expert reports, which might also be of interest, are tables D1-3, E, F and G.

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A few more details are available about the apparent case of a person surviving rabies infection that I also wrote about in a post a few days ago. The affected individual is an eight-year-old girl from Willow Creek, California. She initially had non-specific signs of illness (which is not unusual for rabies) and at her first visit to a doctor, it was thought that she probably had the flu. However, her illness progressed quickly and she developed severe neurological signs shortly thereafter. She was sent to the University of California Davis Medical Center, where she was diagnosed with rabies a week later. I'm not sure if they suspected rabies before the diagnosis and started treatment, or whether they didn't initiate treatment until after the diagnosis was made. Presumably, they started treated based on a suspicion of rabies because she would have deteriorated greatly during that week otherwise.

Her current health status isn't reported so it's not clear whether she is truly out of the woods or whether there are any residual neurological abnormalities. If treatment is successful, this girl would be only the fifth person (as far as my count goes) known to have survived rabies infection. Presumably she was treated with a form of the Milwaukee protocol, which involves putting the patient in a medically-induced coma and administering a series of anti-rabies drugs. When it was first reported to be successful, this protocol was hailed as a remarkable breakthrough in the management of rabies (which is was).  However, it still has a low success rate, which is a testament to the severity of rabies and the often late recognition and initiation of treatment. Hopefully more details about the treatment protocol and her clinical status will be made available soon.

On a happy related note, Jeanna Giese, the girl who in 2004 became the first known rabies survivor in the world, graduated from College a few weeks ago at the age of 21.

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Although limited on information, there's a recent report of a person with rabies in California, with some hope for survival. Rabies was apparently diagnosed in the person on May 6. Incredibly, not only is the woman alive, but she is reported to be in "stable condition" and improving at UC Davis Medical Center. That's remarkable because rabies is almost always fatal, and death usually occurs fairly quickly by the time rabies is suspected and diagnosed. Rabies survival has been reported but is extremely rare.

While it's far too early to talk about survival and cure of the woman's illness, there are many different factors that could be involved in this potentially successful treatment.  These include very rapid administration of anti-rabies treatment, use of the "Milwaukee protocol" (which was the first successful treatment protocol for rabies in a person, which has also failed to be successful numerous times since), pre-existing partial immunity from previous vaccination, and/or the whims of biology and the immune system. Hopefully, this person will continue to improve and more information will be made available about why treatment has been successful so far.

The source of rabies is suspected to have been feral cats, although this is far from certain and it may be that this presumption is based on the lack of other more likely possibilities. While this is an encouraging report, it doesn't change the fact that rabies almost always kills, and it's almost 100% preventable with proper post-exposure treatment. People need to be aware of how to avoid rabies and that prompt treatment is needed anytime rabies might have been encountered.

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Today (like most days) I answered questions about the potential for transmission of methicillin-resistant Staphylococcus pseudintermedius (MRSP) between people and pets. We have a long way to go before we fully understand the issues, but research continues to progress and we're learning more and more. A recent study by Dr. Engeline van Duijkeren and colleagues from Utrecht University published in Veterinary Microbiology (van Duijkeren et al. 2011) steps up our knowledge another notch.

In their study, the authors enrolled 20 households that owned pets with MRSP infections. They went into the households and collected samples from the index pet (the one with the MRSP infection), other pets, people and the household environment.  At the time of sampling, 10 of the infected pets had gotten over their illness while the other 10 still had active infections.

Some highlights of the study:

• 4/14 (36%) of other dogs and 4/13 (31%) other cats in the households were MRSP carriers. In households where the pet still had an active infection, an astounding 86% of the other animals were carriers. All these numbers are much higher than the expected baseline rate of MRSP carriage by healthy pets in households, giving strong support to the notion that MRSP is being passed between pets in households with an infected pet.  From an infection control standpoint, it's probably reasonable to assume that a pet living with an infected animal is a carrier.
• MRSP was isolated from 2/45 (4%) of nasal swabs from people. This is not too surprising, since we know that MRSP (and its susceptible counterpart, methicillin-susceptible S. pseudintermedius (MSSP)) can be transmitted between people and pets. This study shows us, however, that even when there is apparent MRSP transmission going on between pets in the household, it doesn't seem to commonly involve people.
• MRSP was found in the environment in 70% of houses (and 90% of household where the pet was still infected). These are pretty big numbers but are not really unexpected, since if MRSP is in and/or on animals, it's bound to be found in the environment. Whether the environment is a potential source of human or animal infection isn't known, but it's something to consider.

This research gives more evidence that MRSP can be spread readily between animals but less so between animals and people. It could be because animals have closer contact with each other in a household than with people, but a bigger factor is probably that S. pseudintermedius is more adapted to living on animals than on people.

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An important concept when dealing with infectious diseases is consideration of the risk that an animal has been, or will be, exposed to a particular microorganism. Some diseases vary greatly geographically, and something that's very important in one region may be rare or non-existent in another. Good veterinarians are aware of disease trends in their area and make informed decisions about vaccination and anti-parasitic treatments based on what's happening in the area. They also know which diseases are common and which are rare or non-existent.

But that only works if the pets stay in their "home" area. Traveling with pets can result in exposure to various infectious diseases they wouldn't normally encounter. If a veterinarian doesn't know a pet travels, they can't make proper recommendations for preventive medicine.

Additionally, travel history can be very important when evaluating a sick animal, since there may be diseases that need to be considered in a traveling pet that wouldn't be an issue with a local pet. However, it's easy to overlook or forget about travel history. Pet owners need to tell their veterinarians about "recent" travel with their pets. What does recent mean? It's hard to say. For some diseases, exposure within the past few days is all that's important. For others, it may be weeks or months. So, if you have a sick pet and have traveled any time in the past year with it, it's good to mention that to your veterinarian. It may have nothing to do with the current illness, but it never hurts to let them know anyway. In some situations, it may be the critical piece of information needed to trigger thinking about a specific disease.

Some examples of diseases that may be travel-related (at least to dogs in most parts of Ontario):

• Blastomycosis, a fungal disease, tends to occur predominantly in specific areas. It's not too common elsewhere, but travel to high-risk areas puts blasto on the list of possibilities in certain cases.
• Around here, there's no indication for heartworm preventive treatment during cold winter months, but that changes if the pet goes to areas where mosquitoes hang around all year.
• Some tickborne diseases have very specific ranges that correspond to their primary hosts and certain vector species (such as birds). In Ontario, ticks are currently quite geographically focused and many dogs have little risk of exposure. Travel to one of the tick hotbed areas changes that, and means that certain tickborne diseases need to be considered.
• Canine influenza currently seems like a non-entity in Ontario. We're still looking for it but haven't found it. It is present in some places in the US, and at times, is a big problem. Travel to a place experiencing a canine flu outbreak would be a good indication to consider canine flu vaccination.

What to do?

• If you travel with your pet, part of your pre-travel checklist should be an appointment with your veterinarian to go over anything that needs to be done, be it vaccination, deworming, flea control, heartworm preventive or anything else. (It's also a good time to make sure there's nothing else going on with your pet, because you don't want a pet health crisis en route.)
• If your pet gets sick and has traveled, make sure your veterinarian knows where you went and when.
• If you travel regularly, even if it's not long distances, it's good to discuss it with your veterinarian to see if anything is required for your pet. Even if you just go a couple of hours away to a cottage regularly during the summer, you may be exposing your pet to something different.

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I received this question yesterday, pertaining to a potential therapy dog.

Valley Fever, also known as coccidioidomycosis, is a fungal infection caused by Coccidioides immitis or Coccidioides posadasi. These fungi live in the soil and are most common in the southwestern US, northern Mexico, and parts of Central and South America. They are part of an unusual group of fungi called "dimorphic fungi," meaning they exist in two forms. One form in found in the environment (soil). This arthroconidial form is the infectious form. The other yeast-like form is present in the body tissues during infection, but is not (or at least is very minimally) transmissible.

Disease from Valley Fever is rare in healthy people.  These fungi are mainly a concern in people with compromised immune systems. When illness occurs, flu-like disease, respiratory disease, rash and joint pain are the most common signs, but disseminated infection (i.e. infection throughout the body) is a much more serious form of the disease that can occur.

Valley Fever is similar in dogs, with most dogs have mild to inapparent disease, and most sick dogs having vague signs and respiratory disease. Cats often develop skin lesion. Disseminated disease can also occur.

While coccidioidomycosis can occur in both humans and animals, the risk of transmission between humans and animals is extremely low. The fact that it occurs in both humans and animals is because both humans and animals get exposed to the same sources, not because they spread it between each other.

However, there is a slight risk that shouldn't be ignored. There are two situations that are of concern.

• Bites: There is one report of a bite-associated infection in a veterinary technician. The risk of infection after a bite from an infected animal isn't known, but anyone bitten by an infected animal should seek medical advice. Presumably, nothing would be done initially but there could be close monitoring for disease so that it can be treated early if problems develop.
• Veterinary procedures: Infection has been reported in a person performing a necropsy (autopsy) on an infected horse. It was thought that infectious endospores were aerosolized when an infected area was cut with a saw as part of the procedure, and inhalation of the fungus lead to disease.

There's also a theoretical concern with handling bandage material from infected animals. While the active infection would be caused by the minimally infectious tissue form of the fungus, it's possible that infectious arthroconidia could develop in a bandage.

People with infected pets have little about which to be concerned. The main risk (which is also very low) is infection from a bite from an animal with disseminated disease. Basic bite avoidance should minimize this risk, however medical care should be sought following any bite and people at high risk of serious infection (e.g. people with compromised immune systems) should take particular care when interacting with infected animals. If a pet owner has to change a bandage on an infected animal, they should wear gloves, double bag and immediately dispose of the bandage, avoid contamination of the environment during bandage changing and thoroughly wash their hands after completing the task.

Image: The infectious arthroconidia of Coccidioides immitis (source: CDC Public Health Image Library #476).

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Plague has been identified in a dog and cat from New Mexico. It’s not surprising, since plague is present in some wild animal populations in that region, but it’s still noteworthy because of the serious nature of the disease and the potential for transmission to humans.

Plague is a bacterial infection caused by Yersinia pestis. It’s carried mostly be certain types of rodents in different regions of the world, including parts of the southwestern US. It’s usually spread by fleas that bite an infected rodent and then bite a person or other animal, but it can also be spread by close contact with an infected animal. Cases in cats and dogs are uncommon, but occur in areas where plague is present in rodents, when pets have contact with infected fleas or close encounters with infected rodents (or rodent carcasses).

The latest two cases were in Santa Fe and Rio Arriba Counties in New Mexico. No details were provided about the form of plague (e.g. bubonic, pneumonic), the suspected source of infection or whether there is concern about human exposure. Finding plague in a pet is a concern for a few reasons. It indicates that plague is present in wildlife in the area, and people could be exposed from the same sources as the pets (i.e. fleas, contact with live or dead wildlife). Also, transmission of plague from pets to their caretakers can occur, particularly from cats with pneumonic plague (respiratory tract infection). Knowing that a person has had contact with a pet with plague is critical to making a prompt diagnosis. According to the World Health Organization, plague continues to infect more than 2000 people every year.

The New Mexico Department of Health has made the following recommendations:

• Avoid sick or dead rodents and rabbits, and their nests and burrows.
• Keep your pets from roaming and hunting and talk to your veterinarian about using an appropriate flea control product.
• Clean up areas near the house where rodents could live, such as woodpiles, brush piles, junk and abandoned vehicles.
• Sick pets should be examined promptly by a veterinarian.
• See your doctor about any unexplained illness involving a sudden and severe fever.
• Put hay, wood, and compost piles as far as possible from your home.
• Don’t leave your pet’s food and water where mice can get to it.
• Veterinarians and their staff are at higher risk and should take precautions when seeing suspect animal plague cases.

 Photo: The vector of Yersina pestis: a flea (click image for source)

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There are a number of published studies regarding methicillin-resistant Staphylococcus aureus (MRSA) carriage by veterinarians, most reporting high rates compared to the general population. This is a concern because MRSA is an important cause of disease in both people and animals. Just having MRSA living in your nose doesn't mean you're going to get sick. Indeed, around 2-3% of normal, healthy people are likely carrying MRSA at this moment. However, if you are carrying MRSA, you are at increased risk of developing an infection under certain circumstances. In veterinarians MRSA carriage is also a concern because of the potential for transmission to patients (and potentially from those patients back to people).

A recent Australian study in the Australian Veterinary Journal (Jordan et al 2011) looked at MRSA carriage in different types of veterinarians. The rates were:

• 0.9% in industry and government veterinarians (who have limited contact with animals)
• 4.9% in small animals veterinarians
• 11.8% in veterinarians with horses as a major component of their caseload
• 21.5% in equine veterinarians

These results are similar to some of our earlier studies, with carriage rates in small animal veterinarians being  higher than would be expected for the general population, and carriage rates in equine veterinarians being very high.

Why do veterinarians have high rates of MRSA carriage?

There's no definitive answer but there are some likely causes. Veterinarians have contact with large numbers of pets and horses, and we know these animals can carry MRSA. Even if the percentage of dogs, cats or horses carrying MRSA is very low, when you multiply that by the number of animals a veterinarian touches every week, you can see how contact with an MRSA-carrier is pretty likely. Veterinarians also tend to have close contact with sites where MRSA can be found, such as the nose. This makes the chance of having contact with the bacterium itself more likely. An additional issue the often sub-optimal use of routine infection control and hygiene practices (especially hand hygiene), which may also increase the risk of MRSA transmission. Put all these together, and it makes sense that veterinary personnel are at increased risk.

Why do carriage rates tend to be higher in equine veterinarians?

It could be because MRSA is more common in horses than small companion animals. Another plausible explanation is the fact that the horse's nose (the most likely site for MRSA to be living) is commonly touched during examination and restraint, and horses have pretty big noses to start. Additionally, good hygiene can take more effort on some farms, as sinks and often even hand sanitizer are not as readily available as they are in a clinic.

More information about MRSA in companion animals can be found on the Worms & Germs Resources page.  More information about MRSA in horses can be found on our sister site, on the equIDblog Resources page.

(click image for source)

This Worms & Germs blog entry was originally posted on equIDblog on 19-Apr-11.

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The latest edition of CDC's Morbidity and Mortality Weekly Reports describes a case of rabies in a Michigan man from 2009. While human rabies in most developed countries is very rare, this is yet another reminder of the ever-present risk of rabies exposure in many regions, and the ongoing need to be proactive to avoid this almost invariably fatal - but almost completely preventable - disease.

In the 2009 Michigan case, the man woke one day with a bat on his arm. Bats are classic rabies vectors, and you have to assume that any bat has rabies until proven otherwise. If you can't be sure that you weren't bitten or scratched (something that may be easier said than done, because bats bites can be very tiny), then you have to consider yourself exposed if you've had contact with a bat and the bat wasn't tested and rabies-negative.

Unfortunately, the Michigan man did not seek medical attention, and nine months later he started to develop signs of rabies. It started off with pain and progressive numbness in his left hand and arm, and pain in his neck and back. He developed weakness in his left hand and soon could not grip anything or raise it more than a few inches.

While he was being evaluated in hospital, he developed breathing difficulties and had to be placed on a ventilator. Various diseases were considered and numerous tests were run. After a little initial improvement, he began to deteriorate, with more profound neurological signs.

Five days after he was admitted to hospital, his wife was asked about possible animal bites, but she didn't know of any. A couple of days later, a relative recounted being told about the bat encounter, but there was little that could be done at that point, and the man died three days later. Rabies was eventually diagnosed.

Because of the potential risk of exposure, 11 family members that may have had contact with the man's saliva received post-exposure treatment.

Sadly, you can almost guarantee that rabies could have been prevented if he had reported the bite and received post-exposure treatment (even months later). Rabies education is critical so that people know the risks of exposure and know to get medical advice after any encounter with a wild animal.

(click image for source)

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The US CDC is investigating a large, long-lasting and widely dispersed outbreak of salmonellosis that has been linked to contact with pet frogs, such as African dwarf frogs (see image). Between April 1, 2009 and April 5, 2011, 217 infections were identified in people in 41 states. A strain of Salmonella Typhimurium has been implicated.

Of the 217 infected people, 34% were hospitalized, which is quite a large proportion, but is probably due (at least in part) to the fact that stool samples aren't often cultured from people with milder disease (who don't go to the hospital). If you have severe diarrhea and are in hospital, you're more likely to be tested. As with most outbreaks, the 217 diagnosed cases presumably represent only the tip of the iceberg.

Of the people who got sick, 64% reported contact with frogs in the week before their illness began. Of these, 84% had contact with African dwarf frogs. This type of widespread outbreak with a single strain and a fairly clear link to a specific type of animal raises questions about whether there's a major breeder or supplier that is the source of the problem. Not surprisingly, the investigation identified a single water frog breeder in California as the source of frogs associated with this outbreak. Salmonella was identified from environmental samples at the breeder's facility. Testing is still apparently underway to confirm whether it's the outbreak strain, but it's pretty likely.

As with any other reptiles or amphibians, there are standard recommendations to avoid infections from aquatic (water) frogs:

• They should not be in households with high-risk people: children less than five years of age, the elderly, pregnant women and immunocompromised individuals.
• Care should be taken to prevent contamination of the house from aquarium/terrarium water.
• To avoid contamination, aquarium water should not be dumped down kitchen or bathroom sinks.
• Hands should be washed thoroughly after contact with aquarium water or the frogs themselves.

Photo: An African dwarf frog (Hymenochirus boettgeri) (photo credit: James Gathany).

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Heartworm is a parasitic infection (primarily of dogs) caused by Dirofilaria immitis, which is spread by mosquitoes.  In areas where the parasite is present, the standard recommendation is for preventive treatment of dogs during the mosquito season, and annual testing to make sure they don't have the disease. Numerous types of heartworm medication are available, and there's been considerable debate about the potential for emergence of heartworm resistance.

In some areas, there have been increasing numbers of reports of apparent failures of heartworm preventive medication. These cases can sometimes be explained by factors such as poor compliance (e.g. the owner forgot to give the medication or did not give it properly), unnoticed vomiting/regurgitation of oral medication, or encountering an infected mosquito outside of the normal transmission period (i.e. in areas where it's a seasonal issue and medication is therefore not given year round). However, not all cases have clear explanations, and truly resistant heartworms have been identified.

Most of the concern has been focused around the inadvertent discovery of the "MP3" strain. For companies to be able to state that their product is effective against heartworm, they have to prove it in experimental studies using recent strains of the parasite. When the MP3 strain was used to test a potential new drug, they found out that it was actually resistant to the standard treatment.

A study in Veterinary Parasitology (Blagburn et al 2011) describes further testing that was done on this strain. The authors showed that only one of the four medications tested (imidacloprid/moxidectin) provided 100% protection in experimentally infected dogs with a single treatment.

At this point, there's limited information about clinical cases of resistant heartworm, and most of the anecdotal reports come from the central US. The MP3 strain itself was found in a dog from northeast Georgia in 2006. A big question is whether this is:

• a small, focal, regional issue
• a regional issue that's going to expand
• a wider but unidentified problem in many areas

There's no way to know for sure without surveillance, but it is cause for concern.

What does resistant heartworm mean to the average dog owner?

I think it means the days of being able to justify not testing dogs annually, even if it's certain that all heartworm medication has been given religiously since the last test, are over. Skipping annual testing was always a bit of a tenuous argument anyway, because of the potential for a dog to vomit or regurgitate oral medication, or to encounter an infected mosquito while not on medication, and it's even weaker now that resistance might be an issue.

Why is heartworm testing more important now?

It's important for two reasons. One is to make sure that heartworm is promptly diagnosed if it is present. This allows for earlier treatment before the parasites cause more damage. The other reason is to get information about whether resistant strains might be emerging in an area, which is helpful for the broader dog population. We have little information about the distribution of resistance, but if veterinarians start seeing heartworm cases in animals that have been properly treated with preventative medication, it's an indication that resistance might be developing in the area.

At this point, people shouldn't get too concerned about resistant heartworm, but we need to pay attention to the issue in case it increases or is in fact more widespread than we realize. Ongoing surveillance in different areas is needed to determine the scope of the problem, in terms of both the prevalence of resistant parasites and the impact on animal health. We need to be careful not to overreact, but at the same time we need to figure out what's going on. Pet owners need to have conversations with their veterinarians about the need for heartworm prevention in their pet, and the optimal approach to testing and prevention.

(click image for source)

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A sure sign of spring is the proliferation of classrooms hatching out chicken or duck eggs. While chicks may be cute and entertaining, they are also high-risk sources of Salmonella and some other infectious microorganisms. Numerous Salmonella outbreaks have been linked to contact with hatchling chicks, and care must be taken if teachers are considering having chicks in classrooms.

Things to consider:

• Who will be in contact with the chicks? Children under 5 years of age, pregnant women and people with compromised immune systems should not have contact with young chicks. This rules out having chicks in preschool and some kindergarten classes, however not everyone follows those standard recommendations. It's also very hard to know whether there may be immunocompromised kids in the classroom. Unless a teacher/school is sure that there are no high-risk children present, they shouldn't have high risk animals.
• Where will the chicks be hatched and raised? Is it in a contained area?
• Is the chick area easily and always supervised to ensure that rules are followed? This is important for both children and chicks, since chicks can easily be injured or killed through improper handling.
• Are protocols in place regarding safe handling and hygiene?
• Are the chicks going to be in an area where students eat?
• Are parents going to be notified in advance?
• Are there plans for sending the birds to an appropriate home when they're done in the classroom?
• Are the chicks there for a true educational purpose, or just as a novelty?

Hatching chicks can be done relatively safely in appropriate classrooms, with older children, no high-risk individuals, easy access to hand hygiene stations, appropriate protocols and proper supervision. The problem is, these aren't always (or even often) present, and inadequate thought often goes into bringing chicks into classrooms.

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I get this question a lot, from both pet owners and veterinarians. Typically, my answer is "no."

Why not?

• The two big questions I always ask are "why do you want to know and what would you do with the results?"

Sometimes people want to know their pet's MRSA status to see if the pet was the source of their infection.

• However, MRSA in pets is typically associated with MRSA in humans, i.e. if a pet is carrying MRSA, it probably got it from the owner or another close contact. Finding MRSA in a pet after someone is diagnosed with an MRSA infection doesn't mean the pet was the source. More likely, the person got MRSA somewhere else and passed it on to their pet.

Sometimes, people want to know if their pet is at risk of an infection.

• Carrying MRSA presumably increases the risk of an MRSA infection, but likely only in animals already at risk of an infection because of underlying disease or other risk factors such as surgery. The risk to the average pet from short-term MRSA colonization is probably limited. Also, if the pet was identified as a carrier, we wouldn't be doing anything to eliminate carriage, since we have no idea if decolonization therapy is effective in animals, and it doesn't seem to be needed (because dogs and cats almost always get rid of it on their own). Therefore, it's hard to justify screening for this reason. If the animal was getting ready to undergo surgery, then that might change my answer.

For me, it's also very important to consider what you'd do with the results of any test. In general, in a household where a person has an MRSA infection:

If the pet tests negative, I'd say that it doesn't 100% guarantee that the pet is truly negative, since no screening test is absolutely 100% sensitive. Also, the test only tells you the status of the pet at the time of sampling. It could have picked up MRSA five minutes after the swabs were taken. So, a negative result means the animal is probably negative. Since it's not absolutely negative and since the pet would be at risk of picking up MRSA from the infected person after it was tested, I'd recommend close attention to hygiene around the pet (especially good hand hygiene and avoiding contact with the nose) to reduce the chance of the pet becoming colonized and to reduce the risk of MRSA transmission from pet to person if the pet was actually a carrier.

If the pet tests positive, I'd say that we certainly couldn't say the pet was the source of infection. More likely, it got it from the person with the infection. Since we know that MRSA carriage in dogs and cats is almost always transient, and that they will almost always get rid of it on their own if re-exposure is prevented, I'd recommend close attention to hygiene around the pet (especially good hand hygiene and avoiding contact with the nose).

Since my response to either result would essentially be the same, why test?

Efforts are better spent on good household hygiene practices and restricting contact with high risk sites. On both pets and people, this would include the nose, as well as any sites that are infected or sites that are prone to infection (e.g. skin lesions). That's going to be much more worthwhile and rewarding than testing the pet.

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Kinkajous are strange little mammals from the Procyonidae family - the same family to which raccoons belong. Kinkajous are native to Central and South America and are occasionally kept as pets, but they don't make great pets because they are strictly nocturnal, can be cranky when woken during the day, and can sometimes be aggressive. Regardless, there is a niche pet trade, particularly in the US.

A recent report in Morbidity and Mortality Weekly Report describes detection of Baylisascaris procyonis (the raccoon roundworm) in pet kinkajous in the US, including:

• A 10-week-old kinkajou in Tennessee in which Baylisascaris procyonis was found during a routine fecal examination.
• Detection of Baylisascaris eggs from soil samples under the cages of a kinkajou breeder in Florida (the breeder from which the Tennessee animal was obtained).
• An unrelated case (11 years earlier) in which adult Baylisascaris worms were found in the intestinal tract of two adult kinkajous that died of other causes.

No human infections (i.e. cases of larval migrans) were linked to infected kinkiajous.

Baylisascaris is a parasite that's extremely common in raccoons, rare (but concerning and sometimes over-hyped) in dogs, and an extremely rare cause of disease in people. While rare in humans, it still gets a lot of attention because when disease does occur, it can cause serious neurological damage, typically in children. The damage is caused by migration of parasite larvae through the body, and through the brain. This can occur after someone swallows infective parasite eggs, which then hatch in the intestinal tract and then embark on their journey through the body.

It's unclear whether Baylisascaris is a common problem in kinkajous (like it is in raccoons) or a rare finding (like it is in dogs), since this report only describes the parasite in a small number of animals, and no larger studies of intestinal parasites in kinkajous have been reported. It would be useful to know whether kinkajous are true reservoirs of this parasite (and therefore whether we should consider all kinkajous to be carriers) or whether infection is just an unusual finding.

Overall, the public health risk is likely limited.

• There aren't that many pet kinkajous around, as far as I know.
• While Baylisascaris is nothing to dismiss, to get infected, a person still has to eat infective eggs from feces. The likelihood of transmission from a pet to a person is therefore low if good basic hygiene measures are used.
• The parasite eggs are not immediately infectious. They have to sit around in the environment before they are infectious, usually for 2-4 weeks. Therefore, prompt removal of feces and careful attention to basic practices like hand hygiene should greatly reduce the risk of transmission.
• Routine testing and deworming of pet kinkajous should reduce the risk even further.

What does this mean for pet kinkajou owners? Not a lot beyond what would normally be recommended. Pet kinkajous should have good veterinary care and regular fecal examinations. Regular deworming should be discussed with the attending veterinarian, and good hygiene practices should be used to avoid contact with feces, especially old feces.

Photo credit: Robrrb at en.wikipedia

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When a particular animal species or breed gets a lot of attention, such as through a popular movie or TV show, there's sometimes a major increase in people wanting one as a pet. The proliferation of Dalmatians after 101 Dalmatians, and people buying Jack Russell terriers in response to Eddie from Frasier are only two examples. Sometimes the trend is fine, but it can result in problems when people get breeds or species that really aren't right for them (this was a big problem with the Dalmatians), and with puppy mills pumping out large numbers of poor quality animals to meet the demand. The problems can be even worse when an exotic species is involved.

Concern has been expressed about the potential for this to occur following the success of the animated movie Rango. The movie features a chameleon, a fascinating reptile but also one that is not that easy to properly maintain in captivity and, like all reptiles, carries a risk of Salmonella transmission to household members. 

PETA and some other groups have expressed concern about a PetSmart promotion whereby people can get a $10 discount on reptiles if they bring in a Rango movie ticket stubs. 

Any increase in demand for chameleons resulting from this promotion will be trouble, because:

• Odds are most of the animals will not do well if purchased on a whim by someone who isn't adequately prepared to take care of them.
• Smuggling or legal importation of wild-caught chameleons will probably increase, with the associated very high death rates during the collection and shipping process.
• Chameleons may end up in households where reptiles are not appropriate, such as those with kids under five years of age, elderly individuals, pregnant women or people with compromised immune systems.

Hopefully the concerns are unfounded, but anyone considering purchasing a chameleon needs to carefully research the care requirements, be aware of the risk of disease transmission in the household, and should look for ethically sourced (i.e. captive bred and properly raised) animals.

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In Canada, rabies testing and surveillance is performed by the Canadian Food Inspection Agency (CFIA). National data for 2010 are now available and indicate there were a small number of cases in domestic animals, with more in wildlife, for a total of 123 cases.

Dogs: There were three cases, all in Saskatchewan.

Cats: Four cases, three in Manitoba and one in Alberta.

Horses: One rabid horse in Manitoba.

Cattle: One, from Manitoba.

Skunks: 60 cases, 33 in Manitoba, 17 in Saskatchewan and 10 in Ontario.

Bats: 48 rabid bats, most in Ontario (29) but also in BC, Alberta, Saskatchewan, Manitoba, Quebec, New Brunswick and Nova Scotia.

Foxes: Six from the Northwest Territories or Nunavut.

No rabid sheep, goats, raccoons (down from 58 in 2007), wolves or other species.

Manitoba seems to win the 2010 rabies prize, while Newfoundland and Labrador, Prince Edward Island and the Yukon had no cases.

As with any disease surveillance, these numbers underestimate the scope of rabies. For an animal to appear on the list, rabies had to be considered and testing performed. So, for  wildlife, it's a massive underestimation of the number of cases, since most affected wildlife don't get tested. Wildlife testing (and testing in general) is typically only done when there has been the potential for human exposure. Domestic animal cases are probably a fairly close representation of the status of rabies in pet and farm animals, since it's reasonably likely that a domestic animal with rabies would be identified as such and tested (although certainly cases can be missed or neglected). As with wildlife, there is probably an under-identification of rabies in feral/stray dogs and cats, since testing would only be done on these animals if they are caught and if there was potential human exposure.

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An Irish study has reported a high rate of Salmonella contamination in pig ear treats. Various earlier studies have identified Salmonella in pig ear treats, and human infections have been associated with contact with such treats. Recommendations for processing and handling of pig ear treats have been made and have hopefully reduced the likelihood of contamination, but there's no information about adherence to these recommendations.

In the most recent study, published in Food Research International (Adley et al. 2011), researchers purchased 102 pig ears from 4 pet shops in Limerick City, Ireland. Salmonella was detected in 28% of samples. A variety of different Salmonella types were found, including antibiotic resistant strains and types that are common causes of disease in people.

Interestingly, all of the contaminated treats were from 2 of the 4 stores. The two negative stores only sold treats sourced from within the European Union, and one of them only sold pre-packaged treats. The other two stores sold treats sourced from the EU and Brazil, and sold some in bulk bins. All positive treats were from the same distributor, and all were from bulk bins.

The high prevalence of Salmonella in these treats is concerning, particularly in light of standard guidelines for processing such treats and and EU regulation that if treats are not Salmonella-free, they must have less than 1 Salmonella bacterium per 25 g of product.

Contamination of bulk bin treats isn't surprising, as I mentioned in a post just the other day. Bulk bins allow for cross contamination, and a single positive treat (or a single contaminated hand going into the bin) can result in contamination of many other treats. Also, picking treats out of a bulk bin can potentially contaminate consumers' hands, and there's an additional concern that bulk bins are often kept at a level where young children (a high risk group) can access them.

Contact with Salmonella in pig ear treats is a risk, and people should wash their hands after any contact with a pet treat. Avoiding bulk bin treats is a good idea. Purchasing irradiated and individually packaged treats should also help reduce the risk. Unfortunately, stores do a lousy job of notifying people about the risk. As the paper states "We recommend public awareness advertising in pet shops to alert pet owners of the risks associated with pig ear pet treats and hygiene practices that should be followed."

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Glanders, a very serious disease of horses, donkeys and mules caused by infection with the bacterium Burkholderia mallei, has made the news again in a rather unusual manner – it has been reported as the cause of an outbreak in lions and a tiger at an Iranian zoo in Tehran.

The story goes that two Amur tigers arrived at the Tehran zoo from Eastern Russia in April 2010 as part of an exchange program between the two countries. The tigers were supposed to be used to help restore the tiger population in northern Iran on the Miankaleh nature reserve, but their living quarters there were apparently still not ready, and thus they were being kept at the zoo. One of the tigers died in December 2010.

And that’s were the story starts to get a little dicey. The Iranians claim the tigers were imported already carrying the disease, and that the last case of glanders at the zoo was 50 years ago. The tigers had already been at the zoo for eight months - although the incubation period for glanders can be months in some cases, it is normally only weeks. The Russians of course insist that the tigers were completely healthy when they were transferred – they’d been thoroughly examined and quarantined prior to being moved. (This makes the most sense to me, since transporting an animal such a long distance is a major stress and increases the risk of illness, and transporting an animal that is already sick would be even more risky. Not a chance I would take with two members of a species of which there are fewer than 900 individuals left in the world.) They also pointed out that a sick tiger from the cold regions of Russia would be much more likely to succumb to illness during the very hot Iranian summer, not during the winter.

Another report said that three lions at the zoo also died from glanders in the last two months, and subsequently another 14 lions were diagnosed with the disease, all of which were put down by the authorities. The main concern seemed to be the spread of the disease from the big cats to the feral cat population, and then to the human population. This second report states that “the tiger died after being fed contaminated meat, though it is possible it could also be related to the glanders.”  Yet another report said that the tiger was infected with feline immunodeficiency virus (FIV - the feline equivalent of HIV).

Facts to keep in mind:

• Glanders is an highly contagious disease, and highly fatal (B. mallei is even classified as a Class B bioterrorism agent).
• Animals that do recover from the disease can become long-term carriers of B. mallei, and are a risk to other animals (and people). Prompt euthanasia of affected animals is therefore often the primary means of controlling outbreaks (but the bacterium is susceptible to antibiotics).
• The infection can be transmitted to other animals (and people), usually through close direct contact or contact with oral and nasal secretions and discharge from skin ulcers. It can also be transmitted by eating tissues from infected animals.
• The bacterium is killed by most disinfectants, and UV radiation (sunlight).

Glanders can affect species other than equids, including people and cats, however there is very little information available about glanders in any felids, let alone lions and tigers. Theoretically it might be possible for the disease to spread from the zoo animals to feral cats and then to people, but I don’t know how many feral cats are brave (or stupid) enough to wander into a lion enclosure. There’s also a possibility that a glanders-positive feral cat may have infected the zoo cats (but again, it would have to be very brave, or very stupid). It is also unclear what tests were used to confirm that the big cats were infected with glanders, and it is unknown if other animals at the zoo have been tested. Since this is typically a disease of equids (and has also been found in goats and camels), I would certainly be checking these animals first.

The big question is, where did the glanders come from in the first place? It seems unlikely that the tigers brought it from Russia, when the disease is actually endemic in Iran (even though they’d had no diagnosed cases at the zoo for many years). Is there a carrier animal in the zoo? Were the animals infected by eating contaminated meat? Was it brought in by feral cats?  The source needs to be identified and addressed or animals will continue to be infected, which is particularly bad news for the kinds of rare species that may be found in a zoological collection. Some more details about the testing would also be appreciated – given the severity of this disease, and the severity of the consequences for positive animals (euthanasia), one needs to be as sure as possible that these animals are infected with B. mallei and not something else.

Photo: Amur Tiger (Panthera tigris ssp. altaica) (click image for source)

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An upcoming article in the journal Emerging Infectious Diseases entitled "Zoonoses in the bedroom" has attracted some attention in the press. I haven't been able to access a copy yet, but will probably write about it soon. However, one article that was written about the paper had a pretty weak lead-in piece:

"Nikki Moustaki knew something was wrong when she got strep throat for the sixth time in a year. Her doctor wanted to take out her tonsils. But Moustaki, an otherwise healthy 30-something, was determined to uncover the source of the infection. "I saw a bunch of specialists, and one suggested my dog might be a carrier," said Moustaki, a New York City-based dog expert and trainer. "I had never thought of that. When you think of contagious diseases in dogs you think of rabies and ringworm, you don't think of strep." After four walks a day on the streets of Hell's Kitchen, Moustaki's dogs -- a schnauzer called Pepper and Ozzie, a schnoodle -- would curl up beside her in bed. Following her doctor's surprising suggestion, Moustaki started cleaning Pepper and Ozzie's paws with baby wipes after each walk. And she's been strep-free ever since."

While it's good to see the potential role of pets in human disease considered (since it's often overlooked), this is a example of the opposite end of the spectrum: implicating pets with absolutely no evidence, and actually, contrary to all available evidence. Saying that cleaning her dogs' feet prevented her from getting strep throat makes little sense on many levels. Firstly, if it actually made the difference, then she wasn't really getting strep from the dogs, it was coming into the house on the dogs' feet from the ground outside. There's no evidence the outdoor environment is a relevant source of strep. If strep was present on the dogs' feet, it would have to make it to her nose and mouth, and that degree of contact is hopefully unlikely (and if present, it would be associated with a lot bigger concerns that strep). Further, despite various studies, there is no evidence that dogs are even rare reservoirs of Group A Streptococcus, the cause of strep throat. Recurrent strep throat in people is caused by repeated exposure to infected people.

Like I said, it's good to see recognition of the potential role of pets. The next step, however, has to be looking for the evidence. It's not hard to find a few good references that talk about the role (or lack thereof in this case) of pets in human strep infections. Implicating the pet and recommending a rather bizarre foot hygiene regimen isn't really helping anyone.

Is it just coincidence that the infections have stopped in this woman? Probably. Recurrent infections don't tend to go on forever. However, maybe her increased attention to cleaning her dogs' paws also led to her paying more attention (consciously or otherwise) to her own hygiene practices, which would have probably played a greater role in disease prevention.

(click image for source)

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An interesting paper in the journal Emerging Infectious Diseases (Page et al. 2011) describes an impressively large effort to study the effect of anthelmintic (dewormer) baiting on parasite contamination at raccoon latrines sites in Indiana.

Raccoon latrines can be highly contaminated with various parasites, because raccoons congregate at these sites and use them as "communal toilets." Of all these parasites, the raccoon roundworm, Baylisascaris procyonis, gets the most attention.  It is very common in raccoons, but it is also a very rare cause of disease in people who swallow the infective parasite eggs from the environment.  In some of these people the parasite larvae can cause very serious neurological disease which can be very difficult to treat.

In this study, the research team identified 559 raccoon latrines in north-central Indiana. They removed debris from the areas and used a torch to help kill the parasite eggs that were there (this is one of the very few effective ways to kill the very hardy eggs of Baylisascaris). At a selection of latrine sites, they also collected baseline fecal samples. After this was all done, they distributed dewormer (pyrantel pamoate) baits in half the areas once a month (leaving the other half of the areas as controls). They then collected fecal samples at all the latrine sites approximately 6, 12 and 18 months later.

Fecal samples were tested for B. procyonis eggs. Also, they captured mice from some of the study patches. Like people, mice are intermediate hosts for B. procyonis, and they can be infected in the same manner, so researchers looked for B. procyonis larvae in the brains of the mice.

Overall, they tested 1797 fecal samples. In the first round of sampling, 33% of samples contained B. procyonis eggs. The prevalence of eggs decreases significantly (3-fold) after baiting by the first recheck, and stayed at that level throughout the study. By the one-year sample time, there was also a significant decline in B. procyonis larvae in the brains of mice (27% vs 38%).

This impressive study shows the potential impact of controlled and somewhat practical interventions on the presence of some concerning microorganisms. Certainly, no one is going to be able to treat all raccoon latrines with a torch. However, dewormer baiting might be a consideration in areas that are close to human populations, along with other control measures. Dewormer baiting could be relatively cost-effective in this case. It won't eliminate the problem, but it might help reduce environmental contamination and the associated potential for human and domestic animal exposure.

More information about Baylisascaris and raccoon latrines is available in our archives.

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Miami Beach officials, disturbed by reports of a hookworm outbreak, have taken a rather unique approach to the problem: they've created a cat and cat poop map.

This fall, several cases of cutaneous larval migrans were reported - and highly publicized - in the Miami Beach area, something that is of particular concern for a tourist city that doesn't want people thinking the city's beaches are biohazardous.

Cutaneous larval migrans is a skin condition caused by migration of hookworm larvae through the skin. Dogs and cats can be carries of hookworms and pass eggs in their feces. Larvae then hatch from these eggs and can penetrate the skin (of people and animals alike) after being in the environment for a few (usually 2-9) days. If someone has contact with infectious larvae, such as by stepping on them while bare foot on a beach, the larvae get into their skin and start migrating, causing this very itchy skin condition.

Feral (stray) cats are the main problem in Miami Beach. Stray cats and beaches are a bad combination, since stray cats tend to have high rates of hookworm carriage, they often defecate in sand on the beach, and of course people often have direct contact between bare skin and beach sand. Identifying where stray cats live (and poop) is important for disease control and public education. "We needed to identify where the cats are eating — and where they're pooping — to address this problem" stated a program organizer. To do this, city sanitation workers were given GPS devices and instructions to go find cats. Data were uploaded into a mapping system, and areas where cats tend to congregate were identified. Not surprisingly, certain areas of sane dunes are being used as industrial-sized litterboxes by the cats.

This type of information can be used in several ways. It can be useful for evaluating cat populations: where they are, where they go, and what happens to them over time. It can help identify areas where the cat population needs to be addressed through measures such as trap, neuter and release programs (as are being used in Miami Beach). It can also help with development of targeted education programs, by putting up warnings in heavily cat- and cat poop-infested areas. City health officials think that the combination of tracking, the increased spay/neuter program and targeted warnings to sunbathers have helped staunch the outbreak.

Image source: http://blogs.miaminewtimes.com

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Pseudorabies is one of those diseases with a really bad name (although it's a pretty bad disease too). It has nothing to do with rabies. Rather, it's caused by a herpesvirus; porcine herpesvirus 1. The name "pseudorabies" presumably came into existence because it causes neurological disease that, in some cases, can look like rabies.

Pigs are the reservoir of this virus, and it's a very important cause of pig disease in some regions. Spillover infections can occur in many different mammals, including dogs, cattle and sheep, and infections in these species are typically fatal.

Pseudorabies is not as widely distributed internationally as rabies, but it is present in wild boars in many regions, including many European countries. Infections in dogs are sporadically reported, typically in hunting dogs infected by contact with wild boars.

Recently, a case of pseudorabies (also known as Aujeszky's disease) was diagnosed in a dog in Luxembourg, the first diagnosis of the disease in the country since it was identified in domestic pigs in 1999. (Infections in wild boars were suspected in late 2009 but not confirmed.) Few clinical details are provided in the report to the OIE, beyond the fact that the dog died. Contact with "wild species" was listed as the source of the infection, which presumably was contact with wild boars.  

Unlike rabies, pseudorabies is not a significant concern in people.

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Many people think of rabies as a very rare disease primarily associated with wildlife, however canine rabies kills tens of thousand of people each year, making it a leading cause of infectious disease deaths in some areas. China is an example of such a region, and rabies is a serious problem throughout much of the country. For example, last month 33 people died of rabies in Guangdong province, according to the the Provincial Health Bureau. That means that there were more deaths from rabies than tuberculosis in the region (there were 80 deaths from AIDS, 33 from rabies and 14 from TB).

The frustrating part is that the vast majority of rabies infections can be prevented with basic medical care, consisting of timely administration of rabies post-exposure prophylaxis, and vaccination of both feral and pet dogs.

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A recent paper about rabies post-exposure treatment in animals (Wilson et al, J Am Vet Med Assoc 2010) also contained some interesting information about rabies vaccine failure in pets. The study, which looked at data from more than 1000 animals in Texas from 2000-2009, mentioned a vaccinated 15-month-old cat that developed rabies. It had been vaccinated at 5 months of age and was not yet due for a booster, which would have been required at 17 months of age. 

Rabies was also diagnosed in a dog and cat that had been vaccinated but were overdue for their boosters. Both initially received one dose of a 3-year vaccine, but they did not received the booster that is supposed to be given 1 year later. (Even with 3-year vaccines, pets are supposed to be given their first booster (i.e. their second dose of vaccine) after 1 year, before moving to getting boosters every 3 years). The dog was vaccinated 2 years and 9 months earlier. Twelve days after being exposed to a rabid skunk it was given a booster, but it developed rabies nonetheless and died 8 days later. The cat was vaccinated 2 years and 3 months earlier.  It apparently did not receive a booster after it was exposed to rabies, and subsequently also died of rabies.

Another six dogs and three cats that were vaccinated developed rabies, but all of these were overdue for their booster or had been vaccinated less than 30 days before rabies exposure. These were therefore not considered vaccine failures.

This information should not be taken as an indication that rabies vaccination is not useful or that current vaccination protocols are inadequate. This involves a very small number of animals, and only one that was properly vaccinated. Rather, it should be a reminder that vaccination is not infallible and that the possibility of rabies cannot be summarily dismissed just because the animal has been properly vaccinated.

(click image for source)

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Tuberculosis (TB) is a very important public health issue.  Caused by the bacterium Mycobacterium tuberculosis, TB is likely the most widespread human infectious disease. Although it primarily affects people, it can rarely affect various animal species as well, including pets. The relevance of dogs to human TB is unclear: we know dogs can (rarely) be infected by M. tuberculosis, but it remains uncertain whether infected dogs pose a risk to their human contacts (presumably dogs become infected in the first place from one of their human contacts, who is therefore also a source of exposure to other people).  There is little information available about this risk.

People working in the veterinary field are at increased risk of exposure to many infectious agents. For this reason, there are standard practices that are (or at least should be) used to reduce unexpected exposures. A good example of such an unexpected exposure and the consequences thereof is presented in a case report from Switzerland recently published in Veterinary Microbiology (Posthaus et al 2010). 

The report describes a seven-year-old Ibizan hound that was referred to the University of Bern's small animal clinic because of lethargy and vague neurological abnormalities. The dog was originally imported from an unknown country in southern Europe and was adopted from a shelter at two years of age. The animal was ultimately euthanized after it became very ill, with severe neurological disease and respiratory arrest. On necropsy, masses were identified in the brain and liver, and infection with Mycobacterium avium complex was suspected. However, subsequent testing identified M. tuberculosis, triggering an investigation of all human and animal contacts.

Testing included a blood test called the IGRA, which detects people who are either infected or exposed. The test can't differentiate between a recent infection and a past infection/exposure, so a positive result needs to be interpreted in conjunction with an evaluation of the person's history, to determine if previous exposure is likely.

The Ibizan's two owners tested negative. None of the veterinary clinicians that worked with the dog before its death were positive (or more specifically, none were positive and the result thought to be related to exposure to the dog), including the three people who were involving in intubating the animal (placing a breathing tube - a potentially high-risk procedure in an animal with TB). In contrast, six pathologists who were involved with the necropsy were positive, including the three who were most closely involved. Two of these individuals had no apparent risk of previous exposure, so infection from the dog was suspected

Additionally, a cat that lived in the house tested positive.  Because of the potential that the cat was infected and concerns about transmission to people, it was euthanized.

This case had some rather interesting findings:

• TB infection in a dog. Clinical disease caused by TB in dogs is rare, and signs can be quite vague, as in this animal. This was not a case of classical respiratory tract TB.
• Infection occurred in the dog well after its presumed time of exposure. The source of infection was unknown, but given the family's history, it is reasonable to suspect that the dog arrived in the country already infected. This shows how diseases like TB with potentially long incubation periods can catch you by surprise. The dog was treated with high doses of steroids initially, possibly triggering re-activation of dormant TB because of immunosuppression.
• Infection of people with TB while conducting a necropsy, demonstrating the occupational risks that can be involved in such procedures. The use of power tools to open the skull is commonplace in veterinary pathology, and may have played a role here by aerosolizing the bacterium. The institution has now changed standard necropsy practices to reduce the risk of subsequent exposures.
• There was no apparent infection of any people when the dog was alive. Presumably, it was not shedding much, or any, of the TB bacterium in its respiratory tract.
• Possible transmission of TB from the dog to a cat. However, it can't be stated with certainty that the dog and cat were not infected by the same unknown source after the dog was adopted. Testing was not performed on the cat after it was euthanized, so it is possible that it was not infected with TB, but with another related Mycobacterium.

This case doesn't indicate that we are dealing with a new issue. Rather, it is possible that there are many more dogs that are apparently healthy but infected with TB. These animals may pose little risk to people, especially if they don't have respiratory disease, but it's an area where information is limited.  More attention needs to be paid to the risk of interspecies transmission of TB, how to identify it, how to reduce the risk, and how to manage infected animals. There's debate about whether exposed but healthy animals like the cat in this case should be euthanized because of the potential (but completely unknown) public health risk. Without good research data, we can't provide reliable answers to questions about the risks.

Image: Ibizan Hound (click for source)

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A dead otter was found floating in a pond in Florida near the site of a recent otter attack that was captured on video. Testing confirmed that the animal was rabid. It's impossible to determine whether this is the same otter that attacked the teenager in Boca Raton last week, but it's likely, and shows that rabies post-exposure treatment of the victim was a good decision.

Numerous rabid otters have been identified in Florida in recent years. I haven't seen any information about the viral types that have been involved or how it is thought that otters are becoming infected. Regardless, these incidents should be a reminder to stay away from wildlife, and to consider rabies exposure any time someone has been bitten by a wild mammal.

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A teenager who was filming an otter he spied in a pond now knows more about rabies than he probably ever wanted. The 19-year-old shot the video from the bank of a pond, watching the otter innocently swimming around. After a brief stare-down, the otter did another quick swim, then ran onto shore and attacked!  And it was all caught on camera and displayed to the world via YouTube.

This is the third recently-reported otter attack in the area. This type of behaviour obviously isn't normal, and rabies has to be a concern. Rabies has been previously identified in marauding otters in Florida, and since this otter got away, you have to assume that it was rabid. Accordingly, the victim is undergoing rabies post-exposure treatment.

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Humane societies and shelters are often overwhelmed by the number of animals that come in. It's pretty uncommon to see much (if any) empty space in most shelters, and overcapacity shelters lead to increased risk of disease transmission, outbreaks and suboptimal care of the animals that are there.

One way of helping deal with overcrowding is fostering animals to people's homes for periods of time. Typically, foster homes take animals when shelters are at capacity, or take specific animals such as nursing cats, which are more difficult to care for properly in a shelter.

Most places have protocols for fostering, but they're not always very comprehensive and they don't always adequately cover some important areas. If you are thinking about fostering shelter animals, you need to think about the risks and whether you can manage them.

Are there people in the household that are at increased risk of infection?

Fostered animals should be assumed to be at higher risk of carrying and transmitting various infectious diseases. They can have high rates of carriage of various intestinal bacteria and parasites, along with a host of other microorganisms (e.g. ringworm). They may also be more likely to bite and scratch, not necessarily because they are aggressive, but often because they are young animals that may do so when playing. They may also be more likely to poop in the house.

Households with children under the age of 5, elderly individuals, pregnant women or people whose immune systems are compromised are at increased risk of various infections, both in terms of the likelihood of becoming infected and the likelihood of developing more severe disease. Households with these types of individuals should not foster animals. They are much better off having their own lower-risk pets.

Are there any "resident" pets in the household?

You might expect that someone willing to foster animals would also have their own pets, but that's not always the case. Non-pet owners are actually ideal, since this negates any risk of diseases being spread from or to household pets that live there long-term. However, it's more typical that foster homes also have such resident pets.

Are there any pets in the household that are at higher risk for infection?

As with people, there are some animals that are at increased risk of infection. These include the very young, very old, pregnant and pets with compromised immune systems. The latter group would include pets with chronic illnesses, those being treated with high doses of steroids for various diseases, animals with cancer, animals with diabetes, and a range of other issues. People owning a pet that fits into one of these categories should not foster animals because of the risk to their own pet. 

How do you reduce the risks associated with fostering animals?

• May sure there are no high risk people or pets in the household.
• Make sure the shelter or organization knows what they are doing. Make sure they have a clear protocol that says who will be fostered and how it's done.
• Look at the animal before you get it. Visit it at the shelter. See if it looks healthy. If you have any questions, make sure it's examined by a vet before it reaches your home.
• Use good hygiene. Wash your hands regularly. Properly clean up feces and clean litterboxes regularly.

If you have pets of your own:

• Make sure they are vaccinated and on an appropriate parasite control program.
• Keep the new animal away from your pet at the start. That lets you find out more about the animal, and it gives you more time to see if there are potential infectious disease concerns.
• Do a controlled introduction of the new animal. Slow, supervised introduction of the animals can reduce the risk of bites or scratches.

Fostering is a good way to reduce pressures on humane societies and shelters, and to provide better care for some animals, like pregnant animals or those with young kittens/puppies. A good fostering program can be set up with limited risk to all involved, but infectious disease risks can never be completely eliminated. By accepting a new animal into your house, you increase the risk of exposing yourself and anyone else (human or animal) to infectious diseases. That's just a fact of life.

(click image for source)

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As multidrug-resistant bacteria such as methicillin-resistant Staphylococcus pseudintermedius (MRSP) become more common in pets, there are increasing questions about how to manage animals that carry them. A particular issue is what to do with carriers - animals that don't have any sign of disease but still carry the bacterium.

A small but increasing percentage of healthy dogs and cats are currently carrying MRSP in their nose or intestinal tract. The rates appear to be shooting up in most areas, and I suspect that the current carriage rate in a lot of regions is above 5%. In some groups of animals, particularly those that have received repeated courses of antibiotics, rates are likely much higher.

Back to the initial question... what to do with MRSP carriers?

Well, in some ways, we want to limit their contact with other animals to reduce the spread of the bacterium. However, we also have to realize that this is now a rather common bacterium, and it doesn't cause infections in the majority of animals that get exposed, and it is very rarely a problem in people. That doesn't mean we should ignore it, but it's a lot easier to justify being very strict with a bug that:

• is readily transmitted to people and can cause disease in people.
• is rare in the dog population.
• is highly infectious.
• usually causes disease when an animal is exposed.

These aren't the case with MRSP. It's still certainly a serious concern, but where do we draw the line between being proactive and being impractical?

Back to the title of the post... what to do with MRSP-positive dogs that go to dog parks?

It's a good question, and I don't have an answer in which I'm 100% confident. The paranoid infectious diseases part of my brain wants to keep MRSP carriers away from other dogs to reduce transmission. But, the practical part of me recognizes that parks are probably a limited source of transmission overall, that there are probably greater risk factors for the increase in MRSP, that we have no idea whether short-term contact such as meeting in passing at a dog park can result in efficient transmission, and that going to the park is an important activity for many people and their dogs.

Anyone that takes their dog to a dog park needs to understand they are increasing the risk of infectious disease transmission to (and from) their dog. This includes a wide range of bacterial, viral, parasitic and fungal diseases, not just MRSP. In fact, I think there are other pathogens that are a bigger concern from dog park exposure.

Should MRSP dogs be keep away from dog parks?

• When they have an active infection and are presumably shedding larger numbers of bacteria: Yes.
• When they are just carriers: Probably not.
  

How can I say that when I keeping talk about how big a deal MRSP is?

• It's a big deal, but it's mainly a big deal in specific circumstances, such as in dogs undergoing surgery, dogs with underlying skin disease and dogs that are exposed to antibiotics. There is no such thing as a no-risk dog, but the individual risk for a healthy dog is probably very low.
• You have to live. You can do the Howard Hughes model of infection control and barricade yourself in your room, or you can live life. Yes, that increases risk. But, we do things to contain that risk as much as possible, such as keeping sick dogs away from parks (to prevent both transmitting and picking up microorganisms), reducing antibiotic use and using good general hygiene practices.
• You don't want to purposefully infect other dogs, but the small number of known MRSP carriers is dwarfed by the thousands of dogs that are unknown carriers.
• In some respects, MRSA is the human version of MRSP, and it's a huge health problem. However, MRSA carriers are not locked away. We realize they are transmission sources but we focus efforts on carriers only in high risk situations, such as hospitals. Could we greatly decrease MRSA carriage in people by aggressively testing, treating and quarantining? Sure. Is it worth it? That's pretty questionable.

I never want to give the impression that we are being lax with an important infectious disease, but I just don't have the evidence (or anecdotes) that restricting park access for carriers will do anything for MRSP control, especially since known MRSP carriers probably represent 0.0001% of all MRSP carriers.

What can you do to reduce the risk of transmitting or acquiring MRSP at the park?

• Pick up feces. Dogs can shed MRSP in feces, and this could be the most important route of transmission given how some dogs like to nose and eat feces (my dog being the poster child for that particular habit).
• Watch your dog closely so it doesn't eat feces (or at least is less likely to).
• Don't let your dog have contact with an animal with any signs of an infection, particularly a skin infection.
• Try to limit nose-nose, nose-bum contact (of the dogs... I assume you're limiting that type of contact between yourself and other dog walkers).
• If you have a dog that is high-risk for getting an infection, consider keeping it away from the park, reducing the amount of time it spends in the park or limiting off-leash time. This includes dogs with wounds, dogs that have recently had or are going to have surgery, dogs with active skin disease, dogs on immunosuppressive therapy (such as steroids), and dogs on antibiotics, among others.

More information about MRSP can be found on the Worms & Germs Resources page.

(click image for source)

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I recently had a rabies exposure and treatment question that's worth discussing. It was from a person in India whose young child had potentially been exposed to rabies. The child had a wound on her hand and a stray dog licked the area. It wasn't reported to the parents until a little while later. Three doses of rabies vaccine were obtained and the vaccine series was started a few days after the potential exposure.

Here are some issues:

• Was this child actually exposed? It's hard to say. It's probably unlikely that rabies virus was inoculated into the child in a situation like this, with relatively minor skin lesions and fairly brief contact with the dog. However, contact of saliva from an infected animal with broken skin is a potential route of infection so, even if it's unlikely, you have to err on the side of caution and consider the child exposed.
• Standard recommendations for post-exposure prophylaxis are 4 doses of vaccine on days 0, 3, 7 and 14. Three doses might be effective but it's hard to have confidence in it, especially when dealing with an almost invariably fatal disease. Trying to get ahold of a 4th dose would be best in a situation like this.
• It doesn't appear that rabies antibody was administered at the start. Standard protocol is to give anti-rabies antibody with the first vaccine dose. This provides an antibody boost and early protection while the vaccine is taking effect. The antibody can still be used even if it wasn't given with the first dose of vaccine, as long as it's within the first week. After that, it's assumed to have limited effect because antibodies from vaccination would be increasing. It's probably more important with serious bites and bites near the head and neck, where the onset of rabies can be earlier, but getting a dose of antibodies within the first 7 days would still be recommended.
• Did the dog actually have rabies? That's the big question. When someone is potentially exposed, the best thing to do is to identify and quarantine the biting dog. If the dog had rabies and was shedding rabies virus in saliva, it will show signs of rabies within 10 days. Therefore, if you quarantine the dog and it's healthy after 10 days, it didn't have rabies and no post-exposure treatment is necessary. In this case, it's a stray that was known in the area, and it seems the dog was still around and healthy 15 days after the exposure.  So, as long as there is 100% confidence that the dog is actually the same one, then post-exposure treatment is not necessary. The trick is being 100% confident that it's the same dog.

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A somewhat strange report from MSN News India describes measures that are being considered following an outbreak of salmonellosis that killed 3 tigers at Bannerghatta Biological Park.  The zoo authority is investigating whether tests used by the Indian army to detect Salmonella in milk and milk products could be used to detect Salmonella in meat.

Testing of meat for Salmonella is a reasonable consideration, but it really depends on how often meat samples are contaminated.

• If most meat samples have Salmonella, what will be done with the results and the meat? The cats have to eat, and unless they have a plan to throw out all positive food or do something to it eliminate Salmonella (like cooking it), testing might be of limited use.
• Also, if Salmonella is usually there at low levels and problems only occur with sporadic high level contamination, or contamination with particularly virulent strains, then using a test that just says "Salmonella yes" or "Salmonella no" may not help much.

It is also reported that "the authority is also in talks with some firms to come up with a microwave which has the capacity to kill microbes in 300-400 kg of meat at a time."

• This is questionable since it's probably a lot of expense to develop a large microwave, and particularly since microwaving is not a reliable method of killing Salmonella. If there is a need to treat the meat to kill Salmonella, there are more reliable measures, such as cooking in a conventional oven, irradiation or high pressure pasteurization.

Another bizarre aspect is someone from the zoo authority stated "In Canada, when 7,000 pet dogs died on being fed infected beef last year, some firms there came up with a microwave with the capacity to kill microbes in 500 kg of beef in three to four minutes. We are exploring the possibility of similar technological innovation being implemented here, for which we are in talks with some technicians".

• I have no idea what this guy is talking about. I am not aware of any outbreak killing 7000 dogs in Canada (and if it really happened, I'm pretty sure I'd be well aware, if not in the middle of it).

On the positive side, all of the tigers that survived have now completely recovered and no new cases have been identified.

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The UK's Health Protection Agency is warning families who own reptiles about the risks of Salmonella, following the diagnosis of salmonellosis in 9 Merseyside children in the past 6 months. All the affected kids had direct or indirect contact with reptiles. Three of them (all less than three years of age) were hospitalized. One of them, an infant who was infected at four weeks of age, is still sick five months later.

Salmonella is commonly found in or on healthy reptiles. All reptiles should be considered Salmonella carriers, and handled accordingly. Standard guidelines are that children under the age of five, along with immunocompromised individuals, the elderly and pregnant women, should avoid contact with reptiles. The reason for this is clearly evident here, with the bacterium having caused serious illness in these young children.

Thinking that you can eliminate the risk in a high-risk household by making sure the high-risk person  never handles the reptile isn't adequate. There are numerous reports of Salmonella infections in people who never had direct contact with the reptile.  Salmonella can be spread from the reptile's enclosure to other parts of the house, resulting in indirect infections. 

Reptiles can make great pets (I used to have tortoises and turtles). However, reptiles are responsible for a large and disproportionate number of Salmonella infections in people, and high-risk households should not have reptiles. People with reptiles need to take basic infection control measures seriously, including:

• Washing hands after contact with reptiles.
• Never cleaning aquaria or terrariums in kitchen or bathroom sinks.
• Never bathing or soaking reptiles in the bathtub, or kitchen or bathroom sinks.
• Keeping reptiles confined to their enclosures and not allowing them to roam the house.

More information about turtles and Salmonella can be found on the Worms & Germs Resources page.

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The California Veterinary Medical Association has published recommendations for dog park safety. The document, entitled "Dog parks harbor risks as well as fun" emphasizes the benefits of park visitation but points out some risks and recommended precautions. Some of the risks associated with park visits include bites, scratches, and exposure to various infectious diseases.

Some basic and practical precautions that are recommended include:

• Ensure your dog's vaccination status is current.
• Make sure your dog is socialized and behaves well around people and other animals.
  
• Monitor your dog closely.
  
• Avoid mixing small dogs and big dogs.
  
• Bring water for your dog to drink.
  
• Clean your dog's paws when you leave the park (I'm not sure that one's very useful).
  
• Have your veterinarian check your dog regularly for parasites (and other infectious diseases or risk factors).
• Talk to your veterinarian about any (other) precautions you should take.

Overall, the document provides some useful and very practical information. A few things I would add:

• Keep your pet away from the park when it's sick.
• Make sure you promptly pick up dog poop and dispose of it properly.
• If it's an off-leash park, spend a few minutes watching the other dogs that are there before deciding whether to let your dog off its own leash.
• Make sure your veterinarian knows that your dog goes to the park if it becomes sick. There are some diseases that are more likely in dogs that visit parks, and outbreaks can also be associated with parks.  Knowing that your dog has access to a dog park might be an important part of the diagnostic process. As well, knowing that you visit the park regularly might change your veterinarian's recommendations for vaccination and deworming.

(click image for source)

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Veterinarians are reporting a potential cluster of leptospirosis cases in dogs near Lake Aquitaine in Mississauga (Winston Churchill Blvd. & Derry Rd. area). Leptospira gryppotyphosa has been confirmed in one dog, with other cases being suspected but not confirmed because owners declined testing.

Leptospirosis is a bacterial infection caused by different types Leptospira spp. These bacteria like to live in water and in moist conditions, and infections in dogs most often result in kidney disease. The bacterium is shed in the urine of infected animals. Leptospira gryppotyphosa is mainly found in wild voles, raccoons, skunks and opossums, and these animals can infect various environmental areas. Any animals exposed to outdoor environments in endemic areas can become infected from ingesting infected water or from contact of infected water with the mouth, eyes or nose, or cuts or other broken skin.

People in the area where these cases have been found should take particular care and probably avoid letting their animals wander into the water or wet areas. A vaccine is available to reduce the risk of leptospirosis, including disease caused by this Leptospira type. Vaccination of pets that are exposed to water or wet habitats in areas where lepto is present is a good idea. People in the Lake Aquitaine area should be particularly vigilant and vaccination of pets would be a good idea.

(click image for source)

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2009 animal rabies statistics have recently been published in the Journal of the American Veterinary Medical Association (Blanton et al 2010). Here are some highlights:

• 6690 rabid animals were identified, along with four human cases. (One of those human cases was associated with travel to India, as described as described in a recent post).
• Rabid animals were identified in 49 states and Puerto Rico.
• 92% of infected animals were wildlife. Raccoons were the winners (actually, the losers, I guess) with 2327 cases, followed by 1625 bats, 1602 skunks, 504 foxes, 300 cats, 81 dogs and 74 cattle.

It is important to remember that these are rabies diagnoses, not all rabies cases. Certainly, more animals died of rabies and were not tested. These numbers may represent the "tip of the iceberg," particularly for some wildlife species. This can impact on the accuracy of the relative numbers between species, and year-to-year changes in cases, but doesn’t change the fact that rabies is present, widespread, relatively common and can infect a wide range of animal species, including pets. It also highlights why vaccination of pets is still important.

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A recent edition of Morbidity and Mortality Weekly Reports described a case of travel-associated rabies in a Virginia man. The man was diagnosed with rabies in October 2009. Treatment with the “Milwaukee protocol” (a rabies treatment protocol that resulted in survival of a single patient with rabies but which has not had much success since then) was instituted, however the man died after 25 days in hospital. Thirty-two people who had had close contact with him received post-exposure treatment.

According to his family, the man had an "encounter" with a dog three months earlier in India. The nature of the encounter was not known, and family members didn’t know whether he had received rabies post-exposure prophylaxis. (Considering post-exposure prophylaxis is pretty much 100% effective, I think it’s safe to assume that he didn’t). The rabies virus variant that was isolated was consistent with the strain found in dogs in India, providing more support to the suspicion that the infection was associated with this incident.

Travel-associated rabies is an important problem. This is the 7th case of rabies (and 7th death) in the United States acquired abroad since 2000. While rabies is rare in the US (and many other developed countries) it still kills tens of thousands of people each year, most of whom are infected by dogs. Rabies is endemic in dogs in many regions, including India.

People who are traveling need to be aware of the infectious disease risks in their intended destinations, be it yellow fever, malaria, rabies or others, and take appropriate precautions. Rabies vaccination is not indicated for travelers unless they are going to be working with wildlife or feral animals. The key for travelers is to understand that rabies exposure is a risk, that they must avoid contact with stray animals, and what to do if they are bitten. Access to rabies post-exposure prophylaxis may be limited in some regions, and people who are bitten by a suspicious animal may need to travel home to get proper treatment.

Rabies exposure is considered a medical urgency, but not an emergency, meaning you usually don’t need to sprint to the airport and get treated within a few hours. Rather, it means get to a physician as soon as possible - so don’t continue the rest of your vacation and then head to a physician a week or two later. The more severe the bite and the closer to the head that the bite occurs, the shorter the incubation period might be, so there are some situations where "urgency" and "emergency" are hard to differentiate, but the key is to be aware and get proper care as soon as is reasonably possible.

Image source: Humane Society of the United States (HSUS) (click for source)

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The Public Health Agency of Canada (PHAC) has issued a public advisory regarding salmonellosis linked to frozen rodents used as pet (reptile) food. The rather vaguely-worded advisory states that there have been seven reported cases of Salmonella caused by a specific strain that has been linked to frozen rodents. No details about the cases or the origin of the rodents are provided, however it presumably involves the large international Salmonella outbreak associated with Mice Direct, a mail-order rodent company. The advisory reminds people to take basic precautions when handling rodents that are used for reptile food.

Basically, the key is to consider all such frozen rodents biohazardous, and handle them accordingly. Remember to:

• Limit contact with the rodents as much as possible.
• Thaw them in a sealed container, preventing any contact with human food.
• Keep them away from kitchen countertops and other food handling surfaces.
• Wash your hands thoroughly after handling them.

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To me, a good general rule is "avoid buying things that are offered for sale at discount prices by a guy in a parking lot." Unfortunately, many people can't seem to pass up a "bargain" and can end up paying more in the end.

A good case in point is a man who was offering rabies vaccination of pets in retail parking lots in southern Oklahoma. James Allen advertised his vaccination "business" on Craig's List and set up shop in various parking lots. He also signed vaccine certificates and listed himself as a veterinary technician. (One problem is that veterinary technicians aren't allowed to sign rabies certificates. Another is that he is not one).  Mr. Allen has yet to be apprehended.

Mr. Allen is suspected of vaccinating hundred of pets with what is, at least from a regulatory standpoint, worthless vaccine. Since the vaccine wasn't administered by a veterinarian, all of those animals are considered unvaccinated. Therefore, if they are exposed to rabies, they face the prospect of euthanasia or a strict six-month quarantine.

Rabies vaccine must be given by a veterinarian in order for government authorities to consider an animal vaccinated in most regions. Mandating that rabies vaccine be administered by a veterinarian isn't a money-grab or veterinarians protecting their turf - it's a government regulation aimed at protecting pets and the public. Restricting rabies vaccination to veterinarians helps ensure that only proper vaccine is used, that the vaccine has been properly handled and administered, and that vaccination is adequately documented. In the absence of clear proof that an animal was properly vaccinated, it has to be considered unvaccinated, because you must err on the side of caution with a deadly disease like rabies.

It's pretty sad that it's so easy to get rabies vaccine in Oklahoma. It should only be available for purchase by veterinarians, but it's apparently easy to obtain from farm and ranch stores. Apparently, stores in Oklahoma can sell the vaccine but are supposed to post a notice saying animals are not  considered vaccinated if it's used. Why you'd allow a store to sell the vaccine when you don't recognize it as effective is beyond me, but that's what's happening.

(click image for source)

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The world is certainly getting "smaller," especially in terms of infectious diseases.  One example is the renewed controversy this month over the existence of Lyme disease in Australia.  A Sydney man was recently diagnosed with the disease following his death, and now a doctor from Laurieton claims to have "absolute proof" of at least two other Australians with the infection.

Lyme disease is caused by infection with one of three species of Borrelia, previously all known as Borrelia burgdorferi.  The disease is transmitted by a few specific species of ticks belonging to the genus Ixodes.  It is relatively common in areas of North America (including some parts of Canada) and Europe where these tick species are also found.  Ticks become infected by feeding on reservoir hosts, which are typically small mammals.  Early signs and symptoms in people following a bite from an infected tick can include a rash, fever, headaches, tiredness and joint pain.  The disease can be very difficult to diagnose because the initial signs are quite non-specific, particularly if the person does not report being bitten by a tick.

None of the tick species known to transmit Lyme disease are found in Australia, although there is one species of Ixodes tick there which some believe is a potential candidate for a vector.  However, after testing some 12 000 of these ticks, evidence of Borrelia infection has still not been found.  Also, none of the known reservoir hosts of Borrelia are said to live in Australia, and no other hosts have been identified.

The Laurieton physician, Dr, Mayne, claims he has "absolute proof" of Lyme disease in at least two of his patients, and says he has about 30 more patients with the disease as well.  "Proof" is a very strong word.  Not only is the disease hard to diagnose clinically, but there is also no perfect test that can detect infection for certain.  Even the DNA test on which Dr. Mayne is hanging his hat can be prone to false-negative and false-positive results.  The article also does not state whether or not the infected patients traveled outside the country and could have potentially picked up the disease in a Lyme-endemic area.  Further investigation is needed before anyone can claim to have "proof."

So why am I writing about this situation on a zoonotic disease blog, when there hasn't even been any mention of pets, and the disease can't be directly transmitted between people and animals anyway?  Because this is a perfect example of a situation in which physicians and veterinarians could potentially work together for the greater good, under the "one health, one medicine" banner.  Dogs in particular can also be affected by Lyme disease.  If the Australians really want to know if Lyme disease has made it to their shores - or perhaps some other tick-borne disease that mimics Lyme - then they shouldn't just be looking in people.  By alerting veterinarians that Lyme disease or a similar condition is cropping up in humans, they can start to look for it in the animal population as well.  If they're left unaware, Australian veterinarians may not consider Borrelia as a potential cause of illness in their patients and therefore not test for it.  If pets also start testing positive for Lyme disease, then hopefully that would be communicated back to the human medical community to increase testing of suspect cases there as well.  If more cases are identified, either human or animal, then further efforts could be taken to identify the tick source and reservoir hosts in Australia.

More information about Lyme disease and ticks in dogs is available in the Worms & Germs archives.

Image: The "classic" bulls-eye rash associated with a tick bite transmitting Lyme disease (source: CDC Public Health Image Library #9874)

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The other night, my daughter woke up yelling that she was "scratchy." She was quite upset and it continued for a while, despite my best attempts to calm her down. She had a bit of a fever and shortly after broke out in a good case of hives all over her body.

How is this relevant to this blog? Well, earlier that day, she was at the doctor's for her 3-year checkup. She wasn't vaccinated, but Heather made the observation that had she been vaccinated at that appointment, we would have wondered whether this was a vaccine reaction.

Determining whether something is a vaccine reaction can be tough. Too often, people blame a wide range of abnormalities on vaccination, without realizing that they occur at other times too.

The post I wrote a couple of days ago about rabies vaccination mentioned people not vaccinating their horses because of fear of vaccine reactions. I think it's fair to say that there are many more people that think their horse has a problem with vaccines than there are horses that truly have vaccine reactions. Sometimes, people are looking for an excuse not to vaccinate. Often, however, they are really convinced that a vaccine reaction occurred, even though the evidence may be weak.

A good example of this is West Nile virus vaccination. When West Nile virus vaccine first became available, there were rumours that it caused stillborn and deformed foals. There were internet sites reporting cases and publishing pictures of aborted fetuses. However, just because a mare was vaccinated and later aborts, that does not mean that the vaccine caused the problem. Lots of mares that aren't vaccinated have problems. That's why we do research - to see if problems like that are more common in vaccinated horses versus unvaccinated horses. Despite the internet paranoia, there is no evidence that West Nile virus vaccination produces dead or deformed foals, and fortunately this rumour seems to have died down. (I have to wonder how many horses died from West Nile because they weren't vaccinated as a result of this rumour. When some people stopped vaccinating children for measles because of false concerns about autism, there were tremendous increases in measles cases in many areas.)

Vaccine reactions can and do happen. There's no disputing that. Most are mild but some can be severe. However, lots of animals can develop identical-looking of problems at any given time. Just because they were vaccinated recently does not mean that the vaccine caused the problem. A vaccine reaction should be considered when abnormalities develop around the time of vaccination, but automatically blaming the vaccine must be avoided.

Some things to consider:

• Has the horse had this specific vaccine before? A reaction is probably less likely if the horse has had this specific vaccine multiple times in the past with no problems.
• Is the problem something that is typically observed with a vaccine reaction? Development of hives after vaccination is pretty suggestive, although it's not definitive. Other problems may be hard to link to vaccination.
• Was a single or combination vaccine used, or were multiple vaccines given at the same time? If a combination vaccine was used and the potential reaction wasn't severe, giving the specific components of the vaccine individually next time might help determine if it is a vaccine reaction and which component caused the reaction. There's no use stopping all vaccinations if the horse might only be reacting to one specific component. Sometimes, avoiding combinations is all that is needed (although whether that's because it decreases the risk of reactions or whether there wasn't actually a vaccine reaction in the first place is debatable). If there is a problem with one component, then that single component can potentially be skipped but the other vaccines still given.
• Was it a severe reaction? If not, then not having the vaccine may be a bigger risk than vaccinating. It depends on the disease and the risk of exposure. Also, pre-treatment of the horse with an anti-inflammatory may be enough to prevent a mild reaction or decrease the severity of a more significant reaction.
• Are there some horses that have severe reactions and can't be vaccinated safely? Yes, but there are very few. Vaccination decisions need to take into account the cost-benefit, in terms of protection and adverse effects. Sometimes, the risks are greater with vaccination, but usually they are not. If you think your horse has a problem with vaccines, work with your veterinarian to determine the best approach. Don't let a knee-jerk reaction automatically prevent you from vaccinating.

Image: A horse with hives along its neck (click image for source)

This Worms & Germs blog entry was originally posted on equIDblog on 16-Sep-10.

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The recent Salmonella recalls and raw food debate have led to a lot of discussion about Salmonella in pets, and also some confusion about what some different terms mean.

Salmonella vs salmonellosis

• Salmonella is the bacterium.
• Salmonellosis is disease caused by infection with the Salmonella bacterium.

When an animal is exposed to the Salmonella bacterium from food or feces, a variety of states can develop.

• No Salmonella, no disease: In these cases, Salmonella does not survive passage through the intestinal tract and nothing happens. The animal doesn't get sick and Salmonella is not detectable.
• Colonization (also called "carriage"): This is when Salmonella survives passage through the stomach and grows, at least for a while, in the intestinal tract, but does not cause disease. Colonized animals may shed Salmonella, meaning they pass the Salmonella bacterium in their feces, and may therefore be a source of infection for people or other animals. Colonized animals will most often eliminate Salmonella on their own in a short period of time (days to a couple of weeks) and usually don't get sick. It is possible, however, that a colonized animal could develop salmonellosis from Salmonella living in its intestinal tract. This is most likely to occur if something allows the bacterium to overgrow in the intestinal tract or reach the bloodstream, which is most likely in young, old or sick animals.
• Transient passage: This occurs when live Salmonella that have been ingested survive passage all the way through the intestinal tract, but without the bacterium becoming established in the body and without disease. Salmonella can be detected in feces. It's hard to distinguish transient passage from short-term colonization, and it's not clear whether transient passage really occurs.
• Enteric salmonellosis: This is the most common form of disease, characterized by diarrhea and potentially varying degrees of depression, weakness, lethargy, decreased appetite and vomiting.
• Systemic salmonellosis: This uncommon and severe form of disease occurs when Salmonella enters the bloodstream (by invading through the intestinal wall) and causes a bloodstream infection and/or infection of other body sites/organs. This form is often fatal. It is most common in young and old animals, or animals with other diseases that affect their ability to fight infections.
• Contamination: It is also possible for animals to spread Salmonella that has only contaminated the outside of their bodies. For example, a dog eating contaminated food might get Salmonella on its face. The bacterium doesn't make in to the intestinal tract and can't cause colonization or disease in the dog, but the dog's face could be a source of infection for other individuals for a short period of time, until the bacteria die or are physically removed.

Image: Salmonella sp. on an XLD agar culture plate 24 hours after innoculation. (Source: CDC Public Health Image Library #6619)

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Israel has experienced a major upswing in canine rabies cases since 2009. There had been a significant decline since 2003, when oral rabies vaccination of foxes was started, but the recent increase has been in dogs and jackals, not foxes. Now, stray jackals and dogs are the main rabies vectors in northeastern Israel, the area affected by the current outbreak.

Stray dogs are a significant concern in terms of rabies because they can have close contact with humans and wildlife. Dogs are the most common source of human rabies internationally and thousands of people die each year from rabies acquired from dogs.

The increase in rabies in stray dogs and jackals has lead to discussions about how to control the stray population and reduce the risk of rabies. Previously, it was common for authorities to shoot strays in parks and nature reserves. This practice was stopped a while ago, however the Israel Nature and Parks Authority has now asked for permission to shoot strays in the interest of rabies control. The proposed regulations would allow strays to be shot in national parks, reserves, and "any other open area where wildlife species are considered at risk", but not unless their presence poses "an immediate discernible risk to wildlife and never within 1 km of human habitation."

This seems to be a wildlife protection program disguised as a rabies control program. The emphasis is on protection of wildlife, since packs of stray dogs have had major impacts on some endangered wildlife (e.g. fallow deer). It's not really a good rabies control program, since culling alone is unlikely to be effective, and only culling when the dogs pose a risk to wildlife and away from human habitation presumably would only have a limited impact on the prevention of human rabies. If they want to control the dog population to protect endangered species, they should just say that. If they want to control rabies, they need a comprehensive rabies control program that involves consideration of various approaches such as vaccination of strays and jackals, sterilization of strays, public education to decrease the risk of exposure, and vaccination of domestic animals. A cull alone won't cut it for rabies control.

Photo: A pair of Golden Jackals (Canis aureus) in Israel (photo credit: Michael Baranovsky)(click for source)

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A field worker from Mexico died in Louisiana this weekend from rabies. This is the first case of human rabies in Louisiana in over 60 years, but based on the time the man had been in the country and the incubation period of rabies, it is believed that he was infected in Mexico. Human-to-human transmission of rabies is rare, but healthcare workers and other people he had recent contact with are being evaluated to determine if post-exposure treatment is required.  In the case of the man's co-workers, they could have also been exposed to the same source of rabies that infected him.

The original source of infection isn't known, or at least has not been reported. Wildlife are the main source of rabies exposure for people in the US, but dogs are the most common source of human infection internationally. Dog-associated rabies cases in people from Mexico have been previously reported in the US, and it's certainly possible here.

(click image for source)

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Yet again, a large number of people are undergoing rabies post-exposure treatment because they were exposed to a rabid raccoon that was "adopted" from the wild. In this case, a North Carolina family found a baby raccoon at the side of the road and decided to bring it home. Over the next couple of weeks, various family and friends handled the raccoon, and many were bitten or scratched in the process. The raccoon then died and was identified as being rabid. Forty-five people are now being assessed to determine whether they need to be treated for rabies exposure.

The family dog, which was unvaccinated, has been taken by Animal Control and now faces either a six-month strict quarantine or euthanasia. I suspect the dog will be euthanized.

So, this probably well-meaning but misguided action has resulted in:

• the need for costly post-exposure treatment of many people
• presumably a stressful period for many of those people
• probably the death of the pet dog (although not having the dog vaccinated played a big role here too, since if it was vaccinated, it would only face a 45 day observation period at home, not a strict six-month quarantine or euthanasia).

Fortunately, the raccoon was tested. Otherwise we might be talking about human deaths from rabies, instead of people needing post-exposure treatment. The people who took in the raccoon could also face charges since keeping wildlife without a permit is illegal, but it sounds like that's unlikely to occur.

A few take-home messages from a situation like this:

• Leave wildlife in the wild.
• Vaccinate your pets.
• If you are exposed to an animal that is acting strangely, make sure it's tested for rabies (they did this right, at least).

(click image for source)

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A couple questions that I received about C. difficile and hospital visitation dogs:

Is there any concern about cross contamination from dogs/handlers that visit health facilities and get contaminated by C. difficile? I see on this site a concern about dogs being contaminated by visitation and I wonder if the Delta Society has considered this to be an acceptable risk.

Dogs (and handlers) could be sources of C. difficile in hospitals. We have shown clearly that dogs that visit hospitals are at increased risk of shedding C. difficile in their feces, presumably because they ingest C. difficile spores from the hospital environment and/or patients' hands. All dogs that go into hospitals are at risk, with dogs that lick patients and that are allowed up on beds at increased risk (Lefebvre et al 2009). We have also shown that the dog's body can become contaminated with C. difficile after visiting a hospital.

Should there be a period of time mandated between visits to account for possible contamination?

That's hard to say, but probably not. Contamination is a potential problem and certainly occurs, but we don't know how long it lasts nor whether providing a "rest" period actually does anything. Clostridium difficile spores, the form of the bacterium that would be present on a dog's coat, are very environmentally tolerant and can survive for years. Therefore, giving a few days break in between visitation would not result in the bacteria dying. However, some spores would presumably be physically removed over time, through shedding of hair, grooming and other activities. Based on that, it's plausible that the longer the time between visits, the less likelihood of contamination still being present. Whether this actually helps, we don't know.

What to do?

Among other things, we need to consider whether there is actually any evidence of risk. We don't know whether dogs are able to transmit C. difficile in hospitals. My assumption is that there is some degree of risk, but it's limited and can be controlled with good hygiene and the use of basic visitation practices, as highlighted in the "Guidelines for animal-assisted interventions in healthcare facilities" (American Journal of Infection Control, 2008).

Another thing to consider is whether there are any measures that can be taken to reduce potential risks, while maintaining a practical and effective visitation program. A key component of this is knowing that there are factors that make it more likely that a dog will be exposed to C. difficile during visitation. If a specific subset of dogs is at increased risk, then you have a clearer way to approach it. In this case, dogs that are allowed to lick patients and that are allowed on beds are at increased risk. These activities are modifiable - you can prohibit them without having a significant impact on the visits. Licking can be prohibited. Dogs can be kept off beds unless it is required, and when that's the case, they can be placed on a towel or some other barrier to reduce their exposure to C. difficile from the bed. Additionally, we know that if a dog is being treated with antibiotics, it's more likely to shed C. difficile, so dogs that are being (or have recently been) treated with antibiotics should be excluded from visitation.

For C. difficile to be a problem, it has to go from human or animal feces to a patient's hands and then to a patient's mouth. There are multiple potential interventions to interrupt this chain of transmission. At the end of the day, however, hand hygiene is the key. If people wash their hands before and after touching the dog, there should be much lower risk of disease transmission. A problem is that when I say "hand washing," I mean hand washing - not use of an alcohol-based hand sanitizer. Clostridium difficile spores are resistant to alcohol. That creates a conundrum because the use of alcohol hand sanitizers, a common and recommended hand hygiene method, doesn't have the ability to kill C. difficile. Since not all visitation patients are able to get up and go to a sink, that complicates C. difficile control.

(click image for source)

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An article released today in the journal Pediatrics (Behravesh et al, 2010) provides more information about a salmonellosis outbreak linked to pet food. The outbreak itself is old news - I commented about it almost two years ago. What is new is the detailed epidemiological analysis of the outbreak, and there is some interesting information in the paper that is worth reporting. Here are the highlights:

Almost 50% of people who were infected were kids two years of age or younger.

• That's not too surprising considering kids less than five years of age are a high-risk group for getting sick after being exposed to Salmonella.

Households with sick people were almost 7 times as likely to have recently purchased the affected food.

• This provides good evidence of the link between the contaminated food and disease.

The Salmonella strain that was found in people was also found in bags of pet food at the manufacturing plant, samples from the manufacturing plant environment, and fecal samples from dogs that had eaten the food.

• This is pretty convincing evidence that the food was the source. Because they were able to type the Salmonella strain in people and it was an uncommon strain, and they then found the same uncommon strain in food, animals and people, it paints a pretty clear picture of what happened.

Illnesses occurred over a 3 year period.

• This is pretty concerning. This was more than a little lapse at a plant that led to contamination of a single batch of food or a short term event. This was a major failure in quality control that was undetected for a long period of time, resulting in at least 79 human infections in 21 US states.

A cluster of infections caused by the strain involved here, S. Schwarzengrund, was identified early in the outbreak. However, a link with pet food was not considered until the following year.

• That's unfortunate but maybe not surprising. There are a lot of other more likely sources of infection that were probably focused on initially. "What kind of pet food do you feed your dog?" was unlikely to be a routine question asked of people with infections. Identification of outbreaks caused by uncommon events is difficult and typically takes more time.

People that fed their dog in the kitchen were 4 times as likely to have an infection.

• Feeding a pet in the kitchen presumably increased the chance of cross-contamination with human food or contamination of the food preparation environment.

The cause of contamination was never identified. The authors of the paper suspected that contamination occurred after extrusion (the process during which the kibble is formed), which makes the most sense. The extrusion process results in high enough temperatures to kill bacteria like Salmonella. Possible causes of contamination include contaminated equipment used after extrusion, cross-contamination of pre- and post-extrusion food and contamination of substances (e.g. flavour enhancers) sprayed on kibble after extrusion. The fact that Salmonella was found in the room where materials were sprayed on the kibble supports this further.

In general, dry pet food is quite low-risk in terms of Salmonella contamination, but just like with other non-raw-animal products such as lettuce, tomatoes and sprouts, contamination can occur and human infections can result. The best way to reduce the risk is to use good general hygiene practices, particularly washing hands after handling food, keeping pet food and pet food bowls out of kitchens and limiting contact of young children and other high-risk individuals with pet foods.

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How likely is E. cuniculi to be trasmitted from an infected rabbit to a dog? My sister has a positive rabbit and my dog was just diagnosed with kidney insufficiency.  Now that the dog's kidneys are compromised, should we be concerned?

Encephalitozoon cuniculi is a strange little organism that is now classified as a fungus, but is also similar to some types of protozoal parasites. It is an important (and often overlooked but potentially treatable) cause of neurological disease in rabbits. It is quite common in healthy pet rabbits, and infected rabbits shed the organism mainly in urine.

Less is known about E. cuniculi in dogs. Neurological disease, stunted growth and renal failure are the most common problems that develop. Disease usually occurs in young dogs (less than 1 year of age, with most cases in dogs a couple of months old or younger). Some studies have reported antibodies against the organism in a large percentage of healthy dogs, indicating that they've been exposed at some point, but most studies have found antibodies in few or no dogs.

The risk of transmission from rabbits to dogs is not known. There are a few different types of E. cuniculi, including one type (type I) that is called the "rabbit strain" and another (type III) that is called the "dog strain." The ability of the rabbit strain to infect dogs, particularly dogs with normal immune function, is unclear. Considering the low incidence of infection in dogs (especially older dogs), the different types of E. cuniculi that predominate in dogs and rabbits, and the commonness of kidney disease in dogs, I doubt there's a link between the rabbit's infection and the dog's kidney disease in this case.

(click image for source)

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Recent Salmonella recalls have led to some questions about the best way to diagnose salmonellosis in dogs and cats.

The first issue is when to test. In general, there is no indication to test healthy animals. Testing should be reserved for animals with diarrhea or other signs of salmonellosis (e.g. fever).

When testing is indicated, a few things should be considered:

The Sample

• A fresh sample is best. It should be submitted for testing as soon as possible, but it can be kept cool (i.e. refrigeration temperature) for a day or more if it can't be submitted right away.  (Do NOT keep a fecal sample in your fridge at home! Take it to your local vet clinic and they will keep it in a designated specimen fridge.)
• More is better. A reasonable volume of stool (e.g. a tablespoon or two) is preferred to something like a rectal swab. Testing can be performed on rectal swabs but they are lower yield because they contain a lot less stool.  See image right: standard-size 30 mL fecal sample containers (click for source).

The Test

There are two tests used to detect Salmonella in feces: culture and PCR.

Culture is used to grow and isolate the Salmonella bacterium. Usually, enrichment culture is used, whereby the sample is first cultured in a selective broth culture medium, then put on culture plates. This increases the recovery rate but takes more time.

Advantages of culture are:

• A positive is definitive - the bacterium is definitely there and alive.
• An isolate is available for subsequent testing such as determining the susceptibility to antibiotics and typing it to see what strain is involved.

Disadvantages of culture:

• Salmonella can be hard to grow for labs that don't have a lot of experience and good protocols.
• A few days are required to obtain results, particularly if proper enrichment methods are used.

PCR (polymerase chain reaction) is a molecular diagnostic test that looks for DNA from a particular organism (in this case, Salmonella).

Advantages of PCR:

• Speed. Results may be available within 24 hours.

Disadvantages of PCR:

• Tests validated for dogs and cats are not usually available.
• The test detects both live and dead bacteria, so a positive result could theoretically be from ingestion of dead (and therefore irrelevant) bacteria.
• False negative results can occur from low levels of Salmonella or substances in the stool sample that inhibit the test.
• Lab quality control is critical but not always good.

Current recommendations are to base diagnosis on culture. PCR can be used as a faster presumptive test, but culture should be performed to confirm the diagnosis and get a bacterial isolate that can be further tested for antibiotic sensitivity and typed to see what strain is involved.

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Following on the heels of a limited recall of feline dry renal diets because of potential contamination with Salmonella, Proctor and Gamble has now recalled all Iams Veterinary Dry Products, as well as Eukanuba Naturally Wild, Eukanuba Pure and Eukanuba Custom Care Sensitive Skin. These products are sold across the US and Canada, and all products with best-before dates between July 1, 2010 and Dec 1, 2010 (so, presumably everything that is on the market at the moment) are included. The broad scope of the recall is apparently a proactive measure based on the premise that since Salmonella was found in some products made at a particular production facility, there is the potential for contamination of everything made there. More data about what they have found and how widespread the contamination is would be nice (but is not forthcoming at the moment).

No illnesses have been reported. If your pet is being fed one of the recalled diets and develops diarrhea, vomiting or other signs of illness (e.g. weakness, fever, decreased appetite), it is important to consider the possibility of Salmonella. Similarly, if any people in the house develop these types of symptoms, they should make sure their physician knows they may have been exposed to Salmonella. Presumably, the level of contamination was low and the risks to the general public (human and canine/feline) are relatively low, with higher risks to people and animals with compromised immune systems or other diseases that limit their ability to fight off a bug like Salmonella.

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Proctor and Gamble has announced a recall of two lots of Iams' Veterinary Formulas Feline Renal, a prescription dry cat food. The lot numbers are 01384174B4 and 01384174B2. Anyone that has this food should stop using it immediately. Since these are prescription diets that should only be available through a veterinarian, affected customers should presumably contact their veterinarian for information about a replacement or refund. If a cat that has eaten this food develops diarrhea, Salmonella should be considered as a possible cause and a stool sample should be tested.

As with most of these recalls, no illnesses have been reported, although lack of reported cases doesn't necessarily mean lack of cases. While Salmonella contamination of dry pet food diets is quite uncommon, it can happen.  It's a good reason for people to make sure they wash their hands after having contact with any pet food or the pet's food bowl, and to make sure that pet food is kept separate from food meant for human consumption.

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I get this question surprisingly often. In one way, that's good because it shows increasing awareness of the potential for interspecies transmission of microorganisms. In some situations, when a person has an infection, the pet should be considered in case it was the source of the infection and/or in case it's at risk of becoming infected by the person.

Clostridium difficile is a very important cause of diarrhea (and sometimes more severe intestinal disease) in people. Previously it usually only affected people confined to hospitals and people being treated with antibiotics, but it's now being identified more often in people in the community.

The potential for interspecies transmission of this bacterium is real.

• C. difficile can be found in a small percentage of healthy dogs and cats.
• The strains of C. difficile in dogs and cats are almost always the same as those found in people. My lab has one of the largest collections of C. difficile around and we only have a couple of C. difficile isolates from dogs and cats that we have not found in people.
• Dogs that visit human hospitals are at increased risk of shedding this bacterium in their stool, and certain types of contact with people have been identified as increasing this risk (Lefebvre et al 2009).
• Dogs owned by an immunocompromised person are at increased risk of shedding C. difficile (Weese et al 2010), presumably because the person is more likely to shed the bacterium and subsequently infect the pet.
• Dogs that are owned by people being treated with antibiotics are more likely to shed the bacterium (Lefebvre et al 2009). That's probably because, as with immunocompromised people, when someone's being treated with antibiotics, they have a greater likelihood of shedding C. difficile and their dog subsequently becomes infected.

However, there's currently no indication that testing is needed.

• What would the results tell you? If you identify C. difficile in your dog and you have a C. difficile infection, does that mean that you were infected by the dog, you infected the dog or you were both infected by the same source?
• What would you do with the results? There's no indication to treat the dog if it's positive and healthy.
• What testing would you actually get done? Testing for diagnosis of C. difficile disease usually involves trying to detect bacterial toxins in stool. The tests aren't meant to be used on normal stool. To really know what's going on, you'd need to have the bacterium cultured from your pet's stool as well. Not many labs can do that. Furthermore, to get really useful information, you'd also need to get your stool cultured and, if C. difficile was present in both you and your dog, molecular typing would be required to show that they were the same strain. Very few places can do that. Even with that information, at the end of the day, finding the same strain in you and your pet doesn't tell you more than the fact that the bug probably moved between you and your pet, in one direction or another.

If you have C. difficile, it's reasonable to take precautions to reduce the risk of infecting other individuals, both human and animal:

• Practice good hygiene. Wash your hands thoroughly after using the washroom.
• Don't let your dog drink out of the toilet.
• Use antibiotics judiciously. If your pet is being treated with antibiotics and you have C. difficile, there's probably a greater chance of your pet picking up the bacterium.
• If you have C. difficile and your pet develops diarrhea, tell your veterinarian. It's important that they know that your pet may be at higher risk of C. difficile infection.

If you have recurrent C. difficile infections, considering the pet as a possible source might be reasonable, but we don't currently know what role pets may play. As described above, investigating your pet as a possible source would require culturing stool from both you and your pet, having both typed using molecular tests, and a joint effort involving your veterinarian and physician.

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Trap/neuter/release (TNR) programs involve trapping feral (stray) cats, then spaying or neutering and vaccinating them. Some cats are adopted, while the majority are released. The goal is to reduce the feral cat population by limiting the number of breeding animals, and to increase overall vaccine coverage in order to reduce illness and deaths. One such TNR program has come under fire in a Texas town.

In Leander, Texas, trapping wild animals (including feral cats) is illegal, but authorities have ignored the rules for groups that run TNR programs. One citizen, Carmen Amaya, is leading a charge to get authorities to start enforcing this so that TNR programs can't happen. The main reason appears to be that she's upset her dog was scratched by a feral cat and ended up with $800 in vet bills (not something I'd be happy with either, but is this really the best way to direct her anger?).

A non-profit group, Shadow Cats, has led the TNR effort and has trapped, neutered and vaccinated  about 3000 cats in Central Texas since 2004. About 500 were adopted and the rest released. The organization knows they are working outside the law and have lobbied for it to be changed. That was being considered in June, but opposition from Amaya and others has led to the creation of a task force to make a recommendation, which is due next month. In the meantime, Shadow Cats has ceased activities in Leander.

I'm not sure what the opponents to TNR really want. If it's just cessation of the program, there's no benefit to them.  Without the program:

• Stray cats will continue to be around, and there will probably be more of them.
• Potentially adoptable cats won't be taken into homes to improve the lives of those cats.
• Vaccine coverage of the population will decrease. That's a critical point, because it will result in lower "herd immunity."   With herd immunity, the greater the percentage of a population that is immune to a disease (i.e. vaccinated), the lower the likelihood of the disease establishing itself in and spreading through the population, even among those individuals who don't get vaccinated.

On the other hand, if these people simply want Shadow Cats to stop releasing the neutered cats back into the neighbourhood, it means either 1) finding a way to care for all those cats in shelter, which simply isn't realistic for a multitude of reasons, not the least of which is cost, 2) releasing the cats elsewhere, which doesn't actually solve the problem, it just makes it someone else's, or 3) euthanizing all the cats instead of neutering and releasing them.  If they're hoping that by objecting to the TNR program that all the cats being trapped will be euthanized instead, they need to realize:

• It's not going to happen as long as volunteer "rescue" groups are in charge of the program. These groups aren't going to trap and kill.
• The city is unlikely to do it either, and there's a cost to having city personnel catch the cats and take them somewhere to be euthanized.
• Most importantly, culling has been shown time and time again to be an ineffective way to control feral animal populations. What's needed is a combined approach that includes measures such as neutering and vaccination, education to reduce the risk of human and domestic animal exposure to feral animals, and taking steps to discourage feral animals from spending time in close proximity to people and domestic animals.

Amaya states that "her" feral cat is a nuisance and she doesn't want it on her property. So what is she trying to accomplish? If anything, her actions will just help her single stray cat turn into a large extended family of stray cats that are susceptible to rabies.

There are certainly concerns with feral cats and TNR programs. They are not perfect and not always run well. Some people are opposed to them for various reasons, some of which are quite reasonable. It's a tough issue because one person's idea of success might be completely different from someone else's. Some people focus on the number of animals, while others focus on the quality of life of the animals, public health aspects, impacts of feral cats on wild bird populations and other diverse areas. A local council isn't going to be able to solve these problems, and it really comes down to an assessment of the potential usefulness of the program and the ability of the people involved to do it safely, ethically and legally.

Personally, I'd rather see well-designed, well-run and regularly-evaluated programs to try to reduce feral cat (and dog) populations, and (perhaps more importantly) increased vaccination coverage in the feral animal population, than nothing. Feral animals aren't going to disappear if we ignore them.

Image source: www.shadowcats.net

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Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is becoming a huge problem in dogs (and to a lesser degree cats). I think it can easily be called an epidemic, and probably even a pandemic, considering the degree of spread, the massive increase in cases and the international distribution of this multidrug-resistant bacterium.

Public health concerns regarding MRSP have received attention because of the huge problem with MRSA (methicillin-resistant Staphylococcus aureus) in people. My line with S. pseudintermedius in general is that while there are only periodic reports of infections in people, exposure to this bacterium is very common, since it is carried by a large percentage of healthy dogs. Given the frequent exposure and very small number of infections, it’s not a particularly pathogenic bacterium for people. The same should apply for MRSP, since methicillin resistance doesn’t’ make it inherently any more able to cause disease, it just makes it harder to treat. However, I always add the statement that, while the risk is pretty low, I’d rather not have an infection with a highly drug resistant bacterium, so we need to pay attention and try to reduce the risk of transmission.

A paper in an upcoming edition of the Journal of Antimicrobial Chemotherapy (Stegmann et al 2010) shows that these concerns are not unfounded. This report, from Switzerland, described an MRSP infection in a person that developed after sinus surgery. The bacterial strain that was involved was sequence type 71 (ST71), the predominant strain found in dogs in Europe. The affected person had a dog with various health problems, but unfortunately the dog was euthanized (presumably not because of the person’s infection) before samples could be taken to see if it carried the same strain. Since we know that S. pseudintermedius can move between pets and their owners (although usually without causing any problems), it's reasonable to assume that the dog was the source of infection here.

More information about MRSP and MRSA can be found on the Worms & Germs Resources page.

(click image for source)

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Infection control is a constantly evolving and expanding area - for the good. Paying close attention to infection control in human hospitals is a relatively recent phenomenon, and the advances in infection control are now having an impact outside of hospitals. Pandemic H1N1 influenza drove a lot of changes, but there's been a general increase in awareness of the need for routine infection control in the greater community. This applies to veterinary clinics and living with animals, but is also evident in everything from protocols in workplaces to summer camps.

We're getting ready to send my oldest daughter to summer camp for 12 days. Back in my time, I doubt there was much of an infection control plan for summer camps. If anything, it was probably "don't puke on the other campers and try not to eat too much dirt."

Oh, how things have changed! Last night, we received an email from the camp reminding us to keep our daughter at home if she is sick and outlining their infection control program. Among the infection control measures are:

• Having 2 12-foot handwashing stations outside of the Dining Hall, with everyone required to wash their hands before eating
• Having sinks equipped with handwashing supplies present in all buildings
• Having hand sanitizers throughout the Dining Hall and in every cabin
• Training staff in infection control protocols
• Cleaning cabins every day, with daily inspections of cabins by their "Public Health Supervisors"
• Daily spraying down of surfaces like Dining Hall tables, door handles, toilet handles, taps etc. with disinfectant
• Screening of all kids by one of the Registered Nurses on the first day of camp

Pretty impressive effort, in my opinion. Like everything else, compliance is critical and having good facilities and plans doesn't guarantee good practices, but the efforts put into developing this program and communicating it suggest that they'll be paying attention to it. Even with a good program, camps are an excellent breeding ground for infectious diseases and are perpetually an outbreak waiting to happen, but a good infection control program should greatly reduce the risks.

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A study we just published in the journal Veterinary Record (Floras et al 2010) described an MRSA outbreak in a dog breeding kennel. That's a little unusual in itself, but considering how MRSA is spreading amongst the dog population, it's not really astounding. What was unique about this outbreak was the strain of MRSA that was involved, sequence type 398 (ST398).

ST398 MRSA is commonly referred to as livestock-associated MRSA, since this strain seems to have originated in pigs, and is commonly found in pigs and calves in some regions of the world. It can also infect people, and high rates of carriage of this MRSA strain can be found in pig farmers, pig vets and other people with close contact with livestock. In some areas of Europe, this strain is a big problem, accounting for a large percentage of human MRSA infections. Interestingly, it seems to be a rare cause of illness in people in North America (at least at the moment).

Dogs seem to be innocent bystanders when it comes to MRSA. The vast majority of MRSA strains found in dogs are common human strains, indicating that, ultimately, MRSA in dogs originated in people. There are only two other reports of dogs with ST398, both from Europe. One was a dog with a skin infection. The other was a healthy dog (a carrier) who was owned by a pig vet. 

This kennel outbreak involved a larger number of dogs, including both healthy carriers and sick dogs. Overall, MRSA was isolated on at least one occasion from 23/42 (55%) dogs in the kennel. In a couple of litters, most of the puppies were identified as carriers, but fortunately most stayed healthy. MRSA caused skin infection in one puppy and mastitis in a mother dog, and was also found in the respiratory tract of a puppy that died (although it may or may not have been the cause of death).

The source of the ST398 was not identified. One of the owners worked on a pig farm, but MRSA was not isolated from either owner. It's most likely that the owner did bring MRSA home from the farm, either as a transient carrier (in their nose) or as a contaminant on their skin. Regardless, once it got into the kennel, it was able to move between dogs, either from dog-dog contact or with the help of human hands. Fortunately, ST398 MRSA carriage by dogs seemed to be transient in this situation, which is consistent with what we know about carriage of other strains. MRSA is not really adapted for long-term survival in dogs, so they only carry it for short periods of time. That's a big advantage when it comes to trying to control this pathogen.

While we have to be careful to not over-interpret data from only a few studies, this report indicates that ST398 can cause disease in dogs and it can be present in apparently healthy dogs. It can also be spread relatively easily amongst dogs in a breeding kennel situation. While a pig-link was not confirmed, it's reasonable to suspect that dogs with contact with pigs (and perhaps other livestock) might be at higher risk of developing ST398 infections, as is the case with people.

This is a perfect example of the one medicine concept, and why we need to think about infectious diseases in broad terms, not just focusing on specific populations or species. This situation involved a pig Staphylococcus aureus that somehow acquired methicillin-resistance, spread widely around the world (most likely in pigs, initially), spread to people, and then likely spread to another species, in this case dogs.

(click image for source)

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All lots of "Pro-Pet Adult Daily Vitamins" have been recalled by United Pet Group, Inc. because of Salmonella contamination. At least one lot has tested positive for Salmonella, although there is no mention about whether the bacterium was detected during routine testing or in response to a problem. Regardless, Salmonella contamination of these products is a concern because of the potential for disease in dogs fed the vitamins. Further, people could become infected from contact with dogs that become infected from the vitamins, or from handling the vitamins directly. If you have these vitamins, stop using them immediately. If your pet has been receiving these vitamins and develops fever, diarrhea, anorexia or any other signs of illness, take your pet to your veterinarian and make sure he/she knows there has been a chance of Salmonella exposure.