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

Case reports of infections acquired from pets are sporadically found in the human medical literature. A common problem with these reports is the failure to look for true evidence of zoonotic transmission. The typical thought process is "We found this bug in a person, it's most often found in animals, so this person must have gotten it from their pet." Often, this likely is actually the case (although some evidence would be nice). In other instances, like the Pasteurella bone infection described in the Orthopedics paper I wrote about recently, this assumption is probably completely off-base.

Something that is usually missing from these reports is any investigation of the suspected pet. Finding the bacterium in question in/on the pet, and showing that it's the same strain as was found in the person goes a long way to supporting the conclusion that the pet was the source. It's not a 100% guarantee, since you can't say whether it went from pet-to-person or person-to-pet, but with a typically pet-associated bacterium its much more likely to have come from the pet, so finding the same strain in both pet and person is pretty solid evidence. Most case reports don't bother even trying to get this much information (but they still get published...).

A case report in an upcoming edition of Zoonoses and Public Health (Register et al 2012) is another example of a study that provides some information about a potential pet-associated infection, but stops short of the type of proof that is needed. To their credit, the pet wasn't available for testing and they are clear that it's a "possible" case of zoonotic transmission, which puts them a step up on other studies, but it's still too bad the additional information couldn't be reported.

The case report describes an 11-year-old girl with cystic fibrosis (CF). People with CF are at greatly increased risk of respiratory infections, including infections caused by microorganisms that typically don't cause disease in other people. This child had a sputum sample collected during a routine doctor's visit, when she didn't have any signs of respiratory infection. Bordetella bronchiseptica, a bacterium most often found in dogs and cats (and one of the causes of kennel cough (aka canine infectious respiratory disease syndrome) in dogs), was isolated from the sample. When this was explored further, it was revealed that child's family had obtained a new kitten three weeks earlier, and the kitten had signs of respiratory disease.

Unfortunately, the kitten had been removed from the household by the time B. bronchiseptica was diagnosed in the girl, so it couldn't be tested. (They don't say why the family got rid of the cat.) However, the authors at least took it a step further and did some detailed molecular characterization of the bacterial strain they recovered from the sputum sample. Different genetic traits suggested that the strain was feline in origin, and, combined with the fact that the child had contact with the kitten, this provided a little more support to the hypothesis that the cat was the source. It's not proof, but still interesting. They also determined that the B. bronchiseptica strain was missing a gene that's associated with helping cause disease, suggesting it's not as able to make people sick. That might explain why the child was carrying the strain in the absence of disease, although people can carry lots of different bacteria that can potentially cause disease without being clinically ill.

In the end, it was an interesting little report and the authors conclude with a couple of good statements:

"Acquisition of detailed clinical and epidemiological data paired with discriminatory genetic comparison of case isolates and contact isolates is needed to more firmly establish transmission patterns and identify likely contact risks." (A fancier way to say what I said above.)

"...it seems advisable to counsel CF patients regarding adherence to practices that minimize opportunities for zoonotic transmission of B. bronchiseptica from family pets or other potentially infected animals."

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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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New York City's Algonquin Hotel has a feline tradition of sorts - namely having a resident cat to greet people in the lobby. Matlida III is the tenth in a line of hotel cats that dates back to 1932.  She has her own page on the hotel's website, and her own email address. Yet the City's Department of Public Health has issues with the hotel having both Matilda and another tradition - food in the lobby - co-existing.

According to the hotel website, the cat normally has the run of the building except for the dinning room and kitchens.  However, since the hotel also serves food in its lobby, it's running afoul of the health code, which prohibits pets in any area where food is served. (Interestingly, the news article says there's an exception for restaurants that serve seafood. I'm not sure why, but I guess we all know cat's would never go for seafood...). Therefore, Matilda is now being kept on a leash and restricted to the reception desk, main entrance and coat room. 

So, does any of this make sense? There's no clear answer, and like a lot of other infectious disease issues, it comes down to cost/benefit. Every human/animal encounter comes with some risk of infectious disease transmission, as does every human/human encounter. Some things increase the risk, while others can decrease the risk.

Having food served around animals increases the risk of disease transmission, because many of the infections we're concerned about are transmitted by ingestion of bacteria and parasites from animals. Based on that, it seems like a reasonable rule, even though it's probably much more likely that someone would contract an infectious disease from a person in the lobby than from the cat. Ideally, they'd figure out a way to have the food in another area so the cat could still roam the lobby without having access to the food serving area itself, but that may not be an option for the hotel.

One thing that often gets overlooked in these discussions is allergies. In reality, allergies are probably the biggest human health issue with a situation like this. Some people are extremely allergic to cats and wouldn't expect to encounter a cat in a place like this. An unexpected cat encounter could cause significant discomfort for some allergic individuals. Letting the cat hang around the coat room raises similar concerns because of the potential for contamination of peoples' coats with fur and dander.

Issues like this tend to generate a polarized response, with some people outraged at the cat's restriction and others outraged at peoples' outrage, reasoning that a hotel lobby is no place for a cat.

Condolences can be sent to Matilda via her personal email address: matildaalgonquincat@algonquinhotel.com

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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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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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The latest edition of Emerging Infectious Diseases (Berger et al 2011) describes a case of Corynebacterium ulcerans infection in a women that was likely acquired from her cat.

Corynebacterium ulcerans is a bacterium that's related to C. diphtheriae, the cause of diphtheria. Some strains of C. ulcerans can produce toxins that cause diphtheria-like disease, and with the success of diphtheria vaccination, C. ulcerans is now the leading cause of diphtheria-like disease in people in some regions. Typically, C. ulcerans infections are associated with ingestion of contaminated milk or dairy products, but reports of infections acquired from dogs and cats appear to be on the rise. As is often the case, whether this is because it's becoming more common or that people are simply looking more is unclear.

In this report, a woman from Germany developed diphtheria-like disease, including a sore throat, ear ache, hoarseness and nasal obstruction. A swab was taken from her nose and throat, and toxigenic C. ulcerans was isolated. She didn't report any livestock contact and had not traveled abroad, so other possible sources of infection were considered, particularly other types of animal contact. She had a cat, so nose and throat swabs were collected from her pet, and the same strain of C. ulcerans was isolated.

With this type of investigation, you can't prove that the cat gave the bug to the owner. Since the cat was healthy and tested after the owner was sick, you can't say for sure whether the cat was the original source or if it was infected by the owner. However, with a bug like C. ulcerans that has been associated with pets before and that can be carried by healthy cats, the conclusion that it came from the cat is reasonable. The cat was treated with antibiotics and C. ulcerans was not detected after treatment.

This is an interesting report.  It's always good to see people thinking about the relationship between human and animal disease, but at the same time, it's important to put this into context. Yes, C. ulcerans is a potential zoonotic concern, but it's rare. Anytime you see a case report involving a single person in the medical literature, you know it's either something new or very rare. In this case, it's the latter, since we know from previous reports that this bug can cause human infection and be transmitted from animals. Rare doesn't mean never, and you can't dismiss it, but C. ulcerans is just one of many bacteria that can be found in cats and transmitted to people. It's part of the inherent risk of infection that comes with cat ownership. This relatively low risk is hopefully outweighed by the benefits of cat ownership, and the cost-benefit can be maximized by basic infection control and hygiene practices. This report also shows how it's important for physicians to query pet ownership when dealing with infectious diseases in their patients, something that still needs lots of improvement.

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A recent paper about toxoplasmosis in the journal Biology Letters (Thomas et al. 2011) has attracted a lot of attention because it reports a possible link between this cat-associated parasite and brain cancer in people.

Toxoplasma gondii is a protozoal parasite. Cats are the natural host and can (but rarely do) pass the parasite oocysts (eggs) in their feces. People can be infected by ingestion of Toxoplasma oocysts that have been outside of the cat long enough (24 hours or more) to develop into an infectious form. Human Toxoplasma exposure is common, although this is typically not acquired directly from pet cats.  Adult cats rarely shed oocysts, whereas exposure from contaminated soil (e.g. from working in a garden and not washing ones hands afterward) or undercooked meat of various kinds are also important sources in different areas. Almost always, when a person gets infected, disease does not occur. Rather, the immune system contains the parasite, but is unable to kill it completely.  The parasite therefore often enters a dormant state forming small cysts in various body tissues, including in the brain.

Most concern regarding Toxoplasma involves pregnant women who have not been previously exposed to the parasite (and therefore have no antibodies to fight it off quickly). If they become infected during pregnancy, serious infection of the fetus can occur. Another problem in people is Toxoplasma encephalitis, a severe brain condition that occurs most commonly in people with compromised immune systems (e.g. HIV patients), typically from re-activation of dormant Toxoplasma. 

The recent paper by Thomas et al raises an additional concern: brain cancer. The basic premise of the paper is that some types of persistent infections might be able to induce mutations at the cellular level, resulting in cancer. Since Toxoplasma can cause longterm but dormant infection in the brain, they investigated a possible linkage.

The researchers took international statistics about malignant brain cancer from the International Agency for Research on Cancer database to determine brain cancer rates in different countries. They then compared these to Toxoplasma antibody rate data from 37 countries (from a 2006 paper that collected data from other papers). They found that the prevalence of antibodies against Toxoplasma in a country was related to the prevalence of brain cancer in the country (that's an oversimplification of what they did, since they did various kinds of statistical analyses, but that was their basic conclusion).

Some things to consider, though, before you ask for an MRI because you're a cat owner:

• This is a pretty superficial study. When I started reading it, I assumed they had done a case-control study, whereby they took a group of people with brain tumours and an equivalent group of people without brain tumours, and compared Toxoplasma antibody rates. That's not what was done. Rather, what they are essentially saying is that the incidence of brain tumours is higher in countries with a higher incidence of Toxoplasma antibodies in people. There are potentially a lot of other factors that might be involved. For example, they also showed that the incidence of brain cancer increased with increased gross domestic product (GDP) of the country, i.e. brain cancer rates are higher in wealthier countries. This could be because brain cancers are most often diagnosed as a result of more advanced medical care or that there are other lifestyle issues that might be risk factors for cancer. Toxoplasma antibody rates may be higher in high GDP countries (possibly because more people own cats, or for a number of other reasons) and thus the statistics shown an association between brain cancer and Toxoplasma antibodies.  It does NOT mean that Toxoplasma infection is necessarily causing brain cancer.  As the authors say, "This leaves open the possibility that brain cancers and T. gondii are both affected by a third correlated factor."
• This study included all brain tumours. It's hard to believe that Toxoplasma would be a risk factor for all of the various brain tumour types, if there is actually an association.
• The Toxoplasma prevalence data weren't obtained in a standard manner by the researchers. Rather, they took data from a paper written in 2006. That paper obtained the data from various other published papers, some decades old. It doesn't mean that the data are not valid, but using data from studies that collected the information in different ways and from vastly different time periods creates some weaknesses.
• Studies that are looking at a subject from a high level don't necessarily tell you what the risk is at the individual level. As the authors state "...analyses of data aggregated at the population level may not pertain to individual risk." (In epidemiology, this is called the ecological fallacy.)
• A large percentage of the human population (~1/3) has antibodies to Toxoplasma, indicating previous infection. That's a huge number, yet the incidence of brain cancer is very low overall. Certainly, even if there is a true association, the likelihood of an individual developing cancer from Toxoplasma is very low.
• Pet cats rarely shed Toxoplasma. They usually only shed for a couple of weeks of their life, typically when they're kittens. Also, the Toxoplama oocysts must live in the environment for 24 hours or longer to become infectious and a person has to ingest them to get infected. Therefore basic hygiene practices should reduce the chance of exposure even if a cat is shedding oocysts.

This is an example of a study that is great for generating questions that need to be answered, but not answering the questions. They've shown a crude association between toxoplasmosis and brain cancer. What that means is more detailed study is needed to see if the association is real (i.e. not the result of some other correlated factor) and furthermore to try to determine if the association is actually causative. Unfortunately, the press and internet don't understand that aspect and freak people out with statements such as "Cat parasite linked to brain cancer. A parasite spread by cats could almost double their owner's chance of developing brain cancer, research suggests."

One of the paper's concluding statements sums it up nicely: "Clearly, further research is necessary to determine the proximate links between T. gondii and different types of brain tumours and to investigate a mechanism of action." That means we need to work to determine what the true nature of the association is, and not panic at the possibilities.

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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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Urinary tract disease is a common reason for use (and misuse) of antibiotics. In veterinary medicine, one thing that we lack is clear clinical guidelines (particularly regarding antimicrobial use) to help manage specific types of diseases. In human medicine, there are some excellent guidelines of this kind (e.g. the Infectious Disease Society of America guidelines) available for a range of diseases, and these can greatly assist with proper management of cases.

Because of the lack of veterinary guidelines, the International Society for Companion Animal Infectious Diseases has started a guideline development program. Using a committee of international experts in the fields of infectious diseases, internal medicine, microbiology and pharmacology, from both human and veterinary medicine, and extensive discussion, debate and revision, specific treatment guidelines are being developed for different types of infectious diseases. The first set, Antimicrobial Use Guidelines for Treatment of Urinary Tract Disease in Dogs and Cats, has now passed peer-review and the guidelines have been published in Veterinary Medicine International, an open-access journal available to all veterinarians.

To download the guidelines, you can also click here.

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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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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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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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When I give presentations to veterinarians about infection control, I often talk about legal liability as one reason they need a good infection control program. I talk about the potential bad scenarios, such as someone getting an MRSA infection from an animal and then turning around and suing the vet. I usually say something like "I don't think it's happened yet, but you never want to be an index case". I may need to change that line now that a Texas veterinary clinic is being sued over a person's MRSA infection.

However, the lawsuit, filed April 4, isn't from an owner. Rather, it's from a veterinary assistant. The woman is suing the clinic, claiming they were negligent because they didn't warn her that she would be caring for an MRSA-infected animal. She claims that she contracted the infection on the job and that it "has physically impaired her for the rest of her life."

I know nothing about this case beyond what's in the link above, however it raises a few important issues and questions.

What does this mean for the veterinary clinic?

• I've been saying for years that the bar is being raised and clinics need a good infection control program, including training and education, to reduce infections of both pets and people.
• As awareness of zoonotic diseases and veterinary infection control increases, the potential for lawsuits may similarly increase.

What level of warning is required for veterinary employees?

• This varies with the type of person.
• A veterinarian shouldn't need to be informed that they will work with animals carrying zoonotic pathogens. If they didn't pick that up in vet school, they've got some other major issues.
• A veterinary technician should have a similar understanding of the risks and measures that should be undertaken to reduce those risks.
• Lay personnel are a different story. You can't assume a lay employee has any knowledge whatsoever about infectious diseases, zoonotic diseases or infection control.
• If there are minors in the clinic (e.g. co-op students, volunteers), you need to go even farther, and there should be written notification of parents of the risks, and measures that are taken to reduce the risks.
• In general, the less the veterinary education, the greater the need for clear and documented education about disease avoidance.
  

How do you prove this person acquired MRSA on the job?

• That's tough. Perhaps there was a clear link with a case. Even stronger would be showing that the human and animal MRSA strains were the same, but that's unlikely to have been done. Just because MRSA can be found in animals doesn't mean that MRSA infections all come from animals. Humans are thought to be the source of the vast majority of MRSA infections and pets, and while pets can potentially spread it back to people, this is ultimately a human disease. People pick up MRSA all the time in the general population, although the percentage  of people who carry it at any given time is still low.
• MRSA carriage rates have been shown to be higher in veterinarians than in the general public in a few different studies. I think it's clear that MRSA exposure is a risk of veterinary practice. However, proving that an individual infection came from a pet in a clinic is still difficult.

How can vet clinics reduce the risk of MRSA (and other) infections, as well as lawsuits?

• Have an infection control program in place.
• Make sure infection control practices and policies are written down.
• Make sure all employees are appropriately trained and document the training.
• Make sure people follow all of the required protocols.

Infection control isn't rocket science. At its heart, it's the application of some very basic practices. Infection control hasn't had a high profile in companion animal veterinary medicine in the past, but things are changing (albeit slowly). Available resources can help veterinary clinics implement a decent infection control program with minimal effort. A good resource is the document Infection Prevention and Control Best Practices for Small Animal Veterinary Clinics, which is available (free) for download on the Worms & Germs Resources page.

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Like any animal, disease outbreaks can occur in wild birds. Unless they are large outbreaks they often go unnoticed, but smaller outbreaks can sometimes be encountered by homeowners with bird feeders. Because bird feeders are mixing sites for birds, they are also sites of disease transmission and a place where deaths can be identified. In an outbreak, feeders can contribute to the spread of  infection between birds, and potentially be a source of infection for people or pets.

A classic example of this is Salmonella infection in songbirds. Outbreaks occur periodically and are often identified by people with bird feeders who start to find the odd dead bird in their yard. Some birds can be healthy carriers of the Salmonella bacterium (and therefore be a source of infection for others), while other birds may get sick and potentially die from the infection. If you have noted dead birds around a bird feeder, consider the potential for a disease outbreak, particularly salmonellosis.

The risk to people and pets from Salmonella outbreaks in birds is reasonably low, and probably greatest in cats. Most reports of songbird-associated salmonellosis (songbird fever) are in cats, because cats are more likely to catch and eat songbirds. Sick birds are easier to catch, further increasing the likelihood of exposure during an outbreak. Exposure is also possible through scavenging already-dead birds and perhaps from exposure to heavily contaminated surfaces or spilled feed around feeders.

General recommendations during an outbreak of salmonellosis in songbirds include:

• Keep cats indoors. This is a good idea at any time, but if you have an indoor-outdoor cat, keep it indoors if there might be an outbreak underway.
• If your pet has been exposed to a sick bird or an area where sick or dead birds have been found, and your pet gets sick, make sure you tell your veterinarian about the birds.
• Clean the bird feeder and then disinfect it by soaking it in 10% bleach for 30 minutes. Rinse it after the bleach treatment. If the feeder is difficult to properly disinfect (or you don't want to try), get rid of it by double bagging it and putting it in the garbage.
• When cleaning the feeder, do it outside so that you don't contaminate any household surfaces. When handling the feeder, wear disposable gloves and wash your hands after you remove the gloves.
• Keep the feeder down for 1-4 weeks. This reduces the concentration of birds in the area and may help reduce mingling of sick and healthy birds.
• Remove any dead birds by burying them at least two feet deep in a flowerbed (not in a vegetable garden!).  This is not very easy or practical however - alternatively, double bag the bodies and put them in the garbage, avoiding direct contact with the birds and washing your hands afterward.

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ProMedMail tends to publish a monthly rabies report. While a lot of it involves the same basic issues, there are sometimes a few more interesting stories:

Rabies in a donkey in Georgia

• Like all mammals, donkeys are susceptible to rabies virus but infections are not particularly common. Raccoon rabies has also be identified in the area, and a bite from a raccoon may have been the source.

Bite from a rabid kitten in Pennsylvania

• A York County woman was bitten by a kitten that ran into her house when the door was opened for someone else. The kitten bit her when she grabbed it to throw it (hopefully not violently) back outside... an understandable reaction but not what you want to do in a case like this. You need to know whether a wild animal that bites is rabid, and if it gets away, you can't test it. You need to get away from it but keep it contained until someone can come get it. The other problem with people getting rid of the animal is that they might not recognize the risk of rabies. In this case, the kitten was hit by a car after being removed from the house, which allowed for it to be tested.

Yet another report of a dog being exposed to rabies through contact with wildlife, then being euthanized because it was not properly vaccinated.

• An unvaccinated animal that has been exposed to a rabid animal has to be euthanized or undergo a strict six-month quarantine. A vaccinated animal only needs a 45-day observation at home.

Rabid bobcat attack in Florida

• Encountering a manic bobcat isn't something I'd like to do, and a LaCrosse, Florida woman spent nine days in hospital after being attacked by one. The 25-pound cat was trying to get the family's cat, then lunged at the woman when she came outside the house, aiming for her neck. Her husband then shot it. They knew that the bobcat needed to be examined, and took the rather unusual approach of bringing it to the hospital emergency room with them (I'd love to have seen that). I don't imagine hospital personnel did anything, but Florida Fish and Wildlife Conservation Commission personnel came and got it, and later confirmed that it was rabid. (Image: Lynx rufus, US Fish & Wildlife Service)

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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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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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A few days ago, I wrote about tuberculosis (TB) exposure in several people who performed a necropsy on an infected dog. As part of that investigation, a cat in the household was tested and was also positive for TB. It was euthanized because of the public health concerns. A logical question from a reader was "Is there no treatment for animals, as there is with humans?"

Diagnosis of tuberculosis in an animal often results in prompt euthanasia, and some individuals and groups have euthanasia as a standard recommendation.

Why?

• We have no data about how to properly treat an infected animal.
• We have no data about how effective (or ineffective) treatment may be.
• It's not easy to test animals before or during treatment to see if they are shedding the TB bacterium (Mycobacterium tuberculosis).
• It's such a concerning disease in people that the inclination is to err on the side of caution when it comes to public health.

Is it an appropriate response?

In some circumstances, it probably is. In other circumstances, treatment shouldn't necessarily be dismissed. A major problem is the knowledge gap.

• We don't know whether infected animals pose any risk to people. Human-animal transmission can occur, but it's unclear whether animals can transmit the infection back to people.
• If transmission between pets and people occurs, we don't know what circumstances are involved. TB is not readily transmitted even between people. Short term exposure is not a major concern. It's likely that close and prolonged contact is required for transmission from pets, but we don't know for sure.
• We don't know if certain infected animals are higher risk than others, although there probably are differences. A dog with respiratory TB and active disease is probably a much higher risk than a dog with a localized TB abscess.
• We don't have easy and accurate ways to test pets for TB exposure and shedding. In people, sputum cultures are tested by having people spit in a cup. Getting a sample like that is obviously difficult in dogs. Collecting a good sample for testing is much more involved in pets and not amenable to routine testing (for research or monitoring).
• We don't know for how long to treat a pet with TB, or which drugs are optimal for use.

Treatment might be reasonable when there is an animal with mild disease (or no signs of disease), when the animal was infected from a household contact (meaning that some degree of TB exposure has already occurred in the household and the dog would probably only be a secondary source of exposure), when there are committed owners who are willing to embark on time consuming and expensive treatment, when owners are able to keep the dog away from other animals and people during the treatment period, and when there is an understanding that treatment may not work.

When might treatment not be a good idea?

• When the animal is shedding the TB bacterium in respiratory secretions.
• When the owners cannot afford prolonged and expensive treatment and monitoring.
• When the owners cannot be relied on the administer every dose of medication and make every required follow-up appointment.
• When owners cannot be relied on to keep the dog away from other dogs and animals (and people) during the treatment period (or at least during the initial period).
• When there are high-risk people in the household, such as people with HIV.
• When serious disease is present, such that the chances of recovery are low.

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The Swedish Veterinary Association has released an English version of their 2009 "Guidelines for the clinical use of antibiotics in the treatment of dogs and cats". It's a very comprehensive document that goes through various medical conditions and discusses antibiotic use recommendations. As concerns about antibiotic use and misuse increase, more organizations are putting the significant effort that is required into developing such guidelines, and they can be a tremendous asset. While there are still significant limitations in the available research needed to produce evidence-based guidelines, a combination of careful review of existing information and expert opinion can provide good guidance for treatment of infections in companion animals.

There are always a few disclaimers that need to be given when presenting antibiotic use guidelines:

• They are guidelines, not standards. They provide a general overview of the issues and how to manage most patients, but some patients don't read the book and need to be treated differently.
• Disease and drug resistance patterns vary between regions. These patterns need to be considered, particularly when considering guidelines produced in another area or country.
• Things change over time. As guidelines age, some parts of them may become less relevant.
• There are differences in antibiotic access and licensing between regions.

Regardless, sound guidelines like these are needed and will hopefully help improve both patient care and control of the scourge of antibiotic resistance.

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A large whooping cough (pertussis) outbreak has been ongoing in people California in 2010. This bacterial infection, caused by Bordetella pertussis, is a highly transmissible disease that can result in serious problems (including death) in young infants. At last report, there were over 6000 cases of whooping cough, making this the largest outbreak in 60 years. Over 200 infants have been hospitalized, and there have been at least 10 deaths. Nine of the 10 deaths were in infants less than two months of age.  Infants in this age group have little to no immunity to the disease because they haven't been vaccinated, and they are more prone to severe complications.

Bordetella pertussis is a human bacterium. It does not infect animals and animals are not direct sources of infection. (Actually, experimental infection of neonatal puppies with large doses of B. pertussis can result in shedding of the bacterium by a small percentage of dogs, but that's not particularly relevant to the normal household situation). Therefore, people don't need to worry about infecting their pets and pets passing the infection on to other people. However, it's not impossible that pets could play an indirect role in transmission. A pet's haircoat could possibly become contaminated with the pertussis bacterium from someone coughing around it, or touching it with contaminated hands. The bacterium could survive on the haircoat for a while (probably days), and someone could potentially get the bacterium on their hands by petting it, and subsequently become infected.

What are the odds of this happening? Who knows. It's not something that anyone has investigated, as far as I know.

Could dogs and cats be important sources of pertussis in households? Probably not. I assume that if there is a person with whooping cough in a household, that person is more likely to be the source of infection for other people than a pet. 

Could pets spread pertussis outside the home? That might be a more realistic concern. People with pertussis might keep themselves away from others and stay at home, but if they contaminate their dog's coat and the dog meets people on a walk or at the park (or at a veterinary clinic, or anywhere else), I have to wonder whether there could be the potential for spread of the disease.

What should we do about this? Common sense should prevail, and itt's important for pertussis as well as other diseases. If someone in the household has an infectious disease that is transmissible and for which a pet could potentially be a vector, some basic precautions should be taken. Good attention to hygiene might help reduce contamination of the pet's haircoat. This includes regular handwashing (especially after coughing and before petting an animal), avoiding coughing close to the pet and not letting the pet sleep close to the person's head. Keeping the pet away from people outside the house, or at least limiting it's contact with high-risk people might also be useful. In particular, keeping pets that might have been contaminated away from infants would be wise.

Overall, the risks are very low. We don't need to fear dogs and cats as potential pertussis vectors. However, in the absence of proof that there's no risk, and with a highly transmissible and potentially serious disease, use of some simple infection control measures makes sense.

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ProMed's monthly rabies update contains some recurring themes:

• A couple of incidents of dog versus rabid raccoon. The dog usually comes out on top, but the raccoon can exact revenge at the end of the day through the need for quarantine or euthanasia. If the dog is not vaccinated, a long quarantine or euthanasia is required. If the dog is vaccinated, only a shorter observation period is needed.
• A rabid skunk was found wandering around during the day with a wobbly gait and drooling. Any wild animal that is acting strangely should be considered rabid until proven otherwise. They don't have to be showing signs of severe neurological disease. Something as simple as not being afraid of people or wandering around in areas or at times when they would not usually be found should raise the suspicion.
• A child who was sleeping outside woke up to "find a raccoon, kind of, scratching at his leg." (I  assume they mean it was "kind of scratching at the kid's leg," (whatever that means), instead of it was "kind of a raccoon.") The raccoon wasn't caught for testing but the child is undergoing post-exposure treatment because a normal raccoon wouldn't be expected to do that, so there is a significant chance of rabies exposure. Scratches are not high risk since rabies virus does not live in the claws, however it is possible that saliva from the raccoon could have been present on the animal's feet or the raccoon could have licked the child before scratching, such that the scratches could have then inoculated rabies virus into the tissues.
• A couple of reports of rabies in rabid kittens. These cute little rabies vectors cause repeated problems, and lead to public alerts notifying anyone who may have handled the kittens to get evaluated to see if they need post-exposure treatment. Handling of strays should be avoided.
• A family received post-exposure treatment after being bitten by their rabid cat. Vaccination of pets is not just for the health of the pet. It's to reduce exposure of people as well.

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Pasteurella multocida is a bacterium that is commonly found in various pet species. It typically inhabits the upper respiratory tract of healthy pets, although it is an important cause of respiratory disease in rabbits ("snuffles"). It is also a zoonotic pathogen, and human infections are sporadically reported. Most are associated with bites, mainly from cats. Others have involved pets licking wounds or broken skin. Infections seem to be a particular concern in people undergoing dialysis because of kidney failure. Infections have been associated with things like cats chewing on dialysis tubing and pets having contact with catheter sites.

A recent report described another dialysis-associated infection in person with chronic kidney disease and diabetes (Satomura et al 2010, Ther Apher Dial). The person developed peritoneal dialysis-associated peritonitis. Peritonitis is infection of the internal lining of the abdominal cavity (the space between the intestines/other abdominal organs and the body wall). For peritoneal dialysis, a catheter is left in place which passes through the body wall, and infections can occur from bacteria migrating through or along the catheter and into the peritoneal cavity. In this case, Pasteurella multocida was isolated from the infected peritoneal fluid. The source of infection wasn’t clear, and no obvious risk factors like a cat gnawing on the catheter were reported. However, the same bacterium was isolated from a throat swab taken from the person’s cat. Given how common this bacterium is in cats, how uncommon it is in people, and previous reports of cat-associated infection, it’s logical to assume that the cat was the source.

The fact that no clear risk factors were identified in this case highlights the ever-present (but still relatively low) risk to people with dialysis catheters who have contact with cats. Certain things like keeping the cat away from the catheter site and other dialysis items are common sense and presumably very important. However, general hygiene measures are also probably very important. It is logical that a cat owner could frequently get this bacterium on his or her hands from regular interaction with the cat, or potential from contact with objects like food and water bowls. Good attention to hand hygiene, especially before touching the catheter or any dialysis items, must not be overlooked, and should be an important part of counseling of dialysis patients who own pets. Unfortunately, the risks associated with pets are not always discussed by physicians (who may not even ask about pet ownership), so some people don’t get the required information.

Note: Image is from http://www.kidney.org.uk/kids/crf/page09.html. It's presumably meant to be a cute image showing a happy (and otherwise healthy) kid undergoing dialysis. It's interesting that they show a cat in the picture, but no where on the page is there any mention about infection control measures that should be taken around pets. It seems like a missed education opportunity to me.

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The Philippine Information Agency has issued a press release detailing a rabies vaccination program for 5000 public school children in the province of Camiguin. This is prophylactic (preventive) vaccination, not post-exposure treatment.

Routine rabies vaccination is recommended for people at increased risk of exposure. Classically, this involves veterinary personnel, people working with wildlife, people working with strays or feral animals, and similar groups. Routine vaccination of the general public is not used because of the high cost and low need, given the average person's low risk of exposure and the availability of effective post-exposure treatment. By providing vaccine prophylactically, authorities are implying that the rabies exposure risk is quite high for these children.

A Camiguin health office official is reported as saying that the pre-exposure series, consisting of 2 doses, will save money compared to the post-exposure regimen of 4 doses plus a shot of anti-rabies antibody. However, that doesn't make any sense. From a cost standpoint, prophylactically treating everyone with 2 shots only saves money if over half of the population would otherwise need 4 shots. I know rabies is a problem in that area, but certainly half of the kids in the area won't exposed. Further, what really blows a hole in this reasoning is the fact that a vaccinated person who is exposed to rabies should receive a booster series of 2 vaccines regardless, thus bringing the total to 4 shots. People who have been vaccinated don't get the antibody shot if they are exposed, so that does save a little money.  (On a side note, routine vaccination usually involves 3 doses, and the release says people will get two doses but will get vaccinated on days 0, 7 and 21 or 28. That's 3 doses, which makes the math even more questionable). 

If rabies is epidemic in the area, if it's not being controlled well by other means and if there is rampant exposure of children, vaccination may be a reasonable option. However, rabies is basically 100% preventable with proper post-exposure treatment. Rabies deaths are usually because people don't seek, or are not given, proper treatment in a timely fashion. Educating the public to reduce the risk of rabies exposure and to seek medical care, ensuring that there is adequate awareness about rabies among medical personnel and ensuring that adequate vaccine and antibody is available for exposed individuals seems to be a much more logical approach

I was actually wondering whether this press release was real. I did some searching and this agency is an official government agency and a member of the presidential communications group. It would be really nice to see more details about why this decision was made, particularly some of the evidence that was used to determine that this was needed.

It's important to take rabies control seriously. The main problem with rabies in many areas is a lack of effort or adequate resources directed against stray animal control, animal vaccination, public education, medical education and availability of proper treatment. Working on those would seem to me to be a better approach than an expensive and somewhat questionable mass vaccination program of children. The reasoning in the press release is that kids might not report bites, and that is a good point to consider. But, does that actually occur and can it not be controlled by better education?

What's the cost-benefit of rabies vaccination in a situation such as this? It's hard to oppose vaccination of this fatal disease, but are there other ways to provide better overall protection?

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Pets at work are an often contentious issue. Some people would love to take their pets to work with them to avoid leaving them home alone all day, to save money on doggie daycare, to be able to socialize with their pet during the day, and because they think "everyone will love seeing my dog."

Having pets in a workplace could be a great way to improve employee morale and for some people could be a recruitment tool. It might boost productivity if people are happier and not rushing home because they think their dog's bladder is about to burst (or, more likely, their floor is about to get peed on).

However, it could also be a great way to create strife and legal concerns. Personally, I have no problems walking into a store and seeing a dog or cat wandering around. That being said, I have above-average exposure to animals and am not deathly afraid or allergic. I'm also (currently... hopefully) not highly immunocompromised and at increased risk of an infection from a pet.

No two workplaces are exactly the same. Some businesses might be able to do it right. Some might not. Some might be willing to put the effort into it as a way to boost morale and attract good employees, some might think it's a hassle worth avoiding. If a company allows pets or is thinking of allowing pets in the workplace, they need to consider some important points:

• Are any people that MIGHT come into contact with the animals fearful or allergic? This is difficult to determine unless you have a small workplace and good communications. People that are allergic or fearful might not voluntarily offer that information because of various reasons, so just saying "if no one raises a concern, everyone's happy" doesn't always work.
• Will there be any potential contact with the general public? If so, that complicates matters greatly.
• Are there ways to properly contain and control the pets? Will the pets be allowed to roam free, be kept in the owners office, or be kept in a dedicated kennel area, away from anyone who doesn't want to see them? The more they can be contained, the better. Ideally, there would be a kennel area away from anyone who doesn't want to be in contact with the animals, but close enough that it is easy for owners to check on their pets and take proper care of them.
• Will having pets there be a disruption to the owner or other employees? A happy workforce is more productive. That's the ideal situation. A workforce distracted by a playful puppy or a cat who loves to flop across your keyboard may not be as efficient.
• Is there an area where a dog can be safely walked to urinate and defecate?
• Are there any reasons that having a pet there causes an unacceptable public health concern (e.g. restaurants).
• Is the business willing to accept the liability issues that come with having animals there? If a pet bites or scratches someone, the business' name will be first and foremost on the lawsuit, I assume.
• Will the business create a written protocol to address animals in the workplace? This would cover things like where to keep the animal, how to handle it, preventive medicine requirements (e.g. rabies vaccination), when the animal can't come to work (e.g. when it's sick) and other relevant factors.
• Is there a way to modify the policy over time if something happens? For example, if a new employee is hired and is severely allergic, will the rules be changed? If so, are people notified up front that while they may be able to bring their pets to work now, that can change at any time?

If the workplace can't consider and address all of these areas, then pets are clearly not appropriate. If they can, then there may not be a problem. The key is thinking about these issues in advance, not after:

• the pet has bitten some who is now upset, threatening to sue and demanding proof of rabies vaccination
• a person that gets fired claims their poor job performance was because they were afraid of the dog and also afraid of speaking up about it
• the dog causes a disease outbreak
• the public health department comes in to investigate an inappropriate situation

Photo credit: James Cheng (source: www.msnbc.msn.com)

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TheNorthwestern.com has an interesting article about "10 things not to do with pets in a vet's waiting room." They're all good points, and I've put an infectious disease/infection control spin on them below:

1. Don’t fail to contain your cats. Even if your cat is the sweetest thing on record, some other animals may not agree. The last thing we want is to see in our lobbies is an altercation in which one animal dies. Cat carriers are cheap and widely available. Use them.

2. Don’t give dogs free reign.  Don’t use retractable leashes!

• You wouldn't (hopefully) go into an emergency room and lick the face of the person puking in the corner or the kid hacking up a lung. Your pet's not as discriminating. Some pets are at the vet because they are sick. You don't want your pet to get what some other pet has. Also, not all dogs and cats are social, especially in a strange environment. You don't want to change your vaccination appointment to a "vaccinate and stitch up the big wound on my dog's face" appointment.

3. Don’t bring in animals you cannot personally control.

• As above. Lack of control equals increased risk to other animals, your animal, and potentially other people.

4. Don’t do the puppy park meet-and-greet thing. The vet’s is not the dog park. It’s a strange environment in which pets don’t always act the way you expect them to. Moreover, in a veterinary hospital the onus is on the doctor’s staff to keep your dogs safe. Please keep all pets apart. After all, no matter how well you know your pet, can you honestly say you know someone else’s?

• Same as above. More mixing and more contact equals a greater risk of disease transmission. That's acceptable in many situations where the risk of coming into contact with an infectious animal is low, but the odds are higher in a place where sick animals congregate.

6. Give the cell phone rest. In a place as potentially anxiety provoking as the vet hospital, cell phones can be a hazard. Even if you don’t feel the anxiety, your pet certainly does. She deserves the comfort of your undivided attention for her safety and her stress level.

• Not really an infectious disease issue but it's annoying.

7. Don’t walk a dog into a packed waiting room. If the lobby is crammed wall to wall with pets, don’t chance it. Ask someone to let the receptionist know you’re waiting outside. Or use your cell phone for something really useful for once.

• Good point. I'd take that a step further. Don't take a potentially infectious pet into a waiting room, packed or not. If you have an animal that might have an infectious disease (e.g. diarrhea, sudden onset of coughing and/or sneezing) it would be ideal to call when you arrive so they can take your pet right back to an exam room or isolation for examination. That way, if your pet is infectious, you won't expose other animals. We're trying to get more clinics to be proactive about doing this, and hopefully your clinic would mention it, but if they don't, feel free to bring it up yourself.

8. Don’t fail to tell the receptionist ahead of time if your pet is severely anxious or aggressive. All hospitals appreciate the warning when you make your appointment. It gives us a chance to offer you back-door alternatives or other concessions to your pet’s unique behavior issues.

• Good point. "If your pet is severely anxious, aggressive or might have an infectious disease" would be better.

9. Don’t bring small children unless you can’t help it. A busy animal hospital is tough on small kids. They’re not old enough to benefit enough from the educational experience relative to their risk of getting hurt.

• Sometimes you have to, but if you can avoid it, that's preferred. Vet clinics can be busy. There are a lot of animals around and it may be hard for a child to resist reaching out for another animal. I haven't seen any data on bites and scratches in waiting rooms, but they certainly occur. As well, if you are distracted by your child, you may not be able to tell your vet all the relevant information or ask all the questions you have.

10. Don’t be rude. Courtesy is king. Kill them with kindness. I shouldn’t have to offer so many versions of the same cliche, but the fact that they all exist is fine testament to their utility.

• Again, not necessarily an infectious disease concern, but really being polite and considerate to those around you applies to just about any situation, and generally makes everyone feel better and makes things go smoother.

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A cat from Ennis, Montana, has been identified as the area's first case of plague in a pet cat this summer. Plague is a disease that conjures up images of medieval pandemics and calls of "bring out your dead" (along with calls of "I'm not dead yet" from Monty Python fans).This bacterial disease, caused by Yersinia pestis, is not just of historical interest, however. It is still an important disease in some regions. In the US, it is present in wildlife in parts of the southwestern US and circulates in wild rodents. Domestic pets mainly become infected through eating infected rodents, but the bacterium can also be spread by fleas.

Cats are quite susceptible to plague, and can develop classical bubonic plague, septicemic plague or pneumonic plague, and only about 33% of infected cats survive. Dogs are relatively resistant to the disease.

Transmission of plague from pets to people is uncommon but most often involves cats. Veterinary personnel and pet owners that care for sick cats are at highest risk. While transmission from cats to people is rare, about 20% of people infected from cats die, so it certainly warrants some precautions.

In areas where plague is present, cat owners should consider the following:

• Keep cats indoors to prevent them from hunting and eating rodents.
• Keep rodents and other wildlife out of the house.
• Have a flea control program in place to prevent or treat flea infestations in pets.
• Never catch and keep wildlife (e.g. prairie dogs) as pets.

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I had an advice call the other day about two cats that were found with a dead bat. One cat was vaccinated against something (not sure what or when) while the other cat was unvaccinated. This is a situation that, if managed properly, can be very minor, but if handled improperly, can be a major problem, even resulting in death of the animals.

Bats are notorious rabies vectors. The odds of this bat carrying rabies are probably low, but they are not zero and a rabid bat is going to be more easily caught than a healthy bat. Any contact of an animal with wildlife in areas where rabies is present is considered a possible rabies exposure unless proven otherwise. The only way to do this is to have the bat tested.

If the bat is tested and is negative, then everything's fine. If it's positive, then the vaccinated cat would need a rabies booster vaccine and would have to be observed at home for 45 days. The unvaccinated cat would need a strict six month quarantine or would have to be euthanized. So, it's clear that the rabies status of the bat and the vaccination status of the cats are crucial.

Here's what to do in a case like this:

• Get the bat. The bat needs to be tested so you have to maintain control of it. Don't let the cat eat it or run off with it. Don't leave it outside where a person or animal could walk off with it. Put it in a bag or container, without having direct contact with it (e.g. use gloves or a scoop to pick it up). Be very careful if it's not completely obvious that the bat is dead, because an injured bat might look dead but still be able to bite.
• Submit the bat for testing. In Canada, that's done through the Canadian Food Inspection Agency. Make sure they know that an animal has been exposed to the bat. They would not likely test the bat if there was no exposure. They can be contacted directly or through your veterinarian. There is no charge for testing.
• Find out the vaccination status of the cat(s). You need to know when the last rabies vaccine was given and what type of vaccine was used (1 year or 3 year). You need to be able to demonstrate that the pet is current on its rabies vaccination if the bat is positive and you want to avoid the long quarantine.
• Figure out why/how/where the cat(s) caught the bat, and whether that can be avoided in the future.

(click image for source)

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Peritoneal dialysis is used to treat some people with chronic kidney failure. Infection is a major concern, particularly peritonitis (infection of the lining of the abdomen) because peritoneal dialysis involves having an indwelling catheter that goes through the skin and body wall directly into the abdominal cavity.

Infections can occur from bacteria that inadvertently get flushed into the abdomen during dialysis treatment or potentially migrate along the side of the catheter. Accordingly, most infections associated with peritoneal dialysis are caused by bacteria that are found on peoples' skin, such as Staphylococcus aureus.

While the vast majority of peritoneal dialysis infections are human-associated, infections from pets have been reported. Multiple different pet species have been implicated, even hamsters - one case report described an infection in a child that was thought to be caused by a hamster that slept in the same bed as the child (Campos et al 2000).

A recent study in the journal Seminars in Dialysis (Broughton et al 2010) involved a review of the scientific literature for reports of pet-associated peritoneal dialysis infections, as well as a review of records from the authors' peritoneal dialysis unit.

In their review, they identified 124 reported infections caused by zoonotic microorganisms in the literature, involving 12 different microorganisms. The most common microorganisms were Campylobacter, Pasteurella, Zygomycetes, Neisseria, Rhodococcus, Listeria, Mycobacterium avium complex, Capnocytophaga spp, Salmonella, Brucella and Bordetella bronchiseptica. However, only a subset of these were probably associated with pet contact, and retrospectively determining the sources is quite difficult for some. For example, Campylobacter and Salmonella could as easily (or more easily) come from contact with raw meat as from pets. Infections were fatal in 13.5% of cases, demonstrating why this is an important issue.

The most common bacterium causing convincing pet-associated infections was Pasteurella, which can be found in the mouths (and other places) of healthy pets. It is a common cause of pet bite infections and it makes sense that Pasteurella could contaminate pet owners' hands or the dialysis catheter site. In the study of their own hospital's cases, the authors found similar findings, with a low rate of zoonotic infections and a predominance of Pasteurella among those.

Literature reviews aren't a great way of determining the true scope of a problem, because they require people to:

1. identify the infection
2. identify a pet as a possible source (often the weak link; furthermore, identifying an infection caused by a potentially zoonotic microorganism doesn't necessarily mean a pet was the source)
3. decide to write a case report
4. get that case report accepted by a journal

Studying medical records has limitations as well, since steps 1 and 2 still need to be performed (with the weak link again being thinking about a pet-association). So, care should be taken when interpreting the results of this study. However, while the results indicate that pet-associated peritoneal dialysis infections do occur, they are probably relatively uncommon.

While pet-associated infections are likely uncommon, any peritoneal infection can be a major problem, so common sense measures that would likely reduce the risk should be used:

• Avoid contact of pets with the dialysis catheter and catheter site
• Wash hands after having any contact with pets
• Don't let pets sleep in the bed
• Wash hands before touching the catheter

Additionally,

• Physicians should be aware of the potential for pet-associated infections, and pet contact by their patients
• If a pet (usually a cat) bites the tubing, this should be reported to a physician ASAP and preventative treatment for infection might be indicated
• Initial antibiotic therapy choices should cover common pet-associated pathogens if there is a history of contact of pets with the catheter or tubing.

People with peritoneal dialysis catheters shouldn't fear their pets, and there is no need for these people to get rid of pets (although they should avoid high-risk pets like reptiles). Pet owners are presumably at somewhat higher risk than non-pet-owners, but the risk appears to be fairly low. In most situations, the positive aspects of pet ownership probably outweigh the risks.

Image: Schematic diagram of peritoneal dialysis (click image for source)

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Methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. pseudintermedius (MRSP) get a lot of media attention because of the ever increasing numbers of infections in dogs and cats, and concerns about transmission to people. However, there are many other methicllin-resistant staph of varying relevances. One is an interesting related bug called Staphylococcus schleiferi.

There are actually two types of S. schleiferi:

• S. schleiferi schleiferi: This is a coagulase-negative subspecies that occasionally causes skin and ear infections in dogs (and uncommonly cats). It can also be found in healthy animals. There are a few reports of infections in people, mainly surgical site and wound infections in individuals who are at high risk of infection because of hospitalization, surgery or other factors.
• S. schleiferi coagulans: This is a coagulase-positive subspecies that may be more common in dogs and cats than S. schleiferi schleiferi, causing skin and ear infections and also being found in healthy animals. Human infections are very rare.

Currently, there is little to no evidence the animals are a source of human infection with S. schleferi and human infections appear to be very uncommon. However, this is an area that hasn't been studied much so it's hard to say with any confidence that there is no risk. My assumption is that the risk is very low, but not zero, so while we shouldn't be paranoid, it makes sense to use some very basic infection control practices when dealing with infected animals to reduce any possible risk. These would include:

• avoiding contact with infected sites
• if contact with infected sites is necessary (e.g. cleaning or treating infected ears), gloves should be worn and hands washed after glove removal
• hands should be washed thoroughly after any contact with the infected site, and regularly after contact with the animal

Quarantine of infected animals in households isn't necessary, because of the limited evidence of transmission and because healthy dogs and cats can also carry this bacterium. In veterinary clinics, isolation of infected animals is reasonable because other animals in the clinic may be at higher risk of developing infections should they become exposed.

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There's an interesting article in today's Pittsburgh Post-Gazette about Scooter, a paralyzed cat in a custom-made cart, that visits patients at HealthSouth Harmarville Rehabilitation Hospital. It's a nice story and it's easy to see the potential appeal of a paralyzed animal whipping around a rehab hospital as an inspiration to patients.

Obviously, people like having this cat in the hospital, and he's helped some patients. That's not surprising because we know that pet therapy can be beneficial to many. My concern in this case is for the cat's health, and the heart of the issue is whether the benefits to patients are because Scooter's a paralyzed cat or because he's a cat, and whether the benefit to patients justifies the risk to the cat.

Paralyzed animals are at increased risk for certain infections. In particular, they are at very high risk for urinary tract infections. These animals tend to get recurrent urinary tract infections and enter a downward spiral of infection / treatment / infection / treatment / resistant infection / treatment / more resistant infection... and in some cases end up with infections that are very difficult or impossible to eliminate. In some cases, urinary tract infections in paralyzed individuals can result in infection spreading to the rest of the body, which can be fatal.

Back to my concerns for Scooter: We know that the hospital environment is contaminated with various drug-resistant bacteria. We know that patients in hospitals are often carrying drug-resistant bacteria. We know that dogs that participate in visitation programs are at increased risk of acquiring drug-resistant bacteria. So, do we really want to be exposing a high-risk animal to such an environment, and potentially speed up the cycle of infection that could ultimately cause severe illness or even death in the animal?

There's no clear answer, but we need to consider the risks to visitation animals, and whether the novelty of having a paralyzed cat (instead of a normal, healthy cat) visiting patients is really a significant enough benefit to justify the potential risk to the cat.

Image: A paralyzed cat using a mobility cart (source: www.k9-carts.com)

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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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A couple of more Salmonella recalls have occurred recently. Feline's Pride Natural Chicken Formula, a raw chicken diet, has been recalled, as has Natural Balance Sweet Potato and Chicken, a kibble diet.

Finding Salmonella in commercial raw diets is expected and I'm surprised about the recalls that have happened. If you buy raw meat, you need to assume that it's contaminated with Salmonella and various other potential pathogens. Salmonella in kibble diets is more surprising, and is a concern because people do not tend to handle kibble as potentially contaminated.

These recalls highlight a few points to me:

• Always assume you have Salmonella and other nasties in raw meat. Careful attention to handling of raw meat and personal hygiene (e.g. handwashing) is critical.
• While lower risk, kibble is not innocuous, so wash your hands and prevent cross-contamination of kibble with human foods.
• "Natural," along with "organic," "super premium" and other marketing catch-words tell you nothing about the quality and safety of a product. There's no evidence that any products marketed as organic, natural, or anything else along that line are at all superior to diets produced by reputable companies, particularly diets that have undergone proper development and testing, including AAFCO feeding trials.

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People like to talk about the "one medicine" concept. It's a great concept, but my big issue with it is there's a lot of talk but not a lot of action.

One way of thinking about "one medicine" in terms of people and pets is to focus on the health of the entire household as a whole, because:

• People can transmit infections to pets.
• Pets can transmit infections to people.
• People and pets can be infected from the same source.
• Infection in a pet or person may indicate that others in the household are also at risk.

It's a complex dynamic. When I speak about this topic, I use a couple of different ways to make the point. One is the concept that we are not a population of people living with dogs, cats, horses etc. - we are a population of animals. Similarly, I sometimes say "pets are people too, at least microbiologically." What I'm saying is that we can't focus just on humans or just on pets. The household as a whole needs to be considered, and care of the health of the all of its members - human and animal - needs to considered together.

What does that really mean?

Physicians need to be aware of the presence of pets in the household and other animal contacts. This information might be important when considering certain diseases. For example, if someone comes to their physician with flu-like symptoms and their physician knows they have pet birds (especially psittacines), then the physician would hopefully consider psittacosis. This disease is caused by Chlamydophila psittaci, a bacterium that can be carried by healthy birds. Not realizing there is a bird in the household can lead to a missed diagnosis.

Veterinarians need to be aware of the health status of people in the household. People with close contact with the human healthcare system and people with compromised immune systems are more likely to be carrying certain infectious agents. They are also more likely to pass these pathogens on to their pets. Therefore, knowing the health status of the owner might lead the veterinarian to consider different diseases in the pet, thereby improving diagnosis. Conversely, people with compromised immune systems are at increased risk for various infectious diseases from pets. If the veterinarian knows a pet owner is at increased risk, they can provide better advice about disease prevention measures to protect the owner. Veterinarians rarely ask owners about their immune status, including pregnancy (even the "how far along are you?" question is dangerous, because eventually you're going to get the "I'm not pregnant!" response.) Ideally, people should have a positive, comfortable relationship with their veterinarian, realize that their veterinarian is a member of their (and their family's) overall healthcare team, and therefore tell their veterinarian about any relevant health issues. For this to work, they need to understand the value of this communication, trust their veterinarian and know that their personal details will be kept confidential. At the same time, the veterinarian needs to understand the issues and need for such information, and have a plan on how to use it.

Veterinarians and physicians need to communicate better. They need to know who to contact when necessary and be able to do it efficiently. This is also relevant for non-infectious disease issues. For example, there could be a situation where a veterinarian has had to euthanize a pet: the veterinarian may realize that the owner is quite distraught, but can't do much beyond offering condolences and providing contact information for resources to help them out. The physician may not know anything about the situation, but it could be of significant relevance to the person's health. If nothing else, the physician could be notified that there's a potential concern. There are privacy issues that need to be considered and sorted out, but a little conversation can go a long way. The ability of veterinarians and physicians to contact each other about relevant issues can help prevent problems with miscommunication, provide general information about certain topics and help provide optimal patient care.

One medicine needs to be one medicine in action, not just in theory.

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When multiple studies report the same results, it gets more and more convincing that the findings are true. This is becoming the case with antibiotic use as a risk factor for methicillin-resistant Staphylococcus aureus (MRSA) infections in dogs. Late last year, I wrote about a study of ours that identified prior antibiotic use as a risk factor in dogs for infections caused by MRSA versus those caused by methicillin-susceptible S. aureus. Recently, a similar study was published, with some similar results. This study (Magalhaes et al, Vet Res, 2010) compared dogs and cats and with MRSA infections to a group of dogs and cats with susceptible infections. They found that MRSA infections were associated with:

• the number of antimicrobial courses
• the number of days admitted to veterinary clinics
• having had surgical implants

Additionally, animals with MRSA infections more often had had contact with people that had been in hospital, but the difference was not statistically significant.

That's two studies that identified antibiotic use as a risk factor for MRSA infection. It makes sense biologically, and it's likely that antibiotic use is an important driving force for MRSA infection in pets (like it is in people).

How do we reduce the likelihood of MRSA infections? It's pretty clear that reducing antibiotic use is a key factor. Antibiotics are important drugs and are certainly needed in many situations, but they're also prone to overuse and misuse. Here are some things that can (and need to) be done:

• Only use antibiotics when necessary. Antibiotics are often used without evidence of a bacterial infection and in situations where bacterial infections are uncommon (e.g. urinary tract disease in cats, viral upper respiratory tract infections).
• Use logical and prudent peri-operative antibiotic regimens. Only use antibiotics for surgeries when there are actually needed, and only for as short a period of time as possible.
• Ensure that proper doses are given (and actually get into the animal). Unfortunately, underdosing (and overdosing) of antibiotics are not uncommon.
• Promote more research regarding effective antibiotic treatment regimens. We often use much longer courses of antibiotics in pets compared to people, in part because we have no research data telliing us whether we can use shorter treatment courses.

Another thing to consider is the fact that these studies looked at factors for methicillin-resistant versus methicillin-susceptible infections. Therefore, a dog had to have an infection to be included. While certain things are risk factors for MRSA versus susceptible infections, there are other factors that increase the chance of any infection, and reducing these will also help reduce the risk of MRSA (and other) infections (i.e. if your dog doesn't get an infection in the first place, it won't have an MRSA infection).  One very important factor is proper management of underlying skin diseases, such as controlling atopy, flea allergy dermatitis and food allergy. Proper wound care, good veterinary clinic infection control practices and myriad other factors probably also affect the risk of infection in general. Further, good general preventive medicine practices, including overall healthcare and proper nutrition, play a role by decreasing the pet's susceptibility to infections.

Fighting antimicrobial resistance isn't easy or clear cut. There is unlikely a single measures that will turn out to be the "magic bullet." To limit the impact of resistant bacteria, we need to take a multifaceted approach, and we need a lot more information to figure out what specific measures should be emphasized.

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The OSPCA has changed their plans for management of the ringworm outbreak that is ongoing in a Newmarket, Ontario shelter. Now, some (hopefully all) remaining animals will be fostered out to local veterinarians while the situation is being brought under control.

One question that has been asked widely in the press and by the public is why these animals haven't simply been sent to foster homes. Particularly now, with all the attention, there would presumably be many people willing to take in these pets. However, putting animals infected or potentially infected with ringworm into foster homes is a controversial and potentially problematic situation, because ringworm can be spread easily to people and other animals in the household. Sending out an animal that is or may be shedding a zoonotic disease is a tricky situation, and one that can't be taken lightly. Additionally, proper management of these animals can take significant time and effort.

A better approach is to send the animals to places where they can be properly, safely and humanely isolated and treated. Veterinary clinics are a logical option, and a request has been sent to clinics in the area to take animals for quarantine and treatment. The reason veterinary clinics are being solicited is that many clinics have the ability to properly house these animals in isolation units and have the expertise and commitment to properly treat them.

Nonetheless, this is no small favour to ask of these veterinary clinics.  Just as taking an infected pet into a household carries some risk, taking these animals into a clinic is also associated with some risk of transmission to people and other animals. However, with proper facilities and protocols, and the donation of sufficient personnel hours to implement those protocols, the risks should be minimal. To facilitate this, we have developed an information sheet with infection control and treatment recommendations for veterinary clinics. For anyone else who is interested, the document can be found here and on the Worms & Germs Resources page under Information Sheets For Veterinarians.

Image: Ringworm lesions on the paws of a dog. Although this is how "classic" lesions tend to appear, clinical signs of ringworm in pets can be highly variable.  (click image for source)

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Never a dull moment...

This morning the Toronto Star published an article about the intended euthanasia of 350 animals at a humane society in Newmarket due to an ongoing ringworm outbreak.  This was quickly followed by another article about the same event that gave a few more details, including some comments from the OSPCA chief executive officer Kate MacDonald, who confirmed that the euthanasias had begun.  A "very aggressive strain" of ringworm and "human error" (related to a breakdown in protocols) are currently being blamed for this morning's actions.  A lot of people are (understandably) very upset.  No one ever wants to see an infectious disease outbreak come to something like this.

I’m hesitant to comment too much at this stage, because we still don’t have all the facts - apparently even the duration of the outbreak is unknown.  No one has said if all 350 animals are infected (or what percentage of them are), nor how many other animals are present at the shelter. We also don’t know what’s already been tried in terms of controlling the outbreak.

A few facts about ringworm (dermatophytosis) that people need to remember:

• Ringworm is a skin infection that can be caused by several species of fungi.  It is not a "worm" at all.  It is also very easily transmitted by direct or indirect contact with infected animals - their fur, their cages, their blankets, or anything else that may be contaminated with infected skin cells or hair.  Such infectious material can even be spread over short distances (e.g. room to room) in dust that is stirred up into the air.
• Ringworm is transmissible to people, so with a large outbreak there are also issues with staff safety, and concerns with adopting out infected animals.  For most people ringworm infection may cause itchy, uncomfortable skin lesions, but for higher-risk people (e.g. very young children, the elderly or immunosuppressed individuals) the infection can be much more serious.
• There are also a lot of animals (particularly cats) that carry ringworm without showing any signs of infection. If the Newmarket shelter has 350 animals with clinical signs of ringworm (a detail about which we have no information right now), that’s pretty bad, but even the animals who don't appear to be infected may be carrying the fungus and could spread it to others.
• Crowding, close contact and warm, humid environments are all factors that increase the risk of ringworm transmission. These are also all factors that are very hard to control in a crowded animal shelter.
• Ringworm is treatable, but it is not cheap or easy. Animals typically require systemic therapy (usually oral medication, which can be very expensive particularly in large dogs) as well as whole-body topical therapy (e.g. dips, shampoos, sprays), and they need to be treated for several weeks. Decontamination of the environment at the same time is critical to prevent reinfection.

Cleaning up a ringworm outbreak at a shelter with at least 350 animals is no small undertaking.  The second article in the Star also describes personnel at the shelter this morning wearing "white hazardous material suits, latex gloves and plastic covers over their shoes", which would be considered reasonable precautions for entering a highly contaminated environment.

I'm sure we'll hear more about this in the days to come, and hopefully that will include more details about why the mass euthanasia was deemed necessary by the OSPCA.

For more more information about ringworm, download the information sheet from the Worms & Germs Resources page, or check out our archives.

Photo source: yorkregion.ontariospca.ca via www.thestar.com

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My parents adopted a cat from their local OSPCA shelter the other day. He's an adult cat (maybe named by now, but not at last report) and he came:

• neutered
• vaccinated against the typical group of feline diseases
• dewormed with fenbendazole
• treated with metronidazole (an antibiotic - it wasn't clear whether this was because he had diarrhea at some point or was diagnosed with something, or whether it was just a routine practice)
• treated with Revolution for flea control

The one thing that's missing from the list is vaccinated against rabies, which I find amazing. Apparently, the cat was given everything they can give at the shelter without the need for a veterinarian. (Presumably the cat came in neutered, because that would hopefully fall under the "need a veterinarian to do it" category. Prescribing an antibiotic would also be something I'd hope would involve a veterinarian.)

Sending cats to new homes without vaccinating them for rabies is bad practice. Rabies is a rare but extremely serious disease. Vaccination is critical, safe and easy. The OSPCA website says that not all shelters vaccinate against rabies. Some shelters have veterinary staff in the facility, so rabies vaccination would be standard there. Other shelters work with local vets to do this, but that's not universal, apparently. I don't see why this isn't a mandatory policy for the OSPCA. Yes, there is a cost to it, but that should be a cost of doing business. Rabies vaccines aren't expensive and many vets would work with groups like this to keep the costs down. Adopting an animal from a shelter isn't cheap, and recovering the small added cost of the vaccine should be possible. I'm not sure whether it really is a question of cost, accessibility or simply not bothering. Getting a veterinarian involved also has benefits beyond just giving the vaccine. Potential health problems can be identified, including diseases that could be transmitted to people that adopt the animals.

It's true that lack of vaccination of adopted pets can be addressed by getting them vaccinated right after adoption. Any pet that has been adopted (or purchased, or otherwise obtained) should be promptly examined by a veterinarian to identify any potential problems, and to make sure the pet is on a proper preventive medicine program. Realistically though, not everyone does this. While you don't like to set policies according to the lowest common denominator, you need to for a deadly disease like rabies when the consequences to people and pets are so high. I find it hard to justify sending any animal out of a shelter without rabies vaccination.

Image source: www.ontariospca.ca

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PetProductNews.com reports that Nature's Variety, a raw pet food company, has unveiled results of a recent "research study" on their products. Whenever you see "research," especially on the web, you need to consider whether it's really valid scientific information or a marketing ploy. This particular case certainly doesn't seem like anything approaching real research.

Apparently the study, commissioned by Nature's Variety, involved the feeding of six adult dogs variations of different diets over a 4.5 month period. They looked at stool quality, volume and odor, blood chemistry, quality of their skin and coat and body weight.

• In research, we worry about sample size. You need to have enough animals to detect any real differences. With 6 dogs, 4.5 months of feeding and different diets, you don't have much of a chance to detect a problem (or a benefit, usually). You could have a diet that kills 10% of the dogs that eat it every year and not detect it in study of that size!
• The number of dogs and time don't even fulfill AAFCO feeding trial requirements, so this doesn't provide any information that would be accepted using standard requirements.

Nature's Variety director of research stated “It’s kind of a sigh of relief.”

• It's pretty concerning that the head of research would be relieved that there were no obvious health problems in such a small study. If they don't have real confidence in the quality of the food, why are they selling it? If you have confidence in your diet, you say "Of course, as expected, our diet was shown to be nutritious and safe..." not "Wow, we're really happy no dogs died!" Research to indicate safety and nutritional value should be done before you sell, not well after.

Duclos said she expects the study to be published in a peer-reviewed journal in about one year.

• Not likely. For one thing, from what they are releasing, it's very weak and not defensible scientifically. For another, they've already released the results. It's inappropriate for people to release results before they've undergone peer review, and releasing data in a press release will probably prevent any reasonable journal from even considering the study.

It's good that Nature's Variety is trying to do some research. It's also good that they're addressing Salmonella contamination following their recent recall. The fact that they are doing something progressive is an encouraging sign. However, they need to do proper research, and make sure it undergoes appropriate scrutiny, instead of using small and relatively useless studies to generate press releases.

Raw feeding has inherent risks of exposure for people and pets to potentially harmful bacteria like Salmonella. Raw feeding can probably be done safely for both the pet and people in some, but not all, situations. More information about raw meat feeding can be found on the Worms & Germs Resources page. 

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When the novel H1N1 influenza pandemic infected large numbers of people, it was not particularly surprising that the occasional infection was noted in pets, considering over 50% of North American households have pets, and the close nature of contact that many people have with their pets. While the few cases that occurred were highly publicized, in the end pet infections were rarely diagnosed (although that doesn't mean they were truly rare), and limited information about these cases has been available. Details regarding one H1N1-infected cat from Iowa (Sponseller et al. 2010) were recently published in Emerging Infectious Diseases.

Here are some of the highlights:

• The 13-year-old cat was an indoor cat that was admitted to Iowa State University's veterinary hospital because of depression, decreased appetite and signs of respiratory disease.
• Two of 3 people in the house had undiagnosed influenza-like illness a few days before the cat got sick. The cat was an affectionate pet and interacted closely with household members.
• Influenza was diagnosed in the cat by detection of H1N1 influenza virus using molecular diagnostic methods (reverse transcriptase PCR) on a sample of fluid collected from the lungs.
• The cat improved with supportive care alone (mainly intravenous fluids to correct dehydration).

Considering the cat lived indoors and people in the house had signs consistent with influenza, it's almost certain that the cat was infected by its owners. This isn't surprising, but it's a good example of how infectious diseases can move between people and pets, in either direction. There's no evidence that pets were a source of human infection, but if something can move from people to pets, there's certainly good reason to think that it could go back from pets to other people. This should be another wake-up call for the need to consider and investigate the potential role of pets in any emerging infectious disease, and to consider emerging "human" diseases in sick animals that might have been exposed.

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Ear mites are a common problem in dogs and cats, particularly in young animals, as well as in strays and animals in shelters. The species of mite typically involved is called Otodectes cynotis. It is transmitted between individuals by direct contact (basically hopping animal to animal, as it does not survive for long in the environment), and causes an extremely itchy ear infection (which can get even worse if there is secondary infection with bacteria or fungi).

There are a few reports of suspected infections with Otodectes in people. Considering how common ear mites are in cats and the small number of reported human infections, transmission between pets and people is probably rare, but it certainly can occur. Most of the reports are somewhat circumstantial, involving people with itchy skin lesions that developed after a pet was diagnosed with ear mites. However, one curious veterinarian took it a step further. 

Dr. Robert Lopez, of Westport, New York, intentionally infested himself with ear mites from infected animals, and described the outcome in a 1993 edition of the Journal of the American Veterinary Medical Association. First, he took a sample from the ear of a cat with ear mites and placed it in his own ear. He described the scratching sounds and movement that he could feel as the mites explored his ear canal. Severe itching developed, to the point where "sleep was impossible." The intensity of the itching and mite movement decreased over time and the infection resolved by itself within a month.

Personally, I think I would have stopped there. (Actually, I wouldn't have made it to that point, but if I did, I certainly wouldn't have tried it again.) Yet, Dr. Lopez wanted to confirm his findings so, a few weeks later, he infected himself again with mites from another cat. The same type of disease developed, although it was less severe and only lasted two weeks.

Guess what he did next - he tried again, wanting to see if the reduction in severity might indicate development of immunity. So, he infected himself a third time, with the outcome being milder disease. This suggested to him (logically so) that immunity to the mites might develop, something that fits with the fact that ear mite infestations are more common in young animals.

Self-experimentation is generally frowned upon, but has been the source of remarkably scientific discoveries, even Nobel Prize winning discoveries (e.g. the role of Helicobacter pylori in gastric ulcers in people). I don't think Dr. Lopez is in line for any prizes, but it shows how a little academic curiosity along with minimal squeamishness can provide some interesting information.

What's the relevance of all this? If your pet has signs of ear mite infestation (e.g. scratching at the ears, dirty material inside the ears), get it examined and treated. If nothing else, this needs to be done because it's a very uncomfortable problem for the pet. There's also some risk of human infection, but it's probably minimal. The mites have to make it from the pet's ear to your body to cause problems. The quicker they are treated, the lower the likelihood of this occurring. Human ear mite infestations, be they in the ear or on the skin, seem to resolve by themselves, with treatment of the animal being the most important part of control. However, it can be a pretty uncomfortable condition and one most people (with the possible exception of Dr. Lopez) would certainly rather avoid.

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I recently attended a meeting to develop antibiotic use guidelines for dogs and cats. One recurring theme during the discussions was our paucity of scientific evidence about how to use antibiotics in certain situations. It's really interesting when you compare antibiotic treatment regimens that are used in humans and standard practices for dogs and cats. Almost invariably, we treat dogs and cats for much longer periods of time than people, even when very similar diseases are compared. Why is this?

One reason is a lack of people doing research and the difficulty performing (and funding) the large clinical trials that are needed to evaluate different treatment protocols. For example, we tend to treat urinary tract infections in dogs for 7-10 days, while in people, just 3 days of treatment is much more common. However, longer treatment courses were used in humans until various research studies showed that shorter treatment was as effective and had fewer side effects. It's likely that we could treat urinary tract infections in dogs for shorter periods of time but we don't have the data to support it at this point.

It's possible that longer treatments for certain conditions are indeed needed in dogs and cats compared to humans. An argument to this effect is that disease in pets can often be more advanced (and therefore potentially harder to treat) when first detected than similar disease in people. For example, if someone has a urinary tract infection, they are probably going to get to their physician quickly. Many owners may not notice the signs of an infection in their pets as early. More established infections may take longer to treat. Does that really happen? We don't know, but it's something we need to know to determine proper treatment durations.

"If it ain't broke, don't fix it". This isn't a very good philosophy when it comes to medicine but it's understandable. If a certain treatment plan usually works, people are hesitant to look at alternatives. The problems with longer term therapy, such as adverse effects of drugs and development of antibiotic resistance, are not necessarily considered (but they need to be).

Bottom line: We need good research to determine optimal treatment protocols for pets. It's very likely that we can greatly decrease the amount of antibiotics that we use while improving patient care, but without good evidence, it's hard to know what to do and where to start. Being too aggressive and dropping treatment times in the absence of evidence may not be a wise decision - too short a treatment period could result in treatment failures and ultimately more sick animals and overall more antibiotic use.

Click image for source.

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I had an advice call recently about the risk of hepatitis C transmission by cat scratches. Hepatitis C is a human virus that can cause serious liver disease. It is most commonly transmitted via the blood of infected individuals. The concern with cats in this case was whether there is a risk of transmission if a cat were to scratch someone with hepatitis C and then scratch someone else.

There are no reported cases of hepatitis C transmission via a cat scratch. For transmission to occur, the following must happen:

• The cat must scratch an infected person who has hepatitis C virus circulating in their bloodstream.
• The scratch must draw blood, which then contaminates the cat's claws.
• The virus must survive on the cat's claws.
• The cat must scratch someone else deep enough to draw blood.
• Hepatitis C virus must go from the cat's claws into the person's bloodstream and survive.

The odds of this sequence happening are very low. It's similar to the concerns about HIV transmission from dog bites - theoretically possible, never proven, and probably of very little concern.

This could be seen as similar to the situation with needlestick injuries in people: someone draws blood from an infected person, and then promptly sticks his or her finger with the needle by accident. Hepatitis C is not efficiently transmitted by needlesticks; only about 1.8% of people that get stuck in this manner (with a needle contaminated with blood from a hepatitis C-positive individual) develop antibodies against the virus. The risk is highest with hollow-bore needles (such as those used for injections and blood sampling) compared to needles used for sutures, because of the greater volume of blood that could be transferred via a hollow-bore needle. Cat scratches are presumably more like surgical needle punctures - there can only be contaminated blood on the outside of the claw, not inside it.

The only time I might have any concern would be if I suffered a significant scratch injury from a cat that had immediately before that caused a major injury in a hepatitis C-positive individual, such as in a situation that might be encountered when two people were breaking up a cat fight, or when someone was trying to pry an attacking cat off another person. It's a very unlikely scenario, and the associated risk would still be extremely low.

Bottom line: Don't worry about hepatitis C when around cats and infected people. Use common sense measures to avoid being scratched at all times.

Image source: www.gooddog.co.uk

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Leprosy usually evokes images of deformed faces and hands and leper colonies. This disease, caused by Mycobacterium leprae, has been recognized for at least 4000 years, and is thought to have been one of the biblical plagues. While now treatable with proper access to healthcare, leprosy is still a problem in some regions.

Feline leprosy is a disease that is present in cats in certain areas of the world, especially British Columbia Canada, northern New Zealand and eastern Australia. It typically causes granulomas (firm fleshy, tumour-like masses) in the skin and tissues directly under the skin, These can become ulcerated and secondary bacterial infections can develop. Feline leprosy has some similarities to human leprosy, however it's not the same thing. It is caused by a related but distinct bacterium Mycobacterium lepraemurium. (It's also suspected that one or more other related bacteria can also cause this disease.) Mycobacterium lepraemurium also causes disease in rodents and can survive in the environment. Cats most likely become infected after being bitten by infected rodents. While the name may be concerning and the disease can be serious in cats, fortunately there is no risk to humans. There is no evidence that this uncommon disease in cats can be transmitted to people.

Image: A photomicrograph of Mycobacterium leprae taken from a leprosy skin lesion. (source: CDC Public Health Image Library ID#2123).

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Campylobacter bacteria are important causes of disease in people. Many Campylobacter species exist, and these different species vary quite a bit in their ability to cause disease in people and animals. Campylobacter jejuni is one of the most common causes of diarrhea in people worldwide, and is most commonly associated with contaminated food.  However, a few studies have reported that having pets (especially pets with diarrhea) is also a risk factor for Campylobacter jejuni infection.

Another Campylobacter species that may be of concern is Campylobacter upsaliensis. This species is primarily associated with dogs and cats, and a large percentage of healthy dogs and cats may be shedding this bacterium in their stool at any time. It doesn't seem to be a cause of disease in dogs and cats, but it may be an important and overlooked cause of disease in people. One study from the US reported that C. upsaliensis was the 2nd most common Campylobacter strain found in people with diarrhea (after C. jejuni). However, the true role of this species is unclear, partly because of common laboratory testing methods. Culture is the main method used to diagnose infection with Campylobacter, but this bacterium can be difficult to grow in the lab. Usually, culture media for Campylobacter contain antibiotics to inhibit other better/faster growing bacteria. Unfortunately, C. upsaliensis is often inhibited by these antibiotics, so it's likely to be missed in these cases even if it is there. Therefore, we might be underestimating the role of this Campylobacter species in diarrhea. This is an critical issue to investigate because C. upsaliensis is so common in dogs and cats, and it's important to determine what role pets play in human disease.

Avoiding Campylobacter infection involves some basic steps: avoid contact with feces, take care when handling diarrhea from pets, wash your hands regularly after handling pets and always wash your hands thoroughly after any contact with feces. Make sure your physician knows you have pets. In particular, if you have a pet with diarrhea or have recently acquired a new pet (especially a puppy or kitten), make sure Campylobacter infection is considered if you get diarrhea. Most infections are mild and go away on their own but some require specific treatment.

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

Image credit: CDC/ Dr. Patricia Fields, Dr. Collette Fitzgerald

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The topic of the potential for feral (stray) animals, particularly cats, to be sources of human influenza infection came up today. For feral animals to be a public health problem, the following sequence has to happen:

Feral animals need to be exposed to H1N1

• This is pretty unlikely. Influenza is spread through close contact, mainly through aerosols generated by an infectious person coughing, sneezing or breathing. Influenza only travels short distances in this manner. The likelihood of a feral animal being exposed to the H1N1 influenza virus is very low because it is rare for a feral animal to get that close to people. If there is close contact, it's probably very short term, and not high risk for exposure.

They need to become infected AND shed appreciable levels of virus

• Considering the number of infected people, how common pet cats are, and the fact that only one cat has been diagnosed with H1N1, the risk of actually transmitting the virus to a cat is very low even with close contact with an infected person. If tens of thousands of household pet cats have had close and prolonged exposure and only one infection has been diagnosed, this virus is pretty poorly transmissible to cats.

They need to be exposed to susceptible people

• As discussed above, there's not too much contact between stray cats and people. Close and prolonged contact is extremely rare. Influenza is only shed by infected individuals for a short period of time, unlike some other infections. So, the chance of an infected cat having close contact with a person during the relatively short infectious period is very low.

Each one of these events independently is very unlikely. When you combine them, it should be clear that the risks posed by feral cats are extremely low (probably about as close to zero as we get with infectious diseases).

A bigger concern might be someone infecting their indoor/outdoor cat, who would then infect a stray cat, which would then infect another indoor/outdoor cat, which could infect a family member. That's still a VERY unlikely situation - really it's nothing to worry about.

There are certainly public health issues with feral cats. H1N1 is not one of them.

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One of the common questions accompanying the onslaught of calls I've taken today is "How do you diagnose influenza in pets?"

Clinical signs, such as sneezing, coughing, fever and lethargy, are not useful for diagnosis. Influenza can produce highly variable disease, ranging from almost none to very severe - so you can't look at an animal and say it has influenza just based on the clinical signs. We don't know much about H1N1 influenza in different animal species (including pets), but this type of influenza can probably cause a wide range of disease in animals as well (at least in those it can infect).

The presence of someone in the household with influenza should get you thinking about flu in a sick pet, but it is far from diagnostic. Many, many people have influenza, but very few pets do. There are many other diseases that can produce signs similar to influenza in pets. The health of people in the household is an important thing to know, but we can't jump to conclusions based on the household history alone.

Laboratory testing is required for the diagnosis of influenza, and there are a few options:

• PCR testing of nasopharyngeal (throat) or nasal swabs, or fluid collected from the trachea: This molecular test detects influenza virus RNA. This is the fastest test and it is most sensitive when samples are taken early in disease. This is the main option for diagnosis at this time.
• Serology: This involves testing blood for antibodies against influenza. Two samples are taken 10-14 days apart. If the antibody level rises 4-fold or greater, that is indicative of influenza infection. This is considered the most reliable method of diagnosis of influenza in many species but takes time. It is not currently a viable option for pets because tests for pets are not available.
• Virus isolation from nasopharyngeal or nasal swabs, or tracheal fluid: Samples are inoculated into eggs to try to grow the virus. This can take quite a while and isolation of the virus can be difficult. This is a method used by specialized labs with laboratory containment conditions appropriate for this virus and may not be readily available.

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The recent discovery of H1N1 influenza in a pet ferret has led to another round of concern about the potential impact of H1N1 on pets and pets as a source of human infection. Finding H1N1 in a ferret is not particularly surprising, considering ferrets are susceptible to various (including human) influenza viruses. We shouldn't dismiss the potential that certain pets could become infected by this virus or transmit, it but the overall risks are presumed to be very low. There have obviously been many, many cases of H1N1 influenza in pet owners, yet there is just this one report in a pet (although it's certainly possible that other pets have been infected but not diagnosed). Ferrets may be the biggest concern. Pet birds and pot-bellied pigs may also be at higher risk considering this virus can clearly infect pigs and birds. Cats are probably a bigger concern than dogs because of what we know about cats' susceptibility to (and ability to shed) H5N1 (avian) influenza.

The risks are low to pets and pet owners, but there's rarely a no-risk situation with infectious diseases. A few basic measures should be taken to reduce the risks associated with this pandemic virus:

• If you have (or think you may have) influenza, treat you pet like other people in your family. Avoid contact with them, especially their faces, and pay close attention to hygiene (especially handwashing). This should help reduce the risk of exposing your pet to H1N1.
• If you have influenza, or your pet has been exposed to anyone with influenza, and your pet becomes ill (e.g. respiratory disease, fever, lethargy), contact your veterinarian. Avoid close contact with your sick pet (especially the face) and wash your hands after you handle it.
• Relax and enjoy the company of your pet. The risks of influenza are low.

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I was talking with a colleague the other day and somehow norovirus came up. He explained how once, his wife had viral gastroenteritis and ended up vomiting on their cat. Weirdly enough, his wife told my wife the same story (they work together). My wife got a better version of the story which included a nice image of her chasing the cat around the house in her sickened state because the cat was splattering vomit all over the place. (Yuck!)

Anyway, beyond being an entertaining story (as long as it's not you doing the puking and chasing), it raises the question: if you've turned your cat into a biohazardous (and stinky) norovirus vector, what do you do to clean it up?

Dogs and cats cannot become infected with norovirus. However, they could potentially act as a source of infection for people if their coats are contaminated with the pathogen. Usually, I think about this in the context of someone having a little contamination of their hands and subsequently touching a pet (not a vomit-soaked animal, although evidently that can happen too).

So, what should you do? I don't really know. The CDC recommends using bleach or another approved disinfectant on contaminated surfaces, but that's obviously not an option for a cat. Heating contaminated objects to 60C is another recommendation, but again, not for a live animal.

I guess giving the cat a bath would be a good start, and it would presumably greatly reduce the amount of norovirus on the coat. However, if you have viral gastroenteritis already you're probably not in much of a state to do that. Another family member that is not flat-out sick in bed could do the job. However, anyone bathing a heavily contaminated animal should wear a mask and gloves, change their clothes after, clean any surfaced that get contaminated in the process with bleach or another disinfectant, and (of course) wash their hands. Unfortunately, I suspect if you had to bath a cat covered in norovirus that you would probably end up getting infected, either from the cat or the contaminated environment. Leaving the animal covered in vomit is not a good alternative either, since it would continue to contaminate the household as well as look and smell really bad. We don't know how long norovirus can survive on an animal's coat, but it's reasonable to suspect that it could survive a couple of days. Keeping the pet away from uninfected individuals for a week or so wouldn't be a bad idea.

The easiest way to handle this is to avoid vomiting on your pets.

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As public awareness of zoonotic diseases increases, some new marketing opportunities are created. One is offering screening of pets for "protection" of the family. One company, Healthgene, offers a Family Protection Program that involves screening pets for selected zoonotic pathogens. Unfortunately, it involves the use of non-validated PCR tests for pathogens for which screening of healthy animals is not considered useful. They make various unsupported, illogical and sometimes downright incorrect statements such as "If, by chance, any positive results should occur, not only should the animal be treated immediately, but the client and anyone having contact with the animal should also notify their family physician." Despite the fact that the tests themselves are of questionable quality and the results are essentially useless, I'm sure they are developing a market.

Also, it's pretty concerning that this company misspells the names of various microoganisms for which they test on their website - they even misspell "protection" in one of their Family Protection Plan info sheets! Inability to spell isn't necessarily linked to inability to test properly, but it shows a lack of care and attention to detail that raises further red flags in my mind.

Zoonotic diseases ARE a concern. We need to pay attention to them and try to reduce the risks of transmission to people. Screening healthy animals is almost never a component of this. Save your money when it comes to "routine" screening of healthy animals - talking to your vet about potential problems and washing your hands are much better ways to reduce the risk of infection.

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When it comes to methicillin-resistant staphylococci in pets, MRSA (methicillin-resistant S. aureus) gets most of the attention. That's fair since it's emerging as an important health problem, and can be transmitted between pets and people. Now another staph, MRSP (methicillin-resistant S. pseudintermedius) is getting more attention, and it's actually a more common cause of infections in dogs and cats compared to MRSA. There are also some other methicillin-resistant staph that get much less attention. One is methicillin-resistant S. scheliferi (MRSS).

There are actually two different subspecies of this bacterium, S. schleiferi subsp. coagulans and S. schleiferi subsp. schleiferi. Staphylococcus schlieferi subsp. coagulans is the coagulase-positive subspecies. (Coagulase testing is one of the main ways staph species are classified.) Sta[hylocccus schleiferi subsp. schleiferi is coagulase-negative. In general, coagulase-negative staph are considered to be minor concerns and rare causes of disease other than in sick, compromised individuals in hospitals. However, it looks like S. schleiferi subsp. schleiferi is an exception to that rule, as it is able to cause disease in otherwise healthy dogs and cats.

Both S. schleiferi subtypes predominantly cause skin and ear infections. As with other staph, methicillin-resistance is a concern and is increasing. Methicillin-resistant S. schleiferi (MRSS) rates appear to be increasing, which is a concern because methicillin-resistant staph infections are harder to treat due to their resistance to many antibiotics.

One factor that limits our knowledge of the role of MRSS (and really, S. schleiferi in general) in disease is the fact that many, if not most, diagnostic laboratories don't try to differentiate it from S. pseudintermedius because the two species are very similar. (Sometimes, labs don't even try to differentiate any of the coagulase positive staph, including S. aureus).

While MRSA in pets is a public health concern, there is probably much less to fear from MRSS. Staphylococcus schleiferi infections in people are quite rare and there is currently no indication that pets are an important source of human infection. However, given our limited knowledge of this bacterium, it's wise to take some degree of precaution around animals with MRSS infections, particularly basic measures such as avoiding direct and indirect contact with infected sites, and good handwashing habits. These are the same general recommendations for pets with MRSP, and more details about this are available on the Worms & Germs Resources page. 

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Methicillin-resistant Staphylococcus aureus (MRSA) infections are an emerging problem in dogs and cats. They're a huge problem in human medicine, and the emergence of MRSA in pets can be directly traced to the spread of MRSA in people.

A big problem with MRSA infections is that they can be difficult to treat because they can be resistant to many antibiotics (not just methicillin). This complicates treatment, but it's important to remember that most MRSA infections are treatable.

An important concern with MRSA is that it may lead to unnecessary veterinary use of drugs that are critically important for treatment of life-threatening infection in humans. Vancomycin is an antibiotic that is occasionally used to treat MRSA infections in dogs, although I've never had to use it. I stumbled across a supposed "veterinary information website" today that stated vancomycin is the main treatment for MRSA in dogs. It quickly became clear the authors had no clue about the topic, because they kept calling MRSA a virus (always scrutinize the source of information, especially on the internet). Information like this doesn't help with prudent use of drugs like vancomycin.  It's important for pet owners and veterinarians alike to realize that these "big-gun" antibiotics (such as vancomycin) are rarely needed for MRSA infections in dogs and cats. There are almost always other, and usually better, options.

Vancomycin is also sometimes inappropriately used in animals, which can lead to worsening of infection.  For example, if vancomycin is mistakenly given orally, the drug is not absorbed from the intestinal tract and therefore has no chance of fighting infection elsewhere on the body.

In general, MRSA infections are quite treatable. Survival rates tend to be high and, with proper treatment, should be no lower for MRSA infections versus infections caused by susceptible strains of S. aureus. A comparison of MRSA versus susceptible S. aureus infections presented last year reported no difference in survival rates, with an overall survival rate of >80%. The key is diagnosing the infection early and getting started on the right treatment. That means getting cultures done earlier, rather than later.

While increasing antibiotic resistance may lead to more need for "big-gun" antibiotics in some cases, we need to act prudently and restrict their use to situations in which they are absolutely required. Use in animals needs to be very prudent to avoid contributing to antibiotic resistance in people. Inappropriate use in animals could lead to more calls to restrict veterinary access to various drugs, which could threaten treatment of other animals with other types of infections.

Don't confuse "big-gun" antibiotics with the best treatment.

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

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Skin and soft tissue infections increasingly caused by highly drug-resistant bacteria, along with various concerns about antibiotic use, have led to a desire to find non-antibiotic approaches to treatment of these infections. Tea tree oil has some potent antibacterial properties when tested in the lab, and there are some studies indicating it might be effective for the treatment of certain infections. Some work that we've done in my lab shows promising activity of a few different essential oils against MRSP.  Some of these oil may be similarly useful treatments for certain infections. 

However, as I've stated before, we need to make sure that we adequately investigate safety of any new drug or therapy. All natural does not mean safer. If something kills bacteria, we need to make sure that it doesn't also harm an animal's cells and tissues.

Tea tree oil can cause damage to skin and soft tissue cells, but it's unclear whether this is really a problem during short courses of treatment. Nonetheless, in humans it has been recommended that tea tree oil not be used for treatment of burns because of concerns about tissue damage.(Faoagali et al, Burns 1997)

Another concern is toxicity from ingestion. This isn't usually a concern in adults, but there are a couple reports of children that became seriously ill (neurological abnormalities, progressive unresponsiveness... fortunately temporary) after ingestion of small volumes of tea tree oil. This leads me to have concerns about ingestion of the oil by dogs and cats if they lick areas where it has been applied, or eat bandages soaked in oil. They probably wouldn't ingest that much, but it's possible.

At this point, the jury is still out on the usefulness of tea tree oil. There are some potentially beneficial aspects and some safety issues that need to be clarified. In the interim, if you want to use tea tree oil:

• Recognize it's not a proven therapy. Don't use it in place of conventional treatment recommended by your vet.
• Keep it out of the reach of children and pets.
• Be judicious about the amount you use, and make sure pets don't lick it off.
• If the infected site seems to get worse after tea tree oil is used, stop applying it and see your veterinarian.

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Animal bites are very common. Millions of people are bitten every year, and the resulting burden in terms of pain, infection and financial costs is astounding. Dog bites get the most press because they often cause significant trauma. Dogs have larger and stronger mouths, and can bite repeatedly and more aggressively in some attacks. Deaths attributed directly to pet bites pretty much exclusively involve dogs.

Cat bites are smaller and have less chance of causing significant injury to tissues, but they may be more severe in the long run. There's a scientific paper called "Cat bite infections: biological warfare amongst cats," which is a testament to the nasty populations of bacteria that live in cats' mouths. It's not just the presence of bacteria that's a problem (afterall, dogs' mouths are full of potentially nasty bacteria as well) - the nature of cat teeth and the resulting bite wounds is a major factor. Cat bites often result in small but deep puncture wounds. This pushes bacteria deep into the tissues, where they're harder to get rid of and which results in a much greater chance of causing an infection. Furthermore, cats tend to bite areas that are high risk for development of bad infections, especially hands, which have a complex and susceptible network of tendons, tendon sheaths, joints and nerves. Bites that appear to be minor can end up causing serious problems, often much worse that an initially more dramatic dog bite.

Really, you don't want to be bitten by either a dog or a cat (or an iguana, hamster, person or anything else). A large percentage of bites are avoidable, and knowing how to interact with animals and read signals of aggression or fear are critical. If you are bitten, prompt and proper care of bites is required to prevent serious, long-term complications.

More information on bites, including management of bites, is available on the Worms & Germs Resources page. The CDC has a podcast that includes information about bite-avoidance that can be accessed by clicking here.

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A house cat in the Eagle, Colorado area has been diagnosed with pneumonic plague. Plague, caused by the bacterium Yersinia pestis, is a disease that still strikes fear into people. While we are long since removed from the period where the "black death" killed a large percentage of the population in Europe, plague still has a foothold is some regions of the world like the southwestern US. It is present in some wildlife (mainly rodents) and periodically infects people or domestic animals through transmission by infected fleas or direct contact.

Plague is periodically identified in cats - it's almost always outdoor cats that are affected since they have more interaction with wildlife and are at greater risk of flea infestation. Several forms of the disease can occur, including pneumonic, septicemic and bubonic plague. Pneumonic plague is a severe lung infection caused by the plague bacterium which is highly fatal.  This form is of particular concern because infected cats can spread the infection to people through aerosols produced by coughing and sneezing, or through contact with respiratory secretions. People caring for sick cats are at risk of developing plague (especially pneumonic plague, which is almost invariably fatal if untreated). Veterinary personnel are at particularly high risk. One study reported that 20% of people who contracted plague from cats worked in vet clinics. Of these, 25% of them died. 

If you live in an area where plague is present in wildlife, keep your cat indoors, avoid contact with wild rodents, keep wild rodents out of your house and make sure that you have a flea prevention program for you pets. If these things are done, the risk of disease transmission is very low.

Image source: www.northernsun.com

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I received a flyer from Zoologix, a company that offers various (typically unvalidated and unproven) PCR tests for animals. The flyer headline was "Pets can carry MRSA - but testing can help."

Testing in certain situations is useful, but this is almost always limited to diagnosis of animals with active infections (i.e. they're sick). PCR is not a good way to make such a diagnosis, because the test doesn't tell you anything about the bacterium's susceptibility to other antibiotics. Screening of pets just to determine whether or not they carry MRSA is rarely needed, and currently there is no evidence that PCR is a reasonable test for this.

There are no validated PCR tests for MRSA in animals. We looked at using a human test in horses and it failed miserably. There are validated tests for use in people, and they are quite good: they accurately identify MRSA and differentiate it from other methicillin-resistant staphylococci and from methicillin-susceptible S. aureus. That's critical, because you have to know what a positive test really means.

I called the company and asked what the test actually detects. They said it detects the mecA gene, the gene that confers methicillin-resistance to staphylococci such as S. aureus. However, this gene can be present in other staphylococci that can be found in many  healthy dogs and cats (10-30% in some studies). It does not actually detect MRSA and a large percentage of samples that give positive results will be false positives. The tests that are used in humans are specifically designed to look at two things in combination: whether S. aureus is present and whether it has the mecA gene (methicillin-resistance). This is the right approach because it excludes all those other false positives. Detecting mecA alone is completely useless. It's interesting that the flyer states "PCR testing is fast, effective and accurately differentiates MRSA from other bacteria - even other Staph strains." Based on what the company told me over the phone, with regard to the test they're advertising, that's a blatant lie.

This is an example of a combination of bad science and bad ethics. This company has no business marketing this test. It's false advertising, because the test isn't an MRSA test. Their justification for using it is similarly weak. Anyone thinking about using this test should run away quickly! The issues with this test (and others) should also be considered when deciding whether to use this company for any tests.

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

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In an interview with the San Francisco Chronicle, veterinary dermatologist Dr. George Doering makes a pretty obvious but very important comment that is worth repeating:

"The biggest problem we have in almost all the fields of veterinary medicine is compliance. You say to a client, "This dog needs to take this antibiotic twice a day." Well, the reality is we might be lucky if they get it once a day. ...They don't want to accept the seriousness of the problem."

This very true and very important. Compliance with recommended antibiotic therapy is probably a major factor in treatment failure, recurrent infection and antibiotic resistance. Antibiotic dosing regimens are specifically designed to ensure that the right concentration of drug is present in the body for the appropriate time. Missing doses, skipping days, not making sure the animal actually ingests the drug, and other problems that result in the pet not getting what is was supposed to get are very important.

It's easy to understand why this happens, because administering antibiotics (particularly to some difficult-to-pill dogs and cats who can smell the medication when it comes in the house!) can be a hassle. Because of this (and the very natural human tendency to take the easy way out), it's really important for people to understand the concerns about inadequate antibiotic administration and what they need to do.

• Follow the entire treatment course. You should have no antibiotic left at the end of the recommended treatment time.
• Make sure your pet actually swallows the antibiotic. If you add pills to food, make sure you check to see that the pill isn't left behind. It's amazing how animals can eat a big bowl of food and leave behind a little pill. The picture shows how my dog Meg can, in the process of inhaling her food at an incredible rate, leave behind a tiny ephedrine pill.
• If your pet will not eat the drug voluntarily, talk to your vet about other ways to administer it, such as compounded in chewable treats. Depending on you and your pet, opening your pet's mouth and placing the pill at the back of the tongue may be an option. Talk to your vet about this first and make sure you wash your hands after. If you think there is a risk you might be bitten, if you are at high-risk for infection because you are immunocompromised, elderly or pregnant, don't try to "pill" an animal in this manner.
• If you still can't get the drug into your pet, talk to your vet right away.  If you wait a couple of days or a week or more to tell your vet, your pet may be even sicker by then. There may be other options to oral drugs such as injectable antibiotics. This might end up being more expensive or difficult (e.g. you may have to take your pet to the vet every day for its medication), but it will be better for your pet and may even save you money in the long run by ensuring the infection is properly and completely treated the first time.
• Never stop treatment because your pet looks better. Often, signs of infection get better before the bacterium is completely eliminated. Stopping too soon allows the bacterium to regrow, potentially as a more resistant form.
• If you are supposed to take your pet to the vet for a recheck at the end of treatment, then do so. Sometimes longer courses of antibiotics may be needed, and it's much better to continue the current treatment course than to have to start again a couple weeks down the road when the infection has returned (sometimes with a vengeance).
• If in doubt about anything, call your veterinarian.  He or she is there to help, and wants your pet to get the best treatment possible.

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I was reading an interesting old paper the other day about Q-fever in cats. Q-fever is a zoonotic disease caused by Coxiella burnetii. It is most commonly associated with contact with sheep, cattle and to a lesser extent goats, around the time they give birth. This bacterium is highly infectious - it only takes a small number of bacteria to cause disease. (That's one of the reasons it's classified as an important bioterrorism agent).

While most of the focus in on ruminants, there have also been many reports of Q-fever associated with cats, also mainly through contact with these animals around the time they give birth.  Cats may be the most important Q-fever reservoir in urban areas.

The study I was reading, a 1988 article from the journal Chest, describes a Q-fever outbreak in a town in Nova Scotia. Thirty-three people were infected in the town of Baddeck (population 900, meaning 2.8% of the population was affected). Forty-two percent of infected individuals lived in four side-by-side buildings. Investigation revealed that most infected people had contact with a cat that have given birth to stillborn kittens (stillbirths are common in cats infected with Coxiella). The cat lived in one of the four buildings and regularly visited neighbouring buildings.

This is just one of many reports of Q-fever associated with cats. Almost all involve direct contact or being in the vicinity of cats around the time of birth. Since this bacterium is so infectious, and can even be spread through the air through aerosols (e.g.dust, tiny droplets of fluid), direct contact (e.g actually touching the cat) is not required for infection to occur.

That being said, cat-associated Q-fever is probably still pretty uncommon, but Q-fever can be a very serious disease. Since transmission mostly involves cats at the time of birthing, a few basic measures should be able to greatly reduce the risks:

• Avoid contact with cats that are giving birth or who have done so recently.
• Avoid contact with newborn kittens and areas contaminated during the birthing process.
• If your cat is going to give birth, try to have it do so in a well-ventilated area away from areas where people spend time and away from areas where food is prepared.
• If contact with the mother cat, kittens or areas/items contamination with birth fluids is likely to occur, gloves should be worn. Hands should be washed after gloves are removed.
• If a cat gives birth inside, the area should be thoroughly cleaned and disinfected afterwards. Gloves should be worn for this.
• The risks are probably higher with stray cats (who are more likely to be infected), so extra care should be taken to avoid contact with stray cats around the time of birth.

More information about Q-fever can be found in the Worms & Germs archives.

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There are two situations when animals may be quarantined because of rabies concerns:

1. After biting a person.
2. After potentially being exposed to a rabid animal.

The time frame for quarantine in these two situations is quite different because of what the quarantine is meant to accomplish.

Animals that have bitten someone are quarantined for 10 days under observation to see if they develop signs of rabies. Most animals that bite do not have rabies, and this is the easiest way of determining whether the animal could have potentially transmitted rabies by way of the bite. If an animal was rabid and infectious at the time of biting, it would die from the disease within 10 days. Animals can only transmit rabies virus after it has reached the brain and started to spread outwards via nerves - it gets into saliva by working its way down nerves from the brain to the salivary glands. Once an animal gets to that stage of disease, they die quickly. So, if the animal is still alive after 10 days, it was not rabid at the time of the bite. Quarantine is important so that it can be clearly proven one way or the other whether the animal was rabid. If the biting animal was not quarantined and ran away, the recommendation would be to err on the side of caution and treat anyone bitten as if they'd been exposed... but we want to avoid that if at all possible.

The second type of quarantine (for a potentially exposed animal) is based on less solid evidence. The idea in these cases is to keep the potentially exposed animal isolated while waiting to see if it develops signs of rabies, because there is no other reliable test for rabies in a live animal. For example, if an unvaccinated dog gets into a fight with a rabid raccoon, it would be considered potentially exposed. It would be quarantined (or immediately euthanized... the other option) and monitored to see if it develops signs of rabies. The length of quarantine for non-vaccinated dogs is usually 6 months, but this may vary by region. This helps reduce further rabies transmission by ensuring that a dog that develops rabies during the quarantine period is not roaming at large and able to infect people or other animals. One weakness of this approach is the incubation period of rabies, which can be very long. There is not a lot of objective research on which to base the 6 month time frame (unlike the 10 day quarantine described above). After 6 months, it's very unlikely the dog will develop rabies, but we can never say it's 100% because of the rare cases of rabies in humans with extremely long incubation periods. In reality, it's likely that the vast majority of animals that are exposed will develop rabies before 6 months, so it's a reasonable time frame. Would it be better to use 4 or 8 months, or something else? Possibly, we just don't know.

The easiest ways to avoid hassles associated with rabies quarantine are:

• Prevent bites. If your pet is trained and observed properly, it's unlikely to bite anyone, so the 10-day post-bite quarantine shouldn't be an issue.
• Vaccinate your pet. Properly vaccinated pets are not subject to the same long, strict quarantine (although a shorter period of isolation (often at home) is usually still required).

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

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A paper in the Journal of Clinical Microbiology back in 2000 described a case of Pasteurella multocida meningitis in a one-month-old baby that was linked to a pet cat. Pasteurella multocida is a bacterium that can be commonly found in the mouth of healthy dogs and cats - 90% or more of healthy cats may have it in their mouth. The organism can cause infection in humans.  These cases are usually associated with close contact with animals, such as bites, scratches and licking wounds. In this case, there was reportedly little contact between the baby and the cat, yet the same P. multocida strain was found in both. The cat was healthy and the bacterium was found in its mouth. There was no clear route of transmission (like a bite or a scratch), however unidentified contact with the cat or (more likely) indirect transmission of the bacterium from the cat to the baby by another person are possible.

This is a good example of the unpredictable nature of zoonotic infections. There was no reported underlying disease that made this baby more susceptible to infection. It's just that being very young (or very old, or immunocompromised) means you're more likely to develop infections from the myriad bacteria that are present all around us. While this infection might not have been preventable, we need to think about good routine precautions involving contact of pets with babies.

• Keep them apart (but not completely). Pets should not be allowed to lick or have other close contact with a young baby. That being said, household pets need to be around the baby to learn to interact with the child safely, and recognize the baby as a member of the family, but supervision is needed and direct contact should be avoided.
• Good hygiene should be used around pets and babies (individually and together). Hands are the main source of disease transmission and regular hand washing is a great infection control tool.

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A recent study from the Netherlands investigated the prevalence of zoonotic parasites in pet feces and on pets' haircoats. The authors sampled feces and fur from dogs and cats, and looked for Toxocara (roundworms), Toxoplasma, Giardia and Cryptosporidium. All these parasites are of concern from a public health standpoint because they can be found in healthy pets and can also infect people.

Toxocara eggs were found on the haircoats of 12% of dogs and 3.4% of cats. Levels were low, ranging from 1-31 eggs per sample. An important aspect of this study was that they also assessed viability of these eggs, and found that none were viable.  Therefore, even though eggs were present, they were not relevant because they were dead. Exposure to UV light and lack of humiditiy were cited as possible reasons for the death of the eggs.

Toxocara were found in the feces of 4.4% of dogs and 4.6% of cats, which is consistent with other studies of healthy pets.

Toxoplasma was not found in the feces of any cat. (Cats are the hosts for this parasite so dogs weren't tested.)

Giardia was found in the feces of 15% of dogs and 13.6% of cats. However, when these strains were typed, the vast majority were species-specific types that do not cause disease in people. Only 2 of the 15 Giardia samples were assemblage A, a type that is transmissible from pets to people. This is very important to know because crude Giardia numbers don't tell you the whole story. 

Cryptosporidium was found in feces of 8.7% of dogs and 4.6% of cats. However, they were not able to type these parasites to determine if they were species that typically cause infection in humans, or whether they were Cryptosporidium felis or C. canis, which rarely cause disease in people.

The discussion section of the paper contains an interesting and relevant point about exposure to Toxocara eggs on the haircoat of pets. The authors state "Even in the worst case scenario of highly contaminated fur, e.g. with the highest Toxocara [eggs per gram] of 300 and an embryonated rate of 4% from the study of Wolfe and Wright, it is necessary to ingest more than 4 grams of hair, with 12 embryonated eggs per gram, to ingest 50 infective eggs."  Based on these data, exposure to parasites from the haircoat of pets is quite unlikely.  It might be a greater concern with stray or debilitated animals, or with puppies/kittens, who could have much greater coat contamination.

The take home message: Normal contact with healthy pets likely poses minimal risk of transmission of zoonotic parasites. That being said, regularly washing your hands is still a good idea because of the potential for exposure to other types of microorganisms (e.g. bacteria), and in rare circumstances where there may be large parasite burdens on a pet. Good deworming practices, particularly for puppies and kittens, also need to be considered.

Reference: Overgaauw et al, Veterinary Parasitology, 2009.

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Canadian Guidelines for the Treatment of Parasites in Dogs and Cats have recently been released. These guidelines were developed by an expert panel, consisting of six Canadian veterinary parasitologists and two private practitioners. They provide a good, balanced approach to the treatment of parasites, with an emphasis on the risks present in different regions and in different types of pets. There is very little objective information on which to base some of the recommendations, so many aspects are instead based on expert opinion, not necessarily hard facts, but when data are lacking, that's when opinions from independent experts are most needed. The guidelines provide an overview of recommended treatments along with an explanation of the reasoning.  This document is a useful resource for pet owners and veterinarians alike. There is also discussion about why guidelines in Canada differ from those in the US. To download these guidelines click here.

Note: Development of the guidelines was supported by a pharmaceutical company, but the information they contain was developed by the independent experts mentioned above.

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Recently, I wrote a post about the need for vets and physicians to communicate more, and about concerns that zoonotic diseases get missed because vets deal with animals and physicians deal with people, but few people pay attention to the interface between them. A reader (my father, actually) wrote this comment.

“...is the opposite also true? If I take my sick cat to the local vet, will he advise me to see my physician if I begin to feel ill effects? Are vets trained to know that pets can transfer disease to their owners or in this an emerging part of vet. science?”

It’s a good question and one that doesn’t have a straightforward answer. Vets certainly do get educated regarding zoonoses.  From what I understand from talking to colleagues in the human medical field, there is much more emphasis on zoonoses in the veterinary medical curriculum compared to the human medical curriculum. However, a lot of the focus is on foodborne and waterborne zoonoses, with much less information about companion animal (e.g. dog, cat, horse) zoonoses. Different vets have quite variable knowledge in this area, ranging from excellent to poor. It’s a huge field (I’m still learning more about it all the time), and vets and physicians alike have busy schedules and many other areas where they need to stay current as well, so it’s not unfathomable that zoonoses could get neglected.

So, to answer the question, if you take your sick cat to the vet, it’s unlikely he/she will initially ask about your health. However, if the vet suspects a zoonotic disease, hopefully he/she would tell you what it is and possibly what signs for which to watch out. Providing additional information would also be useful, which is why we're developing the information sheets that are available on our Resources page). At that point, the vet would typically (and reasonably) leave it up to you to determine whether you should see your physician and what should happen from there. In the grand scheme of things, it would be very useful for vets and physicians to have some form of dialogue or at least an understanding of each other's roles and a willingness to call each other when appropriate.

Both human and veterinary medicine have a long way to go to get to the "one medicine" concept that people like to talk about. I think we’re slowly moving in the right direction, but vets and physicians need to talk more to properly cover this important area of overlap between their professions.

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A few years ago, I wrote a commentary in the journal Emerging Infectious Diseases about pets and household quarantine. It was written after SARS (severe acute respiratory syndrome) had caused tremendous problems in many areas, including Toronto. The point I was trying get across was that while there was a strict household quarantine implemented for exposed people, there was no consideration of pets. We now know that cats can become infected with the SARS coronavirus, and can transmit it to other cats. However, when people were quarantined, there were no recommendations for pets - pets could interact with quarantined people, then visit non-quarantined family members, or interact with other animals or people outside. From my standpoint, this was a significant concern.  If cats had become infected with SARS, they could have been a source of transmission in households and potentially beyond. If SARS had infected the feral cat population in Toronto, it might have been very difficult to eliminate. I encouraged groups to ensure that pets are included in household quarantine guidelines.

The topic is front and centre again with swine flu. We don't know whether dogs and cats can be infected with this particular swine flu virus, but we DO know that cats can become infected with H5N1 avian flu and shed the virus. In my mind, that means that we should consider pets susceptible until proven otherwise.

So what should we do if people are being quarantined?

• If you are quarantining the family, quarantine the WHOLE family, including pets.
• Quarantined cats must be kept in the house. Quarantined dogs must be kept in the house as much as possible. They should only be taken outside to urinate/defecate, and this should be in a "remote" area where they can't have contact with other people or animals. They should always be under physical control (e.g. on a leash) when outside.
• If a quarantined pet gets sick, a veterinarian should be called first. That way, it can be determined if the pet needs to be examined, and if so, the clinic can know when it's coming and have protocols set up to handle it with infection control precautions.

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Recently, I made a few comments about climate change and the potential impact on infectious diseases in horses on our sister site, equIDblog. A recent news article in New Scientist discussed concerns about climate change and pets. The main infectious disease concern regarding climate change is changes in patterns and spread of insect-borne diseases, because different insect vectors may expand their normal ranges or change their seasonality in response to climate change. Some of the examples cited in the article include:

• Babesiosis, a blood-borne disease spread by the European dog tick, is being found in areas of Europe where it was previously rare.
• Increasing populations and ranges of ticks have been reported in many countries, which is a significant concern based on the number of different diseases these ticks can carry and transmit.
• Leishmaniasis has been identified in dogs in the southern UK.  If climate change allows sandflies (the insect vector of this disease) to become established in the UK, then spread of this disease could become a major problem.
• Milder winters may result in longer periods of activity of some insects that transmit disease, thereby extending the times of the year when there is a risk of disease. In some areas, year-round risk could develop for diseases that were previously seasonal.

Climate change is a complex and still rather controversial topic. Predicting the infectious diseases implications of climate change is difficult.  Information that is already available for some diseases, combined with general knowledge about microorganisms and their hosts, can help us make some educated guesses about what may happen. While the full scope of the impact cannot be predicted, it is almost certan that climate change will result in infectious disease challenges in both veterinary and human medicine.

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Quarantining animals that have potentially been exposed to rabies is a standard practice, but quarantining a whole town is new to me. Because of a large increase in rabies cases in the Flagstaff, Arizona area, a rabies quarantine was established on April 8th by the Coconino County Board of Supervisors. The quarantine requires all dogs and cats to be enclosed or secured on their owner's property. When off the property, animals must be on a leash that is no longer than six feet in length. All dogs and cats must be vaccinated, and low-cost rabies vaccine clinics have been held to help increase compliance with this requirement. Vaccination of wildlife using baits containing an oral form of rabies vaccine will also be performed. The quarantine also restricts feeding and interacting with wildlife. Also, people cannot leave pet food outside after sunset and all compost piles must be completely enclosed.

This is an aggressive approach to rabies control in an area experiencing a wildlife outbreak of the disease. They've implemented comprehensive but still quite practical measures that should help reduce the risk of exposure of domestic animals (and people) without a significant negative impact on pet owners. I've mentioned my concerns about rabies vaccine clinics in the past, but this is a situation where I think it's a good idea.

It's always hard to evaluate the effectiveness of outbreak measures, because you never know what would have happened if nothing had been done. Regardless, it will be interesting to see how well this quarantine works, both in terms of the number of new rabies cases they see and the response of citizens to these restrictions. It would be very useful if Coconino County personnel provide information about how things went when the quarantine is over - the information might be useful for management of future rabies outbreaks.

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Over 50% of households in Canada and the US have pets, and the numbers are probably similar in many other countries. Pets are often considered part of the family socially but we need to consider them part of the family biologically as well. It's clear that diseases that be transmitted between people and pets - in both directions. Unfortunately, it's also clear that physicians and vets don't do a very good job talking to each other.

Pet contact (and animal contact, in general) should be part of the standard history obtained by any physician.  In my perfect world, every medical record would include a permanent record of contact with pets or other animals. This information is potentially useful because certain diseases that are not a big issue for non-pet owners may need to be considered (or may be higher on the list of possibilities) in pet owners. Knowing about pet contacts up front could help speed up diagnosis and proper treatment.

For example:

I have a flock of rare breed sheep. The other day, I had to assist with a lambing. Contact with newborn lambs and fetal fluids is the main source of the organism Coxiella burnetti, which causes Q-fever. If I became infected, the illness would start off with vague signs like fever and malaise. If I went to a physician at that point, I'd probably be told to go home, rest and take anti-inflammatories as needed (the old "take two aspirin and call me in the morning" type thing). If the physician knew I had sheep, he/she might ask about the risk of exposure for Q-fever. Upon hearing that I had a high risk exposure a few days earlier, Q-fever would be considered right away and appropriate measures could be taken.

Also, as strange as it sounds, in my utopian world physicians would ask about pet health. Yes, it may seem strange if your doctor were to ask "So how are you doing today? And how's your dog been feeling lately?" - but it might be important. Illness in your pet may be associated with illness in you or other members of your household. Knowing that a pet is sick might give some indication of that (a) certain disease(s) are more likely in a person. Also, if the sick pet has been to a veterinarian for testing, those results might be useful to the physician. There's no guarantee that a pet and owner that are sick have the same thing, but a general principle of medicine is that a single cause is more likely than co-incidental independent problems.

For example:

Similar to the case of psittacosis in a pet store employee that I reported about recently, let's say that you own a bird and it's been sick for a week or so. It's weak and not eating well. You then come down with a fever and cough - something that's not uncommon. However, when your astute physician asks about the health of your pets, he/she gets concerned about the fact that your bird is sick. Your doctor contacts your bird's veterinarian, and it becomes clear that the bird could be infected with Chlamydophila psittaci, the cause of psittacosis in people. Your doctor therefore puts psittacosis on top of the list of potential problems, and instead of telling you to go home and rest, he/she takes some blood samples to try to diagnose it the infection and may even start treatment right away. Because your physician identified a higher risk situation with your sick bird, you get prompt treatment, you start to feel better in 24 hours and it's unlikely you'll have any major problems. (The mortality rate from psittacosis is < 1% in people that are treated properly. If the diagnosis is missed, the mortality rate increases to 20%, and you also run the risk of complications such as heart valve damage.)

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An article by Toronto Star columnist Linda Diebel prompted me to write about a topic I've wanted to address for a while -  needlestick injuries. In the column, Ms. Diebel discusses her cat with idiopathic cystitis (a bladder disorder) and the need to treat it at home periodically with subcutaneous fluids (injections of fluid under the skin) and injectable medications. These are relatively easy procedures that most pet owners can manage with a little training, and it can be instrumental to improving the quality and length of life of some animals. However, safe and appropriate needle handling and needlestick injuries are rarely discussed.

Needle handling, needlestick injuries and avoiding contact with blood are (generally) very poorly managed by the veterinary profession. Needlestick injuries are incredibly common in the veterinary field, yet there is often little effort taken to reduce the risk of such injuries occuring. In contrast, there is a great deal of effort expended to prevent needlesticks in human medicine, largely because of concerns about transmission of viruses such as HIV and hepatitis B.  Fortunately, (currently) there are no common pathogens in pets that are transmitted by contact with blood and that are a significant concern in people. However, new diseases are emerging all the time, and there's no way to guarantee that the next big infectious disease in dogs or cats won't  be a bloodborne virus that can be transmitted to people by blood or dirty needles. It's not very likely, but you don't want to be the first person to get it if it does happen!

When it comes to injecting pets at home with fluids or drugs (e.g. insulin for diabetic animals) , some very basic precautions can greatly reduce the risk of injuries. The most important are:

• Know how to handle needles. You should be properly instructed on how to handle needles and treat your pet by your veterinarian.
• Make sure your pet is well restrained. If the animal is squirming around, you're more likely to inject yourself by accident.
• Never recap a needle. This is a very common cause of injury!  When trying to recap, it's easy to miss the cap and stick yourself.  Instead of recapping the needle, after use dispose of it immediately in an approved sharps container. These containers are puncture-proof and are designed to help prevent anyone from getting the needles back out (either by accident or intentionally).  You can get a sharps container from your veterinarian or a medical supply store. Once the container is 3/4 full, put the cap on it (once on the cap cannot be removed) and take it to your veterinarian for disposal. There may be a small fee for disposal, but it shouldn't be too expensive.
• Never leave an uncapped needle lying around anywhere for any period of time.
• Never put a needle in your pocket.  Pretty obvious why.
• Never put needles in your regular garbage.  People collecting and handling your garbage could get stuck by the needles.

Even though needlestick injuries associated with animals are incredibly common, fortunately they don't usually cause problems (although they still hurt, of course!). However, various types of infectious, allergic and other reactions can occur, and serious consequences, while rare, can develop. More information on needlestick injuries in veterinary medicine can be found in a commentary published recently in the Canadian Veterinary Journal.

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The latest edition of the Centers for Disease Control and Prevention (CDC)'s publication Morbidity and Mortality Weekly Reports consists of the revised Guidelines for Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents.

Among the highlights relevant to pets:

• HIV-infected patients should be advised to wash their hands after handling pets or other animals.
• They should avoid direct contact with diarrhea or any stool from pets, particularly stray pets or dogs and cats less then six months of age.
• Gloves should be worn when handling stool or cleaning areas that might have been contaminated with stool from pets.
• Contact with calves or lambs (e.g. on farms or at petting zoos) should be limited or avoided. Attention should be paid to hygiene and avoiding direct contact with animal manure when visiting such premises.
• Contact with reptiles, chicks and ducklings should be avoided because of the risk of Salmonella.

So, nothing earth-shattering or nothing we and others have not been saying all along. That's because basic measures, while not flashy, are the most useful tools. Use common sense, avoid contact with stool and high risk animals, and above all wash your hands.

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Methicillin-resistant Staphylococcus pseudintermedius (MRSP, sometimes misidentified as methicillin-resistant S. intermedius (MRSI)) is an increasing problem in dogs and cats. This highly drug-resistant bacterium is a particularly problem in skin and ear infections, and the number of infected animals appears to be increasing significantly. A related bug, methicillin-resistant S. aureus (MRSA) has been a major problem in people for decades, and MRSA is now being found with increasing frequency in animals as well. Sometimes people get confused when they are dealing with methicillin-resistant staph, and it's important to realize some of the differences between these two related bugs:

• MRSA is a huge problem in people and can be transmitted between animals and people. The role of animals in human disease is unclear, but there is concern that people can develop infections due to contact with infected or colonized animals.
• MRSP is rarely identified as a cause of infection in people. Transmission of MRSP between animals and people has been reported. However, this is much less concerning than with MRSA because people are much less likely to carry, transmit or develop infection from MRSP than MRSA.
• The recommendations that have been made for management of animals with MRSA largely involve improving general household infection control practices. These guidelines are only based on expert opinion (i.e. there are no studies (yet) to back them up), but they are reasonable and practical.
• Even less information is available regarding MRSP, mostly because it's not considered a major human health issue. That being said, you don't want to get a multidrug-resistant bacterial infection, even if it's uncommon. Therefore measures to reduce the risk of transmission of MRSP from pets to people is should still be considered.
• Strict isolation of infected pets is probably excessive. General infection control practices (e.g. handwashing after contact with the animal, avoiding contact with the infected site, limiting contact overall) are probably adequate, especially in households with no high-risk people (e.g. people with weakened immune systems, infants, elderly individuals).

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

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A search is on for a woman in Spring Hill, Florida who was attacked by a rabid cat while jogging.  The cat apparently jumped on the woman's back without provocation while she was out for a jog. The cat was later caught and found to be rabid, but not until after it had attacked three more people and a dog. Since the cat has been confirmed as rabid, and it is certainly possible that it may have bitten the jogger during the attack, there is a real risk to the unknown woman of developing rabies.

The potential for rabies exposure should be considered following any bite from a mammal. If the animal is acting strangely (attacking joggers would certainly qualify) and it's rabies vaccination status is unknown, the concern is much greater. It's important to identify any animal that has bitten someone so it can be evaluated to deterimine whether there is a risk of rabies. This would include examining the animal for clinical signs of rabies, and checking its vaccination status. Being vaccinated against rabies doesn't guarantee the animal doesn't have rabies, but it makes it very unlikely. Depending on the degree of risk and the status of the animal, observation of the animal in the home, strict quarantine, or euthanasia and testing might be indicated.

This jogger probably needs to be treated for rabies exposure, unless a bite can be completely ruled-out. This post-exposure prophylaxis (PEP) consists of an injection of anti-rabies antibodies, followed by 5 doses of rabies vaccine given over 28 days. It's not fun, but it's nothing like the old PEP method that people often hear about, which involved many more injections given in the abdomen. It's a small price to pay to avoid an almost invariably fatal disease.

More information about rabies can be found in our rabies archives and on the Worms&Germs Resources page.

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Deworming adult cats and dogs is a rather controversial area at the moment. Balancing concerns about animal health, zoonotic disease transmission, drug resistance, compliance and cost is difficult. Risks vary between different regions/climates and there are no clear answers. One area that is much less controversial is deworming of kittens and puppies (less than 6 months of age), as there is general consensus that aggressive deworming is needed in these animals.This is because young animals are much more likely to harbour parasites. They are also more likely to contaminate the household environment during the litter/house training process and tend to have very close contact with people. The greatest concern tends to be about roundworms, since they are very common in dogs and cats (especially young ones) and zoonotic infections  can occur (i.e. visceral and ocular larval migrans, similar to that caused by the raccoon roundworm, Baylisascaris procyonis).

Standard deworming guidelines are:

• Puppies should be dewormed at 2, 4, 6 and 8 weeks of age, then monthly until 6 months.
• Kittens should be dewormed at 3, 5, 7 and 9 weeks of age, then monthly until 6 months.

Further treatments depend on various factors, including the animal's lifestyle (risk of exposure), how common different parasites are in the region and perhaps whether there are high-risk people in the household. Your veterinarian can provide the best advice for your individual pet.

Another thing to remember is that not all parasites are killed by all dewormers. Specific deworming programs need to be set up to address different parasite risks.

More information about roundworms (and other parasites) in dogs and cats can be found on the website of the Companion Animal Parasite Council, an industry-funded organization.

Photo: A large mass of roundworms from the intestine of a heavily infected animal.

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Rabies clinics are common in some areas. They are typically one or two day events where people can get their pets vaccinated against rabies at very low cost. The good aspect of these clinics is that some animals that get vaccinated there would not otherwise be vaccinated. The downside of rabies clinics is that they are not the same thing as a normal vaccine appointment with a veterinarian. Rabies clinics are usually "assembly line" vaccination - the goal is to get as many animals vaccinated as quickly and efficiently as possible.  The animals are not given a physical examination and there is no discussion with owners about preventive medicine or other problems. Therefore, there is no opportunity to detect and address other health problems, which is (in my opinion) the most important aspect of routine vaccination appointments. There is also no opportunity for vaccination against other important diseases. 

Rabies vaccine clinics can be beneficial in situations where some people are unable (or, unfortunately, unwilling) to pay for a normal veterinary examination and complete vaccination. Anything that increases the number of animals vaccinated against this devastating disease is useful. However, rabies clinics also can compromise the health of animals (and potentially their owners) if they are the only routine veterinary contact. They can also end up hurting owners financially in situations where early disease would have been detected and addressed during a regular vaccine appointment. Often, diseases are much more difficult and expensive to treat when they are identified later.

So, while it's obviously tempting to take the cheapest option available, if you can afford a regular veterinary appointment, don't use rabies vaccine clinics. It will be better for your pet and for you to have a regular vaccination appointment with a good physical examination and full consultation.

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

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A recent column by pediatrician Dr. T. Berry Brazelton has caused quite a stir. Dr. Brazleton is apparently a very well known syndicated columnist, and he answered a question from a reader about her pregnant daughter and her cats. The reader was concerned about the cats lying on the baby. However, Dr. Brazleton focused on the risks of toxoplasmosis, which we've covered in previous posts and in a fact sheet in the Worms & Germs Resources page. He points out some valid facts and concerns regarding toxoplasmosis and prevention of this disease. However, he strayed off the logical, evidence-based trail with the statement "It would be better for the baby if your daughter would rid herself of the cats."

I am unaware of any medical, veterinary or public health group that advocates removal of pets from households with pregnant women. In fact, the Centers for Disease Control and Prevention (CDC) specifically state that pregnant women do NOT need to get rid of their cats. Dr. Brazleton also stated "Some cats will seek out the infants' mouths and noses and lie on them to smother them." While Dr. Brazleton may be well-versed in pediatrics, he apparently didn't take the time to look into current evidence and recommendations in this regard. His statements are ill-informed and irresponsible.

One should never dismiss peoples' concerns about disease or injury to babies from pets. The health of babies far superceeds concerns about pets. However, there are positive social and emotional aspects of pet ownership that similarly must not be ignored. There is simply no evidence that removing cats from households with pregnant women or infants is useful or necessary. The key is to consider basic (often common sense) infection control measures and proper animal management/training to reduce the risk of any adverse events.

Pet columnists have picked this article up and made various responses. One of the best I've seen is from Steve Dale. It provides some good basic information about why Dr. Brazleton's advice is unsound.

Comprehensive information about toxoplasmosis, and reducing the risks of disease, can be found on the Worms & Gerns Resources page.

Image credit: http://homepages.cwi.nl/~steven/julian/choclet/choclet.html

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One of my favourite stories about surgeons comes from a book by Irwin W. Sherman called "The Power of Plagues." In the pre-anesthesia and pre-antibiotic era, speed was considered the sign of a good surgeon. One surgeon, Robert Liston, was particularly renowned for his speed. However, speed sometimes lead to problems. In one surgery, he amputated a leg in 2.5 minutes, but the patient died of infection after surgery (a common event those days). During surgery, he accidentally amputated the finger of his assistant as well, who also subsequently died of infection. To top it off, he slashed the coattails of a surgeon who was watching, who "died of fright" thinking his organs had been slashed too. He's the only surgeon on record with a 300% mortality rate for a surgery.

These days, surgery is a lot more humane and safe. However, problems like surgical site infections still occur. They occur following a much smaller percentage of surgeries than they used to, but they can still be very serious.  Nowadays, more of these infections are being caused by multidrug resistant bacteria, which can affect and be transmitted between both animals and people. It's been stated that the time of maximal influence on surgical site infections beings and ends in the operating room (e.g. the most critical time for preventing infection is during the surgery itself).  However, there are things that can be done at home to help reduce the risk of infection.

• Antibiotics are usually NOT required after surgery, depending on what procedure was performed. But, if antibiotics are prescribed by your veterinarian, make sure you give the full course and follow all instructions carefully.
• Keep your pet from licking the surgery site. Trauma from licking and chewing, and bacteria from the mouth can help start an infection. If your pet is licking or chewing its surgery site, consult with your vet about ways to stop this.
• Keep an eye on the surgery site. If you see signs of infection such as excess heat, pain, redness, swelling or discharge from the site, talk to your vet as soon as possible.
• Don't touch the surgery site. You could contaminate the site with bacteria from your skin that could start an infection. Also, if an infection is present, bacteria could spread to you.  If you must touch the surgical site (e.g. if you need to change the bandage over it, or your veterinarian has instructed you to clean the site), you should wear disposable gloves.

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I did a presentation at a conference last week with a physician on the topic of "Pets and Immunocompromised Owners". It led to some interesting discussion.  People with suboptimal immune systems are becoming more common in households and they often own pets. These individuals are susceptible to infections caused by microorganisms that would not typically cause disease in healthy people, and they are also more susceptible to severe (including fatal) disease caused by microorganisms that would only otherwise cause mild disease. Therefore, there's a lot of concern about pets transmitting infection to immunocompromised people. Rarely is removal of pets from households of immunocompromised people necessary, but precautions should be taken to reduce the risks of disease transmission.

One topic that comes up periodically is testing for Bartonella henselae. This bacterium is the cause of cat scratch disease, which is spread by cats through scratches (obviously) but also through bites and by fleas. Cats that carry Bartonella henselae hardly ever have any signs of disease. In healthy people, cat scratch disease typically causes fever, local lymph node swelling, headache and fatigue.  Immunocompromised people, particularly people with HIV/AIDS, are at higher risk for severe disease, which can be fatal if it is not identified and treated promptly.  Similar disease can also be caused by other species of Bartonella that are not carried by cats.

Tests for Bartonella are not 100% accurate. Some tests just indicate exposure which does not tell you whether the cat is still carrying Bartonella or if it was previously exposed but already eliminated the bacterium from its body. False negative tests (e.g. the cat has been exposed but the test comes back negative anyway) can also occur. When considering screening tests, or any diagnostic tests in general, only do a test if there's a reasonable chance that the results will affect what you do.

• If a cat is positive, I wouldn't recommend removing it from the house. It may or may not be shedding Bartonella, so the key points for avoiding cat scratch disease are reducing the risk of bites and scratches, and controlling fleas.
• If a cat is negative, it's probably (but not guaranteed to be) free of Bartonella, but it could be infected later in life, and the key points for avoiding cat scratch disease are reducing the risk of bites and scratches, and controlling fleas.

So, if the recommendations are exactly the same in both cases, save your money and spare the cat the blood sample.  I don't recommend testing for Bartonella henselae.  The Infectious Disease Society of America also does not recommend testing (or treating) cats for Bartonella in their guidelines for HIV/AIDS patients.

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I've had this question a lot lately. Methicillin-resistant Staphylococcus pseudintermedius (MRSP), which is sometimes misidentified as methicillin-resistant S. intermedius (MRSI), is an important and increasing cause of infections in dogs and cats. After an animal has had an MRSP/MRSI infection, a question people often ask is how long they will carry the bacterium?

MRSP can be carried in the nose, intestinal tract or on the skin of a small percentage of normal animals. The implications of this are not clear, but it is reasonable to assume that carriers are more likely to develop infections in certain situations (e.g. if they sustain a wound or need to have surgery), and can transmit it to other animals (and possibly people, but that's much less of a concern with MRSP than with MRSA).

Back to the question... To be perfectly honest, we really don't know. However, I think it's reasonable to assume that some animals could carry MRSP for a long period of time - certainly weeks or months, maybe even years. Staphylococcu pseudintermedius is a common bacterium in healthy dogs and cats, and has basically evolved to survive on these animals. The methicillin-resistant versions are likely no different in this respect, so it's reasonable to assume that some animals could be long-term carriers. This makes controlling MRSP more difficult.  In contrast, MRSA appears to be only transiently carried by dogs and cats, probably because it is better adapted to living on humans than pets.

What you should do in the meantime if your pet has MRSP:

• Treat any infection as per your vet's instructions.
• Always complete the full treatment course.
• Wash your hands after contact with your pet, healthy or not.