Methicilin-resistant Staphylococcus schleiferi in pets

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. 

Stray cat roundup in New Jersey

In response to recent problems with attacks by stray cats and concerns about rabies exposure, Point Pleasant Beach, New Jersey, is planning to round up all the stray cats they can catch. Cats will be monitored in rented trailers for 60 days, and any cats that do not have signs of rabies will be adopted out (after being vaccinated and spayed/neutered). It's perhaps overly optimistic that all cats will be adoptable, since not all strays (especially older cats) are going to be appropriate for household pets, but they will hopefully find good homes for many of these cats.

While this program could be beneficial in some ways, let's hope a lot of thought has been put into it. This type of mass roundup and confinement is quite likely going to result in high transmission of many infectious diseases that circulate in the stray cat population. Hopefully there are plans for proper initial health assessment of captured cats, isolation of cats showing signs of infectious disease, cohorting of different groups to reduce the risk of disease transmission and use of good general infection control practices. Without these, they are asking for major problems.  Unfortunately, infection control is often not considered in situations like this until a major disease outbreak is already underway.

The 60 day quarantine period may raise questions, but it's a reasonable approach. If they were doing a formal rabies quarantine, it would be six months. The maximum incubation period for rabies in cats is not known, but it can be very long in humans in rare instances. Realistically, 60 days is a pretty good quarantine period under these circumstances. You can't be 100% certain that an animal isn't incubating rabies after 60 days, but it becomes very unlikely and I wouldn't be concerned after 60 days. Sixty days is also a good amount of time to identify (and hopefully address) any other major health issues.

Another issue that needs to be considered is ongoing population control efforts such as continued catching and adopting of strays, catching and neutering strays, and educational efforts to encourage people to have their cats spayed or neutered and discourage them from feeding strays. A lot of time and money can be put into a big one-time effort, but this town might end up in exactly the same stray cat situation in a year or two if nothing else is done.

MRSA and vancomycin in dogs

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.

Rabies bait safety

Rabies baiting is a common and effective way of controlling rabies in some wildlife populations, particularly skunks, raccoons and foxes. It involves dropping edible rabies vaccine, by airplane or by hand, into targeted areas. Millions of rabies baits are used across North America and baiting programs have been cited as a key aspect of wildlife rabies control. In one year, 1.3 million baits were dropped in targeted areas of Southern Ontario alone over a two-month period. A good series of pictures of rabies baiting is available here.

Rabies baits are usually a small rectangular block comprised of something that smells or tastes attractive to the targeted wildlife into which a liquid vaccine has been added. Some use fish meal and fish oil to attract wildlife. Others use combinations of fats, icing sugar, vegetable oil and artificial marshmallow flavour (don't ask me why - I'm certain there's a reason but I don't know if they've done taste-testing).

Often, the local public is notified in advance of the drops being made, and it is recommended that kids be closely supervised outdoors for a week or so to ensure they don't come into contact with the baits. It is also often recommended to keep pets indoors or on leash during the same period. (Pets are much more likely to be exposed to and to eat the vaccine than kids). It's also recommended that you wash your hands thoroughly if you have contact with a bait.

Rabies baits are quite safe, and these recommendations shouldn't cause concern. It's a case of being overly cautious. The baits are safe to touch, but it is still recommended that you don't touch them (if nothing else, they may make your hands smell pretty bad). Ingestion of a rabies bait by a person or pet is also unlikely to cause a problem. Any adverse affects are more likely to occur due to the non-vaccine component of the bait, particularly because of the typically high fat content. Ingestion of a lot of baits could certainly cause vomiting or diarrhea in a dog, just like ingestion of large amounts of other inappropriate foods.

Some groups recommend that you contact Poison Control if your pet has been exposed to a bait, but I'm not sure what they'd do in such a case. Other groups ask you to report to them that a pet ingested the bait, likely so they can consider exposure of people and pets when determining target areas for the next year. There's similar variation in recommendations if a person ingests the vaccine. Often it is recommended that public health be notified so they can record it, but it's very unlikely anything would be done.

On a related note, you cannot use rabies baits as a free way to vaccinate your pet. It might work, but there is no way to know, and if your pet is exposed, it would be considered unvaccinated if it was not properly vaccinated by a veterinarian with an appropriate dog/cat vaccine.

Image from:

"Horse strep" in people

I received the following question the other day: "I have a friend who had chemo embolization on tumor on liver in late June. She is in hospital now, and an abscess was discovered on liver.  Pathology results said "equine strep".  Her brother visited immediately after procedure, and he works with horse full time."

Streptococcus is a group of bacteria that includes many different species. There are two main species in horses Streptococcus equi subsp. equi (aka S. equi, the cause of strangles) and Streptococcus equi subsp. zooepidemicus (aka S. zooepidemicus, a cause of various types of infections). As you can guess by the 'equi' name, their natural host is the horse. Strep infections are very common in people, but rarely involve these two species. Nonetheless, infections with either Streptococcus equi or S. zooepidemicus can be found in people, but S. zooepidemicus is most common. Usually, these infections develop in people who are already sick for another reason, have compromised immune systems, or in young children. Interestingly, not everyone that is infected reports direct or even indirect contact with horses.

Back to the question: it's hard to say what's going on here based on the the general term "equine strep", but presumably the person has an infection with S. equi or S. zooepidemicus. Whether horses are actually involved will be tough (or impossible) to determine. It's a tempting hypothesis that the patient's brother carried the bacterium from the farm to the hospital, but I'd be wary about making a definitive statement about the bacterium's origin solely based on that. There are ways to investigate this further, such as trying to isolate Streptococcus species from horses on the farm, typing them and comparing them to the strain that caused disease in the person, but this type of testing is very costly and almost never performed, as human infection with these species is so uncommon.

This should be a good reminder that people who are sick and in hospital are at higher risk for developing infections, and they can get infections from bacteria that rarely cause disease in healthy individuals. While there is no proof of a link to horses (at least in this case), good infection control practices should be used whenever anyone visits someone in the hospital. That would include not wearing barn clothes to the hospital and paying close attention to handwashing.

This Worms & Germs blog entry was originally posted on equIDblog on 26-Aug-09.

HIV/AIDS, kids and pets

The Centers for Disease Control and Prevention (CDC) has released updated Guidelines for the Prevention and Treatment of Opportunistic Infections Among HIV-exposed and HIV-infected Children. A small but still important part of this document involves recommendations for contact with animals. It's a nice, balanced document that acknowledges the risk but doesn't make unnecessarily restrictive recommendations.

Among the important recommendations regarding animals:

  • When getting a new pet, avoid dogs and cats less than 6 months of age or strays: These animals are at higher risk for shedding various infectious diseases and are more likely to have problems with biting and scratching.
  • Avoid contact with animals that have diarrhea.
  • Wash hands after handling pets.
  • Avoid contact with pet feces.
  • Avoid contact with reptiles, chicks and ducklings: These are very high risk for Salmonella.
  • Avoid contact with calves or lambs at farms or petting zoos: These animals are high risk for various infectious diseases such as Cryptosporidium and Salmonella.

These recommendations also largely apply to other high-risk groups, including people (of all ages) with compromised immune systems and young children (especially less than 5 years of age). A key point is normal contact with common household pest using basic hygiene practices is considered a low risk. Infection control isn't rocket science. It involves basic and practical measures that can reduce risks associated with animal contact.

Expired antibiotics: Time's up

A recent post that discussed, among other things, expired antibiotics generated a lot of comments. Some accused me of various things and stated their belief that expired drugs are fine and that requiring antibiotics to be prescribed is a global conspiracy. I'll leave the conspiracy theory alone and just address the issue of expired drugs.

Expiry dates must be provided by manufacturers. They are essentially a guarantee that the stated level of active ingredient will be present at least until the expiry date. Drugs don't instantly vanish the day after, but once you have passed the expiry date, you no longer can be certain about what is present. It's possible the full amount is present, but it's also possible that less is present, and it's impossible to predict. If you don't know how much is present, you can't be certain that you are giving the proper dose. Giving inadequate doses is associated with treatment failure and increased likelihood of antibiotic resistance developing. Therefore, unless you have a pharmacology lab in your house (or readily accessible) to test expired drugs, you shouldn't use them.

It's not just my opinion.  Here's what some other groups say on the subject:

Centers for Disease Control and Prevention (CDC): "...make sure you properly dispose of leftover and expired antibiotics."

University of Michigan University Health Service: "Do not take expired antibiotics."

The Alliance for Prudent Use of Antibiotics quotes Dr. Alfred DeMaria, an Assistant Commissioner at the Massachusetts Department of Public Health (MDPH) suggests that "stockpiling of antibiotics is strongly discouraged because it could lead to inappropriate patient decisions to self medicate, incomplete courses of antibiotics that might select for resistant organisms, the eventual use of expired medications, and the depletion of national supplies for medically-indicated uses. Antibiotics should be selected according to the specific infection of concern."

The advice from these respected groups, who have no financial stake in the sale of drugs, sounds pretty clear to me. Trying to save a little money by re-using expired antibiotics is a bad idea. The infection might get better, but it might not. If it doesn't then the animal (or person) will be sick longer and may require more intensive (and expensive) treatment. If antibiotic resistance increases because of the use of inadequate doses, then more expensive drugs may be required and infections may be harder to treat. None of these are worth the potential cost savings.  This is a different situation than using expired drugs like painkillers for your headache. If those drugs are no longer effective, the worst thing that will probably happen is you won't get better, which you would know in short order and be able to address. With antibiotics it's harder to tell whether they are working early on during treatment (the critical time), and treatment failure could have much more serious consequences, both for the pet and for drug resistance.

When antibiotics expire, get rid of them.  Always complete prescriptions as directed and you won't have leftovers to worry about.

Raccoon deterrents

We've written various posts about raccoons, raccoon latrines and concerns about the raccoon roundworm (Baylisascaris procyonis). I received a question today about how to keep raccoons from coming back after a latrine has been identified and cleaned. It's a good question, and one without a simple answer.  I've looked through various sources and have found a wide range of recommendations. (Whenever I see such a wide-ranging list of recommendations, I wonder whether anything actually works.)

Home remedies include:

  • Sprinkling pure soap flakes on the lawn and watering thoroughly
  • Mixing bone meal in garden soil
  • Sprinkling diluted tabasco sauce over fruits and vegetables (wash before eating, as you should anyway!)
  • Lighting up the area where raccoons are a problem

Various commercial deterrent compounds are available, such as one that apparently has the scent of a coyote, or one that's a combination of vinegar, pepper and sulfur.

Another approach is motion-sensitive deterrents. Motion-sensor-based lights can be useful since raccoons often come rooting around in the evening or overnight, and lights that turn on when they approach could be effective. These would require a power source, which could be limiting in some places like sheds. Similarly, motion-sensor based systems that spray water or citronella (sometimes used to keep cats out of certain areas or off countertops) could be useful. Battery-operated units could be used anywhere. (Here's a link to one. I've never used it but it shows you what I'm talking about). There are also motion sensors that hook up to hoses.

One problem with deterring raccoons is their intelligence. They can often find ways around deterrents, or adapt to them. Along with any attempts to actively deter the raccoons, it is also important to try to reduce the desire of the raccoon to come to the location. If there is a good food source or other desirable attraction, the raccoon will probably try harder to stay around. Tightly covering garbage cans and removing other possible food sources (e.g. food for outdoor cats) are important steps. Making sure neighbours (or other family members) aren't feeding the raccoons is also important, because food is a great motivator.

Antibiotic loopholes and lunacy

People are justifiably concerned about overuse of antibiotics, in both veterinary and human medicine. There's ample talk about restrictions on use of antibiotics in animals (especially livestock), which is an area that needs good, objective research and discussion. Some politicians have made grand statements about restricting antibiotic use and have proposed strict legislation. (In North America, there's a lot more talk than action). However, I continue to be amazed that amongst all the hand-wringing about antibiotic use in animals, governments haven't taken the very simple initial step of making all antibiotics only available by a veterinarian's prescription. This seems to be a very logical first step, but it's one that almost never gets discussed.

A good example of why this type of regulation is needed comes from a website about Terriers, which says:

"Almost all human antibiotics can be used on dogs and almost everyone either has old antibiotics in their medicine cabinet or knows people that do. Look around, and you will probably find what you need."

  • What??!! Just what we need... recommendations that people sift through old drug supplies for a dose or two of who-knows-what, which may or may not be expired and may or may not be potentially useful for whatever problem is present, and may even be harmful. Determining whether or not an antibiotic should be used, and determining the drug and dose is not something that should be up to a pet owner. It should be up to a veterinarian.

"Drugs past the expiration date are going to be fine as long as they are no older than a year or so past the expiration date (even then they may be fine)."

  • Dumb. Drugs don't instantly go bad at their expiration date, but you don't know what you have left at that point. If you actually need an antibiotic, you need one that works like it's supposed to.

"If you prefer to order your medications outright, you can order cephelaxin (Fish-Flex) from most dog catalogues and it will cure 99% of your flesh wounds as well as most urinary tract and ear infections. Cephalexin or cefalexin is sold as a fish antibiotic in dog catalogues with full-knowledge it is being used for off-label treatment in dogs. It should cost about $30 for 100 250 mg. capsules, which is a perfect dose for a terrier."

  • Ugh!!  A good example of why loopholes like easy access to antibiotics for fish use need to be closed. Many dog internet sites sell fish drugs. I wonder what percentage of "fish" drugs actually make it into fish?

"You probably have some old amoxicillin around the house from the last time you got sick. This is fine to use even if "expired" more than a year ago. Expiration dates on non-liquid antibiotics are a marketing tool (i.e. they encourage people to throw good drugs down the drain) and have no scientific basis -- a fact demonstrated by the U.S. military."

  • Can't say I've seen that study. Expiry dates aren't a marketing ploy. You should use all the antibiotics prescribed, and if for some reason you have any left, you should throw the rest out. It has to do with health and proper use of antibiotics, not marketing.

Take home messages:

  • It's time for politicians to actually do something about antibiotic use and ban all over-the-counter access.
  • Beware of internet advice. Scrutinize sources of information carefully.

Veterinarian diagnosed with Hendra virus infection

A veterinarian, one of four people in Australia that were under close observation due to exposure to a horse with Hendra virus infection, has developed signs of infection.  Dr. Alister Rodgers is now in hospital in critical condition. He had close contact with a sick infected horse three weeks ago - Hendra virus was not considered initially, it was thought that the dying horse had been bitten by a venomous snake. Dr. Rogers didn't wear gloves or a mask when examining the horse because he had left them in his car.

Dr. Rodgers received experimental treatment for five days to try to prevent or reduce the severity of infection. He had returned home from hospital following the treatment only one day before he became ill. It has now been confirmed that he is infected. Only six people have been previously diagnosed with this rare disease; three have died. There were hopes that all of the exposed individuals would escape unscathed given initial tests showing no sign of infection and the experimental therapy, but it's clear now that early detection of infection is not easy.

Image: Coloured electron micrograph of Hendra virus (source:

This Worms & Germs blog entry was originally posted on equIDblog on 21-Aug-09.

Tea tree oil in dogs

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.

Raccoon latrines in Chicago

If you live in the suburbs of Chicago (or probably many other cities as well), chances are pretty good that you live close to a raccoon latrine. Raccoons like to defecate in specific areas (raccoon latrines) which can become highly contaminated with eggs of Baylisascaris procyonis, the raccoon roundworm. Human disease caused by this parasite is rare, but when it occurs, it can be devastating. Infected raccoons can shed around 20 000 Baylisacaris eggs per gram of feces (see image right), and the eggs can survive for long periods in the environment, so it's easy to see how biohazardous a raccoon latrine could be.

A study in the upcoming edition of Emerging Infectious Diseases (Page et al) looked at 119 backyards in the Chicago suburbs. Latrines were found in 51% of yards, with up to six latrines per yard! Baylisascaris eggs were found in samples collected from 23% of latrines. The likelihood of having a latrine in the yard was lower in houses farther away from forested areas. No other factors were identified as associated with the presence of a latrine, however there was a trend towards increased likelihood if a food source (e.g. bird feeder) was present.

The fact that raccoon latrines are so common and that a high percentage of raccoons shed Baylisascaris should raise concern, and emphasize the need for good hygiene. At the same time, the rarity of disease despite the widespread presence of infected raccoons should be remembered. You don't get infected by walking by a raccoon latrine, you get infected by ingesting (swallowing) the parasite. Avoiding this is simple, and as the folks at Barfblog (a food safety blog) would say, the key is: "Don't eat poop". Simple measures can reduce the risk, such as avoiding contact with raccoon feces and washing your hands after being in potentially contaminated areas. Young kids are at highest risk because they are more likely to put things in their mouths, so keeping children away from areas potentially contaminated by raccoon feces is important, along with good attention to hand hygiene.

Since raccoon latrines are an obvious source of infection and many (of the limited number of) human cases have been where latrines were close to childrens' play areas, eliminating latrines is also a good idea. Details on cleaning up latrines are available in an earlier Worms & Germs post.

Dropping rabies requirement for licensing: Greedy and dumb

Clallam County (Washington) is considering dropping the requirement that pets be vaccinated against rabies in order to get a license. It's pretty clear that this is only based on a desire to get more people to pay for licenses. Sheriff Bill Benedict is quoted as saying "My view on this is, we're leaving money on the table by not finding a way to get more people buying licenses."

This money-driven mindset makes no sense, and raises the question "what is the purpose of licensing pet?" Is it only to provide a source of government income (in other words, a tax on pet ownership), or is it for greater purposes such as helping protect the pet and human population?

Another quote from Benedict: "You would still be required to have your pet vaccinated, but that would be more of an issue between the pet owner and the veterinarian." This isn't an issue solely between the pet owner and the veterinarian. Rabies vaccination is still required by law. Veterinarians do not have a mandate or power to require vaccination and enforce the law. With this "You still need have your pet vaccinated (wink, wink, nod, nod)" approach, the municipal government is essentially saying, "We really just want you to pay us for a license. We don't really care whether your pet is vaccinated against rabies or not as long as you give us money."

A local veterinarian wrote to the commission that "Licensing pets is sometimes the only reason an owner will get rabies vaccines... Rabies vaccinance is the law of the state, the law of the county. Licensing, in my view, is less important than vaccinating for rabies and may facilitate even more rabies cases."

Well said. The county may get more money because more people will get licenses, but it's certainly possible that fewer pets will get vaccinated. Just one rabies exposure could negate the increased revenue from more licenses based on the high costs of rabies post-exposure treatment (let alone the risk of disease, stress of exposure, costs required for investigating cases...). Since all those costs would come from other peoples' budgets, however, I doubt they're too concerned.

Benedict also stated "Most pet owners -- in fact the vast majority -- if they're responsible enough to get a license, they're responsible enough to get a pet vaccinated."

Good thing he's not a lawyer. It seems to me that he just shot his argument down. If the majority of pet owners that are responsible enough to get a license are also responsible enough to get a pet vaccinated, then why is this change required?  An attempt to increase cashflow is not a good reason to change rules that are designed to protect the public and pets from a fatal disease.

Severe diarrhea outbreak in Florida dogs

Tuttle Animal Medical Center in Florida has reported six dogs with severe bloody diarrhea, vomiting and fever, over the past month. The affected dogs were from the same general area in Sarasota County, and all but one died within 24 hours. However, care must be taken when interpreting information such as this. Apparently, most dogs were owned by people with limited finances, so it's hard to say whether they would have died if aggressive (and expensive) treatment could have been provided. A disease like parvovirus is highly fatal without treatment, but survival rates are excellent if proper treatment is provided.

Initial testing of these dogs to identify the causative agent has been unsuccessful, including a rapid in-clinic test for parvovirus. Because of limited finances, complete diagnostic testing has not been performed, and it's likely that only a very limited range of possible causes have been investigated. That's a problem with a user-pay system such as this. There's no incentive for owners of dead pets to pay for further testing that could help understand the problem and/or help other peoples' pets.

Various experts have been consulted, but it sounds like there is minimal material (e.g. saved fecal samples) to use for further testing.  Trying to make a diagnosis based on clinical signs and basic laboratory data collected by the clinic during standard work-up and treatment is essentially impossible. Veterinary infectious disease expert Dr. Cynda Crawford told VIN News Service by e-mail last Wednesday "There is very little case material to work with, so am struggling with meaningful diagnostic approaches,...Everything is basically speculation at this point."

Florida's Division of Animal Industry is apparently "monitoring the situation." At this point, there's nothing that can really be done, but hopefully assistance with testing will be provided should further cases be identified. One official from this agency speculated that E. coli O157 could be the cause. That seems pretty unlikely. This bacterium can cause disease in dogs but it's quite rare. Six apparently unrelated cases due to such a rare cause seems pretty unlikely, although it shouldn't be dismissed.

A general tenet of medicine is "common things occur commonly." Situations like this are most often unusual presentations of a common disease (e.g. parvovirus) rather than a new disease. More aggressive diagnostic testing for known causes of disease, along with additional testing to try to identify new pathogens is needed if further cases are identified. Sometimes apparent outbreaks like this go away on their own without any intervention or diagnosis. Only time will tell whether this is a small local event or the "tip of the iceberg."

Rabid horse in Maryland

A horse in Harford county Maryland has been euthanized because of rabies. The horse first starting showing signs of disease in mid-July, which manifested as "striking changes in behaviour." The report doesn't say when the horse died, but animals typically die within a few days of the onset of neurological disease. The horse was transferred to the New Bolton Center where rabies was diagnosed. Subsequent testing showed it was a raccoon rabies strain, although that does not mean that a raccoon was the actual source of infection.

Public health officials implemented a 45 day quarantine of the farm. Stray cats (about 25) were caught and euthanized. Fortunately, the family pets were properly vaccinated and have received booster shots (plus presumably a period of observation at home... a much better situation than if they were not vaccinated).

People that had contact with the horse have received rabies post-exposure treatment. This includes one person who had to be tracked down overseas.

Harford County Health Department spokesperson Bill Wiseman said "There was never a risk to public safety. This incident was a great example of public health work in action and cooperation between local, state and in this case, international authorities." I don't buy the statement that there was no risk to public health. While the risk of rabies transmission from infected horses is very low, it's not zero. Rabid horses have killed people because of their abnormal and sometimes aggressive behaviour. Further, the fact that this horse had rabies means that it got it from something. Rabies can have a long incubation period so it's not guaranteed that it acquired it on the farm, but you have to be prudent and assume that there is infected wildlife in the area that could pose a risk for other animals or people. Public health authorities managed the situation well and reduced the public health risks, but there were certainly still risks.

Rabies vaccination is highly effective. There is no statement about whether this horse was adequately vaccinated but it's unlikely. Proper vaccination would likely have prevented this horse's death, as well as the death of the stray animals, cost of vaccination of people, cost of veterinary care for this horse, quarantine of the farm and the associated financial and emotional costs. A dose of vaccine that costs a few dollars could have saved thousands of dollars and emotional stress.

Rabies is a rare disease in horses but its severity means it should not be ingored. Vaccinate your horses.

This Worms & Germs blog entry was originally posted on equIDblog on 14-Aug-09.

Internet ying/yang: Artemisinin use and safety

Yesterday, I received a bulk email ad advertising a book about Chinese herbal medicine in pets.One of the introductory statements said that Chinese medicine is "becoming more popular as people realize the powerful yet gentle ways of TCM healing." On the same day, I received a Morbidity and Mortality Weekly Reports article entitled "Hepatitis temporally associated with an herbal supplement containing artemisinin."

Also known as qinghaosu, artemisinins are a class of compounds (drugs) that are used for the treatment of malaria. They are the active constituents of the herb Artemisia annua (sweet wormwood). Herbal supplements containing these compounds are marketed for "general health maintenance" (whatever that means), treatment of parasites and treatment of cancer.

In the MMWR case report, the CDC was notified about a person who developed hepatitis while taking an herbal supplement containing artemisinin. The person was prescribed the supplement by a naturopathic practitioner who attributed the patient's chronic abdominal pain to a parasitic infection. Six weeks of treatment was prescribed but 1 week into treatment, signs of hepatitis developed. No other causes of hepatitis were identified, and it resolved after the person stopped taking the supplement. That doesn't prove the supplement was the cause, but it is suspicious.

The supplement was tested and it had the amount of artemisinin that the label claimed. Artemisinin is generally considered a safe treatment for malaria, however the prescribed dose was much higher than the dose that is conventionally used for malaria treatment. It's unclear whether the liver damage occurred because of the dose, interactions with other compounds in the supplement, or an unusual reaction in this patient.

It's important to remember that herbal therapies are drugs. The fact that they are still in their natural state does not necessarily mean they are safer. In fact, there can be increased risks because of inconsistency in potency, dose and the presence of other compounds. With conventional drugs, extensive testing is done before they are released, to reduce the risk of them making people sick. With alternative therapies, the opposite occurs. There is no mandated pre-release testing so harmful products are only identified after they make a lot of people or animals sick.

A drug is a drug, whether it comes in a pill, liquid or leaf form.

Comparing dog and cat bites

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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Experimental treatment for Hendra virus-exposed horse personnel

Four people exposed to horses infected with Hendra virus in Australia are taking an experimental drug to try to prevent or reduce the severity of infection. All are currently healthy, but it is unknown whether the virus is incubating in them and whether disease may develop.  People can be infected with this virus through close contact with infected horses, as was the case with these four individuals. While human infections are rare, 50% of infected people die. Therefore, it's understandable that they would choose to try an experimental treatment.

These people will be treated for five days with intravenous ribavirin, an antiviral drug. There is evidence that ribavirin can kill Hendra virus in the laboratory, but it's not known if it actually does anything in infected people. It has some potential adverse effects, but given the severity of disease and high risk that these people have been exposed, it's certainly a reasonable decision. This treatment was also used in the Hendra virus outbreak in 2008. One person died, one survived after a long stay in ICU, and one did not get sick.  It's not known whether the drug did anything to help. The death of the treated person doesn't necessarily mean the treatment is not useful for some people or for certain stages of infection. Hopefully, ribavirin has a better chance of working when infection is only developing, before these people get sick.

This Worms & Germs blog entry was originally posted on equIDblog on 13-Aug-09.

Do not feed the bears

A 74-year-old Colorado woman that had been warned repeatedly not to feed bears was killed by one. The circumstances surrounding the attack are not known, but there was clear evidence of mauling. Wildlife officers had received numerous complaints for at least a decade that the woman was habitually feeding bears.  She was warned several times but never ticketed because of difficulty gathering solid evidence of the illegal activity. Wildlife officers and sheriff's deputies killed two bears after the attack. It was reported that a necropsy of the larger 394 lbs animal showed that it appeared to have been feeding on a human, but this has not been officially confirmed yet.

As we've discussed before, people often feed wildlife thinking they are helping the animals, but the opposite is true. Numerous problems are caused by feeding wildlife, including making animals dependent on people for survival, decreasing animals' fear of humans, encouraging animal encroachment into urban areas and generally increasing the chance for both human and animal injury and infection.

It's back: Hendra virus in Australia

Hendra virus, a virus that can kill horses and people, has resurfaced in Queensland, Australia. This bat-borne disease has caused periodic fatalities in horses and people that work with horses. The latest outbreak is thought to have killed up to three horses and resulted in the potential exposure of at least 30 people. The likelihood of these people getting sick depends on how close their contact was with the sick horses. Close contact with secretions from infected horses seems to be required to transmit disease. One person reported being snorted on by an infected, dying horse and being "covered" in blood, which is certainly concerning. An outbreak last year killed a veterinarian and hospitalized a veterinary nurse.

The farm in question is under quarantine and people that have been exposed are being monitored. There is no treatment for potentially exposed individuals, so they are in the unenviable position of having to wait and see if they get sick.

A virus like this is very hard to control. It's lives in fruit bats and only occasionally crosses into horses. The sporadic nature of disease makes it hard to control and predict when cases will occur. The key is early identification so that there is minimal exposure to other horses and people. People also need to take routine infection control precautions. One veterinarian handled an infected horse without using gloves or a face mask, as recommended, because he had left them in the car. Exposure to a potentially fatal infectious disease is not worth the few minutes of time saved by not following recommended precautions.

This Worms & Germs blog entry was originally posted on equIDblog on 10-Aug-09.

Attention Sears shoppers... Avoid rabid kittens!

State public health officials are trying to get the word out about a potential rabies exposure in Annapolis, Maryland.  A rabid kitten was discovered outside a Sears store at the Westfield Annapolis shopper center. The concern is that people may have handled the kitten and been exposed. It's a major concern with kittens because they can be hard to resist - a pathetic-looking/cute little kitten sitting around in a public place could easily be picked up by many people. Also, when rabies is found in a young kitten, there are often other rabid kittens from the same litter in the area. Rabid stray kittens have caused widespread exposure in the past, and this case may be no different.

Anyone who recently had contact with a stray kitten in the area in question should contact public health officials as soon as possible. Simply touching the kitten is not a rabies exposure risk, but anyone that has had any contact with a potentially rabid animal should talk to public health officials to determine whether there is any risk of infection and whether post-exposure treatment is required.

While kittens are hard to resist, avoid handling stray kittens. This is especially true if it's transient handling where you will never know what happened to the kitten afterwards (as opposed to someone adopting a kitten off the street - this is still risky from some standpoints, but at least you know if the kitten gets sick and you can make sure that it is tested for rabies or other other zoontic diseses, if need be).

Plague in a Colorado cat

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.

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G-force and zoonotic disease

It seems like whenever a hit TV show or movie features an animal, there's concern about the "101 Dalmatians effect," whereby there's a mad rush to get the animal for a pet. When 101 Dalmatians was a hit movie, there was a huge spike in sales of this rather unusual breed - a breed which is certainly not for everyone. This results in unqualified breeders and puppy mills churning out marginal or poor quality pets and people getting a pet that really doesn't suit them. The end result can be a lot of disappointment, heartache and abandoned pets. This pattern has been repeated with various other breeds and animal species, and there is concern that the same will happen with guinea pigs as a result of the new Disney movie G-Force.

In terms of human health, guinea pigs are relatively benign. Bites and scratches are probably the biggest concern, and are often the result of improper handling. Bites can become infected from bacteria in the guinea pig's mouth or from bacteria on the person's skin. Allergies are also a potential problem. The number of diseases that are known to be transmitted by them is relatively small, and the risk of disease transmission is rather low.

Lymphocytic choriomeningitis virus (LCMV) is a concern with all rodents. It typically only causes disease in people with compromised immune systems, but can result in fatal infection. The risk of a guinea pig carrying this virus is likely greatest in animals from large rodent breeding facilties and when there is contact with wild rodents.

Ringworm is perhaps the most common infection that people get from guinea pigs (apart from infections following bites). Even healthy guinea pigs can carry the fungus that causes this disease.

Guinea pigs can carry Salmonella, but they are quite susceptible to infection and usually get quite sick. The risk of a healthy guinea pig shedding Salmonella, especially for a prolonged period, is pretty low. The risk is presumably greatest shortly after purchase.

Rabies is always a potential problem in mammals but the risk is very low with small rodents such as guinea pigs. (Very low isn't zero though, since hamsters have been sources of potential rabies exposure).

There are other potential problems too, but they are all quite rare.

The keys to reducing the risk of infection are:

  • Purchase a guinea pig that looks healthy, is eating well, has no skin lesions or diarrhea, and is active and alert. Ideally, purchase an animal from a local breeder as opposed to a store that might have obtained the animal from a large breeder, via an animal warehouse, hundreds or thousands of miles away.
  • Learn how to properly handle a guinea pig to reduce the risk of bites and scratches, as well as injury to the animal.
  • Keep pet guinea pigs away from wild rodents.
  • Use good general hygiene. Wash your hands after handling the guinea pig and after contact with bedding.
  • Thoroughly wash any bites or scratches.
  • Take particular care in the period shortly after purchase.
  • Even though the cost of the guinea pig is less than the cost of a vet visit, a veterinary examination is important when the animal is sick. Apart from our ethical responsibility to take care of our pets, it's important to make sure that illness isn't caused by a disease that can be transmitted to people.

More information about the diseases mentioned above is available on the Worms & Germs Resources page. While we don't have a specific guinea pig info sheet yet, much of the information on the hamster information sheet also applies to guinea pigs.

Listeriosis in a dog from recalled meat?

A Windsor, Ontario woman is convinced that her dog acquired listeriosis afetr eating recalled hot dogs.  Last week, Maple Leaf Foods recalled various hot dog products because of low-level contamination with the bacterium Listeria monocytogenes, the cause of listeriosis. Her dog Tigger was fed four hot dogs one evening, and the next morning starting vomiting. He recovered after a few days of treatment. No specific testing was done to investigate the possibility of listeriosis.

Dogs can get listeriosis.  Non-specific signs of infection including vomiting, diarrhea and fever are most common. Neurological disease can occur in a small percentage of cases. Listeriosis is extremely rare in dogs, however, despite the fact that dogs are certainly exposed to the bacterium periodically. Just because the dog ate recalled meat and got sick, it does not mean that the dog had listeriosis.

No human illnesses have been reported in association with this recall, and it's very unlikely that this dog actually had listeriosis. It's possible but I really doubt it. Dogs get gastrointestinal disease like this all of the time, from a variety of causes. Eating four hot dogs in one night could itself cause diarrhea in some dogs.

Some tips come to mind from this story:

  • Limit feeding of treats to dogs. Four hot dogs is pretty excessive. Low fat, nutritious treats are better.
  • Pay attention to recalls. Don't eat recalled food or feed it to your pet. At the same time, don't overreact to recalls. We are exposed to potentially infectious agents on a daily basis, but a combination of our immune system, normal bacterial populations in the intestinal tract, low levels of contamination and other factors mean that we don't usually get sick. If you are concerned about listeriosis, make sure processed meats are cooked before feeding.
  • If you are really concerned or suspicious about a disease, make sure testing is done.
  • If you think food is the source of a problem, save a sample. It might be useful to test the food.

More information about listeriosis in animals is available in the Worms & Germs archives.

Humane society kids camp

I'm back from a week away with no internet access, so I have some catching up to do. One of the first things I stumbled across on my return was an article in the Guelph Tribune about a summer kids camp at the Guelph Humane Society. At the camp the kids get exposed to various aspects of animal care and welfare, and have field trips to sites like a Donkey Sanctuary and Butterfly Conservatory. Some parts of it sound quite good, but it's clear that the kids get to have a lot of contact with shelter animals, since playing with the animals is the "highlight of the camp," and as the camp director states "Who wouldn't want to hang out with cats and dogs all day?"

I have nothing against young kids having contact with pets (being the father of three young kids and the owner of multiple pets). Contact with animals is very rewarding for children, and a program to increase awareness about pets, animal care and the problems with overpopulation could be a great thing. However, I'm not sure that this is the best way. I only have a superficial idea of what happens at this camp based on the article, but I have a few different concerns.

Child safety

  • Any contact between people and pets carries some (albeit very low) risk of infection. Certain things increase the risk. One is young age. Kids are at increased risk of infection. The day camp had children between 5 and 13 years of age - the young end of this range certainly could be considered a high risk group.
  • Another issue is the increased likelihood that animals are shedding infectious agents. Shelter animals are definitely a high risk group, because of factors such as young age, stress, mixing of animals from various sources, illness, and under- (or lack of) vaccination and deworming.
  • The lack of good knowledge of temperament of these animals is another concern, as it's harder to predict whether an unfamiliar animal might be more likely to bite or scratch. I assume (hope) that the kids are only allowed to have contact with animals that have been assessed in some way, but it's difficult to know how an animal is going to react in certain situations.
  • Another consideration is the sometimes unpredictable nature of contact that kids have with animals. Young kids don't inherently know how to interact with strange animals. Even if they act very well around their own pets, they may act differently in a strange situation with animals that act differently, and not know how to detect or respond to signals that the animal is aggressive or afraid.  Education and supervision are important and should be a part of a program, but you can't instantly eliminate these risks.
  • The humane society environment can also be assumed to be pathogen-rich - there is a high likelihood that various surfaces (e.g. floors, counters) throughout the facility are contaminated with various bacteria, fungi and parasites.
  • Kids could also transfer infectious agents to the household, something that is of greatest concern if there are very young, elderly or immunocompromised individuals present.

Humane society safety

  • Humane societies are at constant risk of infectious diseases, including outbreaks. Outbreaks can cause major problems, including temporary closure, illness in staff or owners of newly adopted animals (e.g. ringworm), or mass euthanasia. Infection control measures can be highly variable in humane societies, and adding a group of kids to the mix certainly doesn't help. The more contact and movement in a facility, the greater the risk of disease transmission. Strict adherence to careful infection control protocols (which is not often the case, even at the best of times) is required. Good practices at the camp such as careful attention to hygiene, restricting contact with certain groups of animals, and very careful supervision could reduce the risk of disease transmission, but you can never eliminate the added risk that this type of program would bring.

Pet safety

  • Various infectious diseases could be transported home on the bodies of kids or their clothing. Some of these could pose a risk to any pets in the household. Risks are much greater if there are young, old, sick or inadequately vaccinated pets in the house.

I wonder whether the parents of these children were informed (in writing or otherwise) that their kids would be exposed to a increase risk of infectious diseases, bites and scratches, that they should take measures to reduce the risk of disease transmission when the child returns home, and what precautions are being taken at the camp.