Worms and Germs Blog

Cold weather + iguanas = botulism in dogs??

Scott Weese — Sun, 07 Feb 2010 17:17:37 -0500

The Associated Press is reporting a concern about botulism in dogs in Florida that might be linked to dead iguanas. The facts are pretty sparse at the moment and it sounds like both the diagnosis of botulism and the link with iguanas are hypothetical, but it's an interesting story.

Botulism is a very serious, hard to treat and rare disease in dogs. It's also very hard to definitively diagnose, which is one of the problems in a situation like this. It seems that a veterinary neurologist first raised concerns after seeing paralysed dogs (and no evidence of typical causes) and a common history of exposure to dead iguanas.

The recent and prolonged cold weather in south Florida has apparently resulted in widespread deaths of iguanas (who do not tolerate cold weather). The iguanas presumably didn't die of botulism, but if they had Clostridium botulinum, the bacterium that causes botulism, in their intestinal tract (something that can be common in some animal species), dogs could ingest the bacterium or (more likely) botulism toxins that were produced by the bacteria in the iguana carcasses after death. Botulinum toxin is extremely potent and ingestion of minuscule amounts is enough to cause serious (including fatal) disease.

Testing is pending on some of the affected dogs. It would be nice if someone would test some dead iguanas as well, to see if there is really a link. This type of outbreak, however, often passes without a definitive diagnosis because of the difficulties diagnosing the disease. Regardless, keeping your pets away from dead iguanas (and other dead critters) is a good general rule.

Watch out for rabbit pee

Scott Weese — Fri, 05 Feb 2010 08:33:00 -0500

Urine from healthy animals is typically considered to be of little to no risk to people. This is generally true, at least for the otherwise healthy human population, but like with most things in infectious diseases, there are exceptions. An interesting one in rabbits is a bug called Encephalitozoon cuniculi. This microorganism (now classified as a fungus, but previously considered a protozoal parasite) is very common in healthy pet rabbits. In fact, the majority of rabbits have antibodies against E. cuniculi and may have it living in their bodies, particularly in the kidneys. It can cause infection of the brain, and is an important cause of neurological disease in rabbits, but more often than not it lives within the rabbit without causing any problems. Rabbits can shed spores of this organism is their urine, although they mainly do this only in the first few weeks after they've become infected, and shedding after that may be intermittent.

E. cuniculi is one of a group of microorganisms that became much more important when the HIV/AIDS epidemic hit. While rarely a cause of disease in people in the pre-HIV era, E. cuniculi is recognized as a potential cause of infection in people with compromised immune systems, particularly people with AIDS. Infections of people with normal immune systems are extremely rare.

It's always a challenge deciding what to do with a microorganism that can be shed by a large number of healthy animals. One reference "strongly advises" routine testing of rabbits, but that makes no sense to me. Here's why:

Screening always comes down to a question of what you would do with the results. If you get a positive antibody test, it means that the rabbit has been exposed sometime in its life, but that does not mean that it is necessarily still infected or shedding spores - so it's not really convincing.
Tests can be done to detect spore shedding but they are not particularly reliable. Since infected animals shed spores intermittently, a negative result here isn't convincing either.
If the animal is positive, what would you do? If the household has no immunocompromised people, I'd say do what you've always done, and pay attention to good hygiene.
If the animal was "negative," I'd say do what you've always done, and pay attention to good hygiene... same as for a positive rabbit.
If there is an immunocompromised person in the house, I wouldn't say to get rid of the pet, since there's no evidence that's necessary. There is also no evidence that treatment is useful to eliminate E. cuniculi shedding rabbits. If the animal is positive, immunocompromised persons should avoid contact with urine and feces, and use good personal hygiene... just as they should do if the rabbit is negative!

More information about E. cuniculi in rabbits can be found in our archives.

Kissing a frog might get you more than a prince

Scott Weese — Wed, 03 Feb 2010 13:25:00 -0500

The Hollywood effect is quite real when it comes to various trends, including pets (remember the glut of Dalmatians after 101 Dalmatians?). I can understand how seeing a cute puppy of some breed might lead to people wanting to get one. However, when Disney's The Princess and the Frog was released, I didn't really think a lot of people who watched this movie were going to start running around kissing frogs. I assumed that some degree of common sense would apply. Apparently, I was wrong.

Various news outlets are reporting that at least 50 children (mainly kids under the age of 10) have become sick in the US after copying the movie's Princess Tiana by kissing frogs. There's not a lot of information regarding what they contracted, whether the illnesses were all clearly linked to frogs, or whether these were truly associated with the movie, but there are certainly disease risks associated with kissing a frog. While we pay more attention to reptiles as a source of Salmonella, the risk is also present with frogs, and the best thing is to do is assume that all frogs are carrying this potentially harmful bacterium. Accordingly, high-risk people (e.g. kids less than 5 years of age, the elderly, people with compromised immune systems) should have no contact with frogs - they shouldn't even be in the same house. Hands should always be washed after touching a frog, and no one should ever kiss a frog. The chances of living happily ever after with a prince are much lower than the chances of a nasty bout of diarrhea (or worse)!

Autism/vaccine link study now fully retracted

Scott Weese — Tue, 02 Feb 2010 11:37:00 -0500

The medical journal Lancet has fully retracted the flawed 1998 study that raised a link between MMR (measles, mumps, rubella) vaccination and autism in children. This study fueled incredible debate and was a driving force in the anti-vaccination movement, and subsequent declines in vaccination rates were a key reason for the resurgence of measles. It also fostered general anti-vaccination sentiment that has continued to affect decisions regarding vaccination of people and animals.

The study has come under fire for years and has been highly controversial, with strong opinions on both sides. In 2004, the journal issued a partial retraction based on a conflict of interest of Dr. Wakefield's (the lead researcher), since it was revealed that he was being paid by lawyers acting for parents who believed their children had been harmed by MMR vaccination. The new full retraction goes much beyond this, and is based on problems that have been revealed with the scientific method, reporting of what was done, plus ethical issues pertaining to ethical committee approval.

The UK's General Medical Council ruled last week that Dr. Wakefield had shown "callous disregard" for the children involved in the study and acted "dishonestly." He faces being stripped of the right to practice medicine in the UK. Accordingly, all of the findings of this study are considered invalid.

Image source: http://www.dailymail.co.uk

Reptiles and infants don't mix

Scott Weese — Mon, 01 Feb 2010 13:40:00 -0500

A recent report in the Journal of Pediatrics (Tabarani et al 2010) describes a case of infection around the brain, at the site of a previous subdural hematoma, in a five-month-old child. Four reptiles (all bearded dragons) were present in the child's foster household, but the foster parent reported that the baby did not have any contact with them. Salmonella Houtenae was identified as the cause of the infection. The reptiles were an obvious potential source given what we know about Salmonella and reptiles, the unusual Salmonella strain that was isolated from the baby, and the lack of any other obvious risk factor. All previous human infections caused by this type of Salmonella have been associated with reptiles, and all occurred in young children. Unfortunately, the reptiles in this case were euthanized before they could be tested.

This report highlights a few important points.

Direct contact with reptiles is not needed to cause an infection. There are many reports of people (especially infants) being infected by Salmonella from a pet reptile despite them having no direct contact with the animal. The common statement that 'there's no risk to my child because my child is never allowed to touch the animal' is completely false.
Reptiles should not be in households with children less than five years of age. In this report, the child was in a foster home. In some jurisdictions, reptiles are banned from foster homes for this very reason.
The majority of reptiles carry Salmonella. This is expected and impossible to prevent. That's why people at high risk of serious infection (e.g. young children) should not be around them. It's also why euthanasia of the reptiles in this case was highly questionable. Why kill the lizards for carrying a bug that we assume they (and most other reptiles) normally carry? Finding them a new home that doesn't have high risk people would be more appropriate.

Image: Central Bearded Dragon (Pogona vitticeps) (photo credit: Eigene Arbeit, 2007)

Antagonzing piranha... Maybe not a good idea

Scott Weese — Thu, 28 Jan 2010 14:39:00 -0500

Pet bites are a big problem. Dogs bites in particular are far too common and can result in serious injury or even death in a small percentage of cases. Bites from other pet species also happen, but the extent of the problem is not clear. A good general rule is if it has a mouth, it can bite.

Another good general rule is if it has numerous sharp teeth, is a carnivore and your as upsetting it, you should get your hand out of the way. Pet store owner Dave Brown found this out the hard way, although in this situation he has the dubious distinction of having been bitten by a fish.

It seems that Mr. Brown was trying to catch a piranha that he was selling. I would have thought the standard way of catching a fish, not to mention a six-inch-long carnivorous fish, would be to use a net. Apparently not. Mr. Brown used his bare hands, and after a couple unsuccessful attempts to catch the fish, the piranha fought back, sinking his teeth into the store owner's thumb. The bite was severe enough that stitches were needed. According to Mr. Brown "There was blood everywhere. Every time I had him in a plastic bag the fish would bite through it. He was quite a feisty one." Personally, I think if a carnivorous fish was repeatedly trying to attack me through the bag, I'd probably change my approach to catching it.

According to a local fish expert, "[Mr. Brown] was very unlucky as these fish normally just attack when they're hungry. It may have been a bit peckish."

Fortunately, apart from a sore thumb, it sounds like the biggest problem Mr. Brown will face is the harassment that I assume he's going to take from friends after being bitten by a fish.

Images from: http://www.dailymail.co.uk/

2008 Australian Hendra virus recap

Scott Weese — Wed, 27 Jan 2010 16:47:00 -0500

The latest edition of the journal Emerging Infectious Diseases contains a paper describing the 2008 Australian Hendra virus outbreak in horses and people.

In this outbreak, there were five horses infected and two humans infected. The horses predominantly had signs of neurological disease, not respiratory disease like some other reports describing this disease. Four horses died. One recovered but was euthanized for public health reasons.

Two people became infected after working with the sick horses, which represents 10% of the total veterinary staff that were exposed to the infected horses. Both people started off with influenza-like illness, which seemed to improve initially, but then signs of severe neurological disease developed. They were treated with ribavirin, an antiviral drug, as part of an experimental treatment. One of them died after 40 days of illness, the other person survived.

The authors stressed that the effectiveness of ribavirin could not be determined, but they recommend it nonetheless because of the severity of Hendra virus infection and lack of other options. Ribavirin was also used in the 2009 outbreak, but it is clearly not 100% effective since one person died there also.

A number of concerning activities occurred that put people at risk of infection, including a "percutaneous blood exposure while euthanizing an infected horses" (they didn't explain exactly what this was, but it could have been a needlestick), low use of personal protective equipment, and contact with potentially infectious body fluids. This is unfortunately not surprising since the approach to infection control (particularly in terms of zoonotic infections) is often lax in equine medicine. That certainly has to change, particularly in areas where Hendra virus may be present.

Much more information about how to control this potentially devastating virus is needed. Fortunately, infections are uncommon and it is restricted to a fairly small geographic range in Queensland, Australia.

Image source: http://animalphotos.info/

This Worms & Germs blog entry was originally posted on equIDblog on 27-Jan-10.

More rabid raccoons in Central Park

Scott Weese — Tue, 26 Jan 2010 08:23:00 -0500

Eight more rabid raccoons have been found in New York's Central Park over the past two weeks. These, plus the 12 rabid raccoons reported in the park last year, represent a major increase in disease frequency since only 1 rabid raccoon was identified in Central Park from 2003-2008. That's a concerning development given the number of people that visit this 843 acre park in the heart of New York city every day.

In response, the city's Health Department has started an education campaign to alert people to the risk, and tell people to stay away from wildlife, report any sick animals and to keep their dogs on leashes. Every pet owner also needs to make sure their dog's rabies vaccine status is up-to-date, even if they always keep their dog on a leash, because you never know what a rabid raccoon will do (such as attacking a leashed dog that walks by). There are also plans to vaccinate raccoons in and around the Park, however I couldn't find details about what type of vaccination program will be used.

Musings about antibiotic therapy in dogs and cats

Scott Weese — Mon, 25 Jan 2010 20:26:00 -0500

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.

Staphylococcus (pseud)intermedius meningitis in a child

Scott Weese — Sun, 24 Jan 2010 07:23:00 -0500

A paper in the International Journal of Infectious Diseases (Durdik et al 2010) describes a case of meningitis in an 11-month-old child caused by S. intermedius. (Presumably, the bacterium was actually S. pseudintermedius and they’re behind the times on identification of / nomenclature of this bacterium). This is the first report of this bacterium as a cause of meningitis in people, and obviously it’s a concern because of the potential severity of meningitis. Fortunately, the child made a full recovery with proper treatment.

S. pseudintermedius is a normal inhabitant of the skin and other body sites in dogs, and is found less commonly in cats. In this case, the child’s family owned a dog, but the dog lived outside and no direct contact was reported between the child and the dog. Indirect contact, such as someone bringing the bacterium in on their hands after touching the dog, would certainly be a possible route of transmission. Unfortunately, the authors of this study did not investigate the dog as the potential source and there was no attempt to isolate the same bacterium from the dog. The dog is certainly a likely source of infection here since S. pseudintermedius is not commonly found in people, and when it is, it is often associated with dog-contact.

There seems to have been an increase in reports of Staphylococcus intermedius/pseudintermedius infections in people lately. Reports are still very rare but there have been a couple in the past six months. That could be because there are more infections, but it could also be that people are just writing up the cases or that labs are getting better at identifying the organism. Overall, the number of apparent human infections caused by this dog-associated bacterium is very low. While it is clearly a bacterium that can infect people, the risks to people in contact with pets is also very low. “Low” doesn’t mean “no”, however, and the very low but not negligible risk of S. pseudintermedius infection is just one of many reasons to pay close attention to good hygiene practices around pets, and ensure that your physician knows if you have pets.

Fewer sinks in veterinary clinics??

Scott Weese — Fri, 22 Jan 2010 18:31:00 -0500

Click here for a link to a presentation by an architect about veterinary clinic design. This video clearly shows why people that are designing clinics need to be thinking about infection control (and that some are clearly not doing so). This person talks about the trend towards not placing sinks in exam rooms. This is news to me, and a major concern, because one of my major points when consulting on clinic design is making sure there are sinks in all exam and treatment areas. The farther you have to walk to find a sink, the less chance you’ll wash your hands and the greater chance you’ll contaminate things on the way to the sink.

One of this person's arguments for not putting sinks in exam rooms is truly ludicrous. Basically, he says that pet owners are more and more in tune to hand hygiene, and if they see a sink and someone not use it, they get concerned that the vets hands are dirty. His reasoning is that not having a sink will prevent people from thinking about hand hygiene issues. For one thing, I think he’s underestimating the intelligence of pet owners - they don’t need to see a sink to think about hand hygiene. People are becoming much more aware of the need for healthcare providers to wash their hands, and this is filtering down to their perceptions of veterinarians as well. Instead of taking sinks out of exam rooms, if a vet is concerned their clients have a negative perception of their hand hygiene practices, there's a simpler solution: actually practice good hand hygiene (and do so where owners can see it so they can be confident it's being done!). The architect is correct that hand sanitizers are now more widely used, but he is incredibly wrong with his assumption that hand sanitizers replace hand washing. They don’t. Hand sanitizers are great but handwashing is still required in many situations.

Hopefully this architects assessment that sinks are disappearing is wrong. Vets and architects need to think about infection control when designing clinics. It’s easy to incorporate good infection control when building a clinic but very hard to retrofit a poorly designed clinic.

Bare feet and horse bugs

Scott Weese — Wed, 20 Jan 2010 10:00:00 -0500

I assume that people wouldn't voluntarily and regularly walk around barefoot on dog feces (or feces of any type), yet it's perplexing that some people regularly clean out horse stalls in bare feet (I've seen it done!). While horse manure may not be as inherently gross as dog poop, it's still feces, and like all feces contains a huge population of various bacteria, some of which can be harmful. The risks of barefoot mucking may also extend to bare feet inside boots, although I don't think sock-averse people need to panic.

An article in the International Journal of Infectious Diseases (Friederichs et al) describes infectious arthritis of the shoulder of a horse owner that was caused by Streptococcus zooepidemicus, a bacterium commonly found in horses but rarely associated with disease in people. The person didn't have a wound in the shoulder area or any other obvious route for the bacterium to get to the shoulder joint. They searched for a source of the infection and all they found was a chronic lesion on the person's foot. This, combined with the patient's history of taking care of his horses in "bare feet in boots", led them to implicate the foot as the source of infection.

The idea, I guess, is that socks would be a barrier to help prevent contamination of the foot wound. That makes sense to a degree - the person could contaminate his foot with S. zooepidemicus from his hands (probably acquired from touching the horse's nose) while removing the boots, or manure could work its way into boots and directly contaminate the wound. Both are possible, but we have to be a little cautious in interpreting these conclusions. However, this is a bacterium that is associated with horses and the foot lesion is certainly a possible route of entry.

Overall, this should be considered an interesting report of a very rare problem, not something that indicates a major concern. However, there are a few good points to take away from this story:

If you have a wound or chronic lesion of any sort, make sure you take measures to reduce the risk of bacterial contamination when working around horses. This might be as simple as making sure it's covered by clothing, or something more involved like using an impermeable bandage.
Hands are probably the major source of infection transmission, and good hand hygiene is important after horse or stall contact, particularly if you have an underlying disease.

More on pets and the risk of MRSA

Scott Weese — Wed, 20 Jan 2010 08:27:00 -0500

We've seen reasonably good evidence of the potential involvement of pets in the transmission of methicillin-resistant Staphylococcus aureus (MRSA) for a few years, and a study recently published in the Journal of Hospital Infection (Loeffler et al 2010) sheds a little more light on the subject.

In this UK study, they tested 608 veterinary staff and pet owners in contact with pets that were carrying MRSA or methicillin-susceptible S. aureus (MSSA). MRSA carriage was identified in 12.3% of veterinarians that treated MRSA-infected animals and in 7.5% of their owners (although the chicken vs egg conundrum comes up, i.e. are vets that treated MRSA -infected pets more likely to have MRSA because they got it from the pet or because they already had MRSA and infected their patient?). These numbers are relatively consistent with a small number of other studies that have looked at these groups, and are higher than the expected carriage rates in the general population. This is highlighted by the results from people that had contact with animals only carrying methicillin-susceptible S. aureus, since MRSA was only identified in 4.8% of veterinary staff and 0% of owners in this group. Veterinary personnel were significantly more likely to carry MRSA than pet owners. As expected, virtually all MRSA from people and pets in the study were the predominant strains present in human hospitals in the UK.

We shouldn't fear MRSA or our pets, but we should respect the potential for infection and act accordingly. Mainly, this involves basic practices like:

Good hygiene: washing hands regularly after handling pets
Avoiding contact with infected body sites in pets, and preventing pets from having contact with infected body sites in people
Prudent antibiotic use in both veterinary and human medicine
Proper and timely diagnostic testing to identify MRSA infections, to permit proper treatment and earlier implementation of appropriate infection control practices.

Ultimately, MRSA in pets is a human-borne disease. Most pets that have MRSA presumably acquire it from a close human contact, so efforts at controlling MRSA in pets need to be directed at both the pet and human aspects. Uncontrolled MRSA in people will lead to increased risk for pets, and for pets to be a source of subsequent human infection.

Image: Seven-month-old British Shorthair (photo credit: Tamila Aspen)

Rabid calf at educational centre

Scott Weese — Tue, 19 Jan 2010 12:02:00 -0500

Rabies has been diagnosed in a 6-week-old Jersey calf at a Maryland educational centre, raising concerns about exposure of farm visitors, particularly groups of school children. At least 70 kids and an unstated number other visitors had recently visited the farm.

Fortunately, the farm in question is not open to the public, so they should have an easier time identifying people who have been there (e.g. school groups). Contact tracing is underway to try to identify people that had contact with the calf. Simply petting the calf or being in the general area does not pose a risk. The main risk would be from contact of open wounds with the calf's saliva, or a bite. We don't typically associate bites and calves, but it can happen when calves are allowed to suck on someone's fingers - if the person sticks their hand in too far he/she may get chomped by the calf's sharp molars. Public health personnel are trying to identify people who had contact with the calf, then they'll determine whether there was a chance of exposure to the virus. People that were potentially exposed to rabies will undergo post-exposure prophylaxis, consisting of a shot of anti-rabies antibodies and four doses of vaccine over the course of a month. Not fun, but much better than getting this almost invariably fatal disease. At least nine students have started treatment so far.

Petting zoos and similar events are a concern in terms of disease transmission because of the large number of people that can be exposed to animals and the high percentage of children that are involved. Rabies is uncommon in petting zoo animals, but it is periodically identified at such a facility/event, often resulting in the need for post-exposure treatment of large numbers of people. Vaccination of petting zoo animals against rabies should be a standard practice. This calf, being only six weeks old, was too young to vaccinate, but if the calf's mother was vaccinated the risk of rabies would be lower (because the calf would get antibodies from the mother). There's no information about the cow's vaccination status or much else about the calf, apart from it being a recent acquisition.

The fact that a recently acquired young calf was allowed to have contact with the public is questionable management, because young calves are a high risk group for certain infectious agents like Cryptosporidium and Salmonella. The CDC recommends that children less than five years of age not have contact with young calves. Since young kids are frequent visitors of places like this, having calves (or at least letting people have direct contact with them) is quite questionable as well. Hopefully there will be a good review of vaccination, animal acquisition and animal contact protocols for this facility to reduce the risk of future exposures to rabies or other infectious diseases.

Baylisascaris in Winnipeg

Maureen Anderson — Wed, 13 Jan 2010 16:22:00 -0500

There was another paper published in the August issue of the Canadian Veterinary Journal about Baylisascaris procyonis (roundworms) in raccoons, this time in Winnipeg, Manitoba (Sexsmith et al 2009). The study was actually undertaken after infection with B. procyonis larvae was identifed as the cause of death of several animals in the collection at the Assiniboine Park Zoo in Winnipeg.

The researchers collected feces from 52 active raccoon latrines around the city and from 114 "nuisance" raccoons that were caught, euthanised and submitted for necropsy to the local lab. Interestingly, the vast majority of latrines and nuissance raccoons were found close to the two major rivers that run through Winnipeg. Half (50%) of all the latrines were positive for roundworm eggs on at least one sample (out of a possible 3). Among the necropsied raccoons, 61/114 (53.5%) were positive for roundworms. Adult raccoons were almost four times as likely to carry roundworms than juveniles (which is in contrast to a previous study that found juveniles more likely to be infected), and bigger raccoons (over 2.75 kg) were more than seven times as likely to carry roundworms compared to smaller animals. Although there are regions where the prevalence of B. procyonis s reported to be very low, Winnipeg, like many other regions of North America, has joined the ranks of those where the prevalence is high and the public needs to be aware of the associated risks.

The most severe zoonotic disease caused by B. procyonis is called neural larval migrans (NLM), which results from migration of parasite larvae through the central nervous system (i.e. brain). Two of the reasons this is much more of a concern with raccoon roundworms (Baylisascaris) compared to dog and cat roundworms (Toxocara) are:

1) A massive number of parasite eggs are passed in the feces of infected raccoons (which typically have a very high burden of adult worms). Coupled with the fact that the eggs are further concentrated in areas where many raccoons defecate (latrines), this can lead to heavy exposure of people (or animals) who come in contact with the soil in these areas, which greatly increases the risk of infection.

2) The larvae of B. procyonis are very active migrators, and they get bigger as they migrate through tissues - much bigger than Toxocara larvae ever get, which means they also tend to cause a lot more damage before they're finally (if ever) trapped or killed by the body's immune response.

Natural infection of dogs living in the same areas as raccoons has been found - it's not common, but it appears to occur frequently enough to warrant noting. Dogs and cats can also be infected by their own species of roundworms, which will also result in parasite eggs being shed in the feces. It's important to have your veterinarian perform a fecal examination for your pet on a regular basis so any parasite infestations (roundworm or other) can be treated.

Dogs and cats may also be susceptible to larval migrans in the same manner as people (and the animals at the zoo in Winnipeg) if they are exposed to high numbers of infectious eggs. Remember that roundworm eggs must be swallowed in order for infection of any kind to occur, so good hand hygiene and avoiding soil contamination of food are key to preventing transmission. Also, do not allow your pet to dig or play in an area where raccoons defecate (preventing direct contact between your dog and raccoons should go without saying!). And of course, feces of any kind (and from any species) should be treated as infectious material, and handled with appropriate precautions.

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

Seagulls, beaches and bad bugs

Scott Weese — Fri, 08 Jan 2010 16:05:00 -0500

Just as I'm getting ready to go on vacation (that will hopefully involve some time on the beach), I read an article in the latest edition of Emerging Infectious Diseases about seagulls and beaches as reservoirs of multidrug-resistant E. coli (Simoes et al 2010). In this study, the researchers collected seagull poop from beaches in Porto, Portugal and tested them for the presence of extended spectrum beta-lactamase (ESBL) E. coli, a highly drug resistant form of this common bacterium. Thirty-two percent (32%) of the E. coli they isolated were ESBL, a pretty impressive rate in wild birds that would not be directly exposed to antibiotics. Various E. coli strains were present, including some that can cause severe disease.

In some respects this is pretty concerning, and in other respects not too surprising. We know that birds in various (including remote) regions can carry multidrug-resistant bacteria. The ability of wild birds to carry these bacteria, combined with the wide geographic range that some bird species have, raises concern about the role of birds in the spread of antibiotic-resistant bacteria, as well as the potential for contracting a nasty drug-resistant infection while on the beach. Birds certainly have the ability to help spread certain types of bacteria over wide ranges. However, their overall role is probably very limited compared to the role played by people and (domestic) animals. For birds to become carriers of these bacteria, they have to pick them up from somewhere, which presumably doesn't occur until the bacteria have built up to a good level in people and/or animals. I doubt that birds account for many human infections. Antibiotic exposure through antibiotic residues in water or food sources could also play a role in the presence of these bacteria in birds, but that's an area that's not well understood.

So, how does this influence my time on the beach? Not much. I wasn't really planning on having contact with seagull poop, and this paper just reinforces that basic precaution. Other basic measures such as keeping open sores covered, avoiding cuts by wearing shoes in rough areas or sand that might be contaminated with sharp objects, avoiding contamination of food with sand, avoiding areas with obvious bird poop contamination, and hand washing before eating and after leaving the beach are easy to do.

Handling rabies exposure in horses

Scott Weese — Tue, 05 Jan 2010 18:34:00 -0500

I received newsletter today from Intervet (a pharmaceutical company) that is targeted at equine veterinarians. One article discussed rabies in horses. It wasn't bad overall, but I thought the section on what to do when a horse might have been exposed to rabies was worth discussing.

The article asks, "If your client suspects that a horse has been bitten by a rabies-infected animal, what should be done?"

Answer: "Contacting you as the veterinarian is always the first step."

Great first step. A second step that wasn't mentioned should be, "Try to identify and (safely) capture the animal that bit the horse." This is often impossible but certainly worthwhile if it can be done. However, if you're trying to catch the offending animal, make sure you don't put yourself at risk of exposure to rabies in the process. If the animal can be caught, it's rabies status at the time of the bite can be determined (either through testing or quarantine). If it can be shown that the animal wasn't rabid, a lot of stress, hassle and expense can be saved.

"If the horse was previously vaccinated... Then isolate and observe the animal for 45 to 90 days (your clinical evaluation will involve gait analysis, radiography and a spinal tap)."

Boosting the rabies vaccine is also a good idea. The next step, however, needs to be contacting local regulatory officials to find out what you have to do. They determine if, how and how long an animal needs to be quarantined - this is NOT the decision of the local veterinarian nor the animal's owner. Most likely, they will recommend a 45 day quarantine for a vaccinated horse, since this is what is recommended in the NASPHV Compendium on Rabies. The discussion of diagnostic testing makes no sense. There is absolutely no indication to perform diagnostic tests on a horse that has been bitten by a rabies suspect. None. There are no tests that can be used to diagnose rabies in live horses (also exposed horses don't instantly develop signs of rabies). Horses should be monitored closely for signs of rabies during the quarantine period, but that's it.

"...and have the client make a list of all people who had contact with the horse."

This is often done when horses have or are suspected of having rabies, but not horses that are potentially exposed. It is done to help public health personnel contact people that may have been exposed to rabies. A horse that was just bitten by an animal is not a risk for transmission of rabies. (However, keeping a list of people who have contact with the horse after it's been bitten (i.e. durng the quarantine period) - which should be as short a list as possible - is a reasonable precaution in the unlikely event that the horse does develop rabies.)

"If the animal was not vaccinated, your options are to euthanize and perform a postmortem examination of the brain (the only way to definitely confirm rabies)..."

Euthanasia is one of the options that needs to be considered in an unvaccinated horse that has been exposed, which is one of the reasons that identifying the biting animal and testing it is critical, if it can be done. The last part of the above sentence (from the atricle) is complete nonsense. Why would you test the brain of a normal horse that has been euthanized because it's just been bitten by a potentially rabid animal? The horse isn't being euthanized because it has rabies, it's being euthanized because of the likelihood of it developing rabies weeks to months later. Testing of the brain will tell you absolutely nothing if the animal was only bitten recently.

"...or isolate and observe the horse for six months and develop the human contact list."

Again, this needs to be decided based on discussions with regulatory personnel who are responsible for dictating what is to be done. A six-month quarantine is a pretty standard recommendation for an unvaccinated animal. Creating a human contact list should not be necessary, since quarantine involves severely restricting contact of people with the horse and only a few (ideally one) person would have any type of contact.

The article wraps up with the very true emphasis on vaccinating horses. It's a cheap measure to prevent a relatively rare but invariably fatal disease.

Click image for source.

This Worms & Germs blog entry was originally posted on equIDblog on 05-Jan-10.

PInworms and pets

Scott Weese — Tue, 05 Jan 2010 10:25:00 -0500

Pets as a source of pinworms in people (especially children) has been a widespread misconception. A recent article at www.medicalnewstoday.com gives a good overview of pinworms in people and has a nice section about pets.

"Pinworms that affect humans cannot infect animals or pets. However, some microscopic eggs may land on a pet's fur and then be transferred to human hands when stroking (petting). It is important to remember that the problem is not the pet, it is human hand washing and hygiene."

This nicely explains two key concepts:

People are the source of human pinworms.
Hand hygiene is an important routine practice around pets.

Leptospirosis and cold weather

Scott Weese — Mon, 04 Jan 2010 08:34:00 -0500

When we have a -30C windchill and snow on the ground, my first thoughts usually aren't about survival of bacteria in the outdoor environment. However, some microorganisms are well adapted for survival in various adverse conditions and we shouldn't assume that cold=dead for every bug of concern. Along that line, we received a question recently about survival of Leptospira and I passed it along to our lepto expert, Dr. John Prescott. Here's his guest post:

A reader in Ohio owns a dog that had leptospirosis, and had some questions about leptospirosis that may be of general interest.

Q1. Since the yard is likely contaminated with leptospires, she asked “How cold does the temperature have to get before the Lepto organisms are killed?”

A1. Once it’s frozen, as it is now in January, they’re dead. Leptospires are fragile bacteria that are killed by dry heat and by freezing. They survive well in moist or wet environments, with moderate temperatures. In some countries leptospirosis is called “mud fever” or “fall fever” since this description captures so well the environmental conditions under which they thrive.

Although leptospirosis in dogs can occur at any time in the year, it mainly causes disease in the fall, late September to December, peaking in November. The increasingly mild and prolonged falls that we have experienced in the last decade are thought to be an important reason that leptospirosis has resurged in dogs. Interestingly, there is often a “blip” of leptospirosis in dogs in March in Ontario (and likely Ohio), since this is when the snow melts and conditions are wet, even though we can still get freezing at that time. I suspect that this is also the time when the raccoons that are thought to be the main source of leptospirosis for dogs are again active after the winter, and are foraging for food for themselves and their babies.

Q2. Do dogs still shed leptospires after they’ve been treated?

A2. No. Leptospires are quickly killed by the antibiotics used in treatment, amoxicillin or doxycycline. There is no danger that dogs treated for a week with these drugs are a risk to people or other animals. You may read in otherwise very reputable textbooks that these antibiotics “do not eliminate the carrier state” but I have no idea where this misunderstanding comes from.

Q3. Where can I find out more about leptospirosis in dogs?

A3. I like the web site http://www.leptoinfo.com, which is maintained by a vaccine company. I was surprised how many web sites devoted to leptospirosis that there are, but like much on the internet some contain highly misleading information. The “Worms & Germs” site has good past blogs about canine leptospirosis and is usually (just kidding, Scott) a reliable source of information.

One very common entrenched misconception, which is very hard to kill, is that vaccination does not stop animals shedding the organism. This is quite wrong. I suspect this misconception came from an experimental study half a century ago when dogs with pre-existing kidney infection with a leptospiral serovar called Canicola were vaccinated. It would not be expected by anyone that these animals would stop shedding since antibodies don’t penetrate into the place in the kidney where the leptospires live and from which they are shed in the urine. What vaccination does incredibly effectively is to prevent leptospires from actually reaching the kidney and setting up home there. The leptospires are removed by antibodies in the blood, so they never reach the kidney.

Eye protection urged for people with tarantulas

Scott Weese — Fri, 01 Jan 2010 21:45:00 -0500

I've never really understood the appeal of tarantulas as pets. I'm sure there are some people that think they're great pets and I can't really counter with anything beyond "I don't have any desire to have a massive spider in my house." Nevertheless, many people have them. Recently, a rather unusual health concern was reported at medpagetoday.com following publication of a peculiar case report (Norris et al) in the most recent issue of The Lancet.

Hairs on the hind end of the Chilean Rose tarantula, as well as others, have barbed tips. These spiders can release hairs as a defense mechanism. A British tarantula owner was leaning into the spider's terrarium one day when it "doused" his face with a mist of hairs.

When he presented at the ophthalmology clinic three weeks later, his right eye was red, watery, and uncomfortable in bright light. His Snellen visual acuity had degraded to 6/9, versus 6/4 in his unaffected left eye.

Carrim and colleagues reported that initial low-power examination showed diffuse conjunctival injection and multiple corneal subepithelial infiltrates, "visible as scattered white spots."

They initially suspected a viral infection, but higher magnification revealed "fine, hairlike projections" at the center of each spot, with varying depths into the cornea.

At that point, he mentioned the tarantula hair exposure. After 6 months of intensive treatment, his eye problems have greatly improved, and he now wears eye protection around the tarantula.

It's unclear how common this is. There have been other reports of this problem and certainly there must have been other unreported cases. Overall, it's probably rare for tarantula owners to be affected but it seems like a pretty nasty problem and one you'd want to avoid. Pets like tarantulas often come and go in popularity, and any upswing in tarantula numbers could result in more eye injuries. People need to be aware of this problem if they own, or are thinking about acquiring, a tarantula. Animal exhibits that have tarantulas and any other places where tarantulas may be present (e.g. schools) need to think about this as well. Wearing eye protection when handling these spiders in close quarters, keeping your face of the terrarium, avoiding stressful situations that might make the tarantula release hairs, good handling skills and restricting close contact seem like logical and practical measures to reduce the risk.

Image: Chilean Rose tarantula (source: www.wikipedia.org)