In response to an equine herpesvirus type I (EHV-1) outbreak at Hawthorne Racecourse in Illinois, the Ontario Racing Commission (ORC) announced movement restrictions on horses from Hawthorne, and Illinois in general.

Effective immediately:

  • Any horse that has been on the grounds at Hawthorne since Oct 4 is not allowed on any Ontario racetrack until 30 days after Hawthorne’s quarantine is lifted
  • All horses from Illinois being shipped into the Woodbine or Fort Erie racetracks must come with a certificate that states "Horses represented on this Certificate of Veterinary Inspection have not originated from a barn or premises that is under quarantine for herpes virus, nor have been exposed to a confirmed or suspect case of herpes virus, nor have shown clinical signs suggestive of herpes virus, nor have been febrile within the previous three weeks."

All other tracks are also advised to be cautious about accepting horses from Illinois, but restrictions are at the discretion of individual facilities.  The ORC is also recommending that all horses from Illinois are examined and their temperatures are taken prior to being admitted to any track.

Basic physical examination and body temperature checking can be great infection control measures when used on a routine basis. Too many sick horses make it onto tracks, show grounds and into sales, and while checking temperature is by no means 100% protective, it’s an easy, cheap and a quick way to identify potentially infectious horses. Yet, it doesn’t happen. Considering the potential implications of a single infectious horse making it onto a track, it doesn’t make sense that more effort isn’t put into routine practices like these. Yes, it would take a couple minutes, but if it prevents one infection (let alone an entire outbreak), it’s worth the minimal effort.

As an aside, I’ve always been baffled why places like yearling sales won’t consider employing such measures –  well, maybe not baffled because sending sick horses home costs the sale money.  But considering how common infectious diseases are in horses after sales, it’s hard to understand why buyers are not pushing sales to do what they can to make sure buyers aren’t spending big money on damaged goods, i.e. sick horses. I’d like to think that a sale could make it a great marketing point by touting their strong infection control program to convince buyers to come and spend their money with less chance of getting a sick horse.

It’s always hard to say what the best approach is for handling EHV infections. On one hand, it’s a very common virus that is lying dormant in the bodies of a large percentage of healthy horses, everywhere. On the other hand, we certainly know outbreaks of serious disease happen and horse-horse contact and movement of horses helps outbreaks spread. These Ontario restrictions are pretty straightforward and common sense, but thought should be given to what other measures can be taken on a routine basis to help reduce the risk of EHV-1 outbreaks from developing in Ontario, and to control the numerous other infectious diseases that affect more horses every year.

In the latest edition of the American Animal Hospital Association’s Trends magazine, there’s an article about veterinary clinic design. The section dealing with exam rooms says:

Discussion is ongoing about whether sinks are needed in the exam room now that hand sanitizers are available.

  • I’m not sure who’s discussing this. Hand sanitizers are great and should be used as much as possible, but that doesn’t mean handwashing is obsolete. Some pathogens we deal with are resistant to alcohol, such as parvovirus, Clostridium spores and ringworm. We need to wash hands when these bugs might be present. Hand sanitizers also don’t help if you have chunks of pus, blood or feces on your hands. If there’s no sink in the exam room, handwashing usually won’t be done when it’s supposed to be. If someone has to leave the room and walk to a sink, it just doesn’t happen often, even if it’s a short distance. A person also runs the risk of contaminating other surfaces along the way, between the exam room door and the sink.

Experts agree, however, that if you have a sink, your clients will expect you to use it to wash your hands.

  • I’m not sure who these experts are, or what they’re experts in. Certainly not common sense or infection control. What they’re implying here is that pet owners will think veterinarians aren’t doing a good job if they see a sink and the vet doesn’t use it, but that if no sink is present, no one will think twice about a vet failing to practice good hand hygiene. If an owner is going to clue in to the presence of the sink and failure to wash hands (something we should be encouraging), their common sense and observation skills won’t evaporate if there’s no sink.

This is similar to an interview with an architect on dvm360.com where the guy says "if I have a sink I better wash my hands or the client thinks my hands aren’t clean. In many cases it’s better off not to have a sink…" (note: the banging you hear is me hitting my head against a wall). The same architect cited in this article, so hopefully he’s actually the only one pushing this approach.

Pet owners aren’t dumb.

Infection control isn’t rocket science.

Handwashing is important and under-used.

We need sinks in exam rooms.

Common sense needs to be more common.

It’s difficult to put sinks in existing exam rooms – some clinics just can’t do this easily. That’s tolerable if they are diligent in their infection control practices, use hand sanitizers as appropriate and make sure they get to a sink (without contaminating things along the way) when they need to wash their hands.  Not putting sinks in a newly designed clinic is just dumb.

People sometimes get freaked out by the concept that they have approximately 10-times as many bacterial cells on them as all their own body cells combined.

  • Yes, our cells are a minority in our own bodies, and amongst the trillions of bacteria we carry are many that could kill us given the opportunity.

Yet, we have somehow managed to survive, both individually and as a species. So, keeping things in perspective is important and, in reality, we need much of that bacterial population to keep us healthy.

Just like every person is carrying many bacteria on any given day that can cause illness or infection, every animal is carrying many different microorganisms that can infect a person. While infections from pets do happen, they are uncommon – we’re not seeing dog owners dropping like flies on the street, which is a testament to our immune system and other body defenses and barriers (e.g. intact skin).

So, when studies come out describing various bugs at various sites in various animals, you have to put them into context. It’s not that the studies are bad (my lab does a lot of work trying to define the complex bacterial populations of sites like the intestinal tract, oral cavity, respiratory tract and skin), it’s that we need to think about what the results really mean and avoid sensational headlines in the press.

A recent paper in the Archives of Oral Biology (Yamasaki et al. 2012) is an example of this. The study looked at mouth bacteria in dogs and their owners. They used molecular testing developed for human oral samples and focused on bugs that have been implicated in dental disease – not the range of bugs that are more often associated with zoonotic infection. Not surprisingly, they found lots of different bacteria in the mouths of the dogs, including some bacterial species that were present in both dogs and their owners. No methods were used to type the bacteria to see whether the strains found in dogs and people were the same or whether dogs and people just normally have those bugs present, independently, in their mouths. However, we know that transmission of certain bacterial between people and their pets is a relatively common event, and it wouldn’t be surprising if the same applies for oral bacteria, through direct contact (e.g. kissing/licking) or through indirect contact (e.g. a person touching a dog’s face then his/her own face).

So, this was an interesting study… nothing earth-shattering but the first side-by-side comparison of oral microflora in people and dogs, and it provided some useful information for future research. The authors rightly discuss the limitations and things that need to be done to further investigate this, such as looking at strains and evaluating the bacterial population in relation to types of contact that people and dogs have (e.g. do certain activities increase the likelihood that people and pets share oral bacteria). They conclude by writing "In summary, we found that the distribution of periodontopathic bacterial species in dogs and their owners is diverse, though several species including P. gulae may be transmitted during close daily contact. Therefore, our findings could be significant in understanding the relationship between the oral health of humans and their companion animals"

Yet, headlines like "New study warns against kissing your dog" don’t really reflect the true content… not uncommon but unfortunate.

I get asked about dogs licking a lot. My general line is that I don’t particularly like to be licked but for the average healthy person, I don’t get worked up about it. My kid were playing with puppies yesterday and were getting licked. I didn’t fire up the power washer to hose them down after. If I had an infant, an immunocompromised child or some other high risk person it would be a different story.  Licking around the ears is something I like to see avoided because of some links between this activity and certain ear infections in kids, but overall it’s a relatively low risk situation that some people enjoy.

When I give talks about methicillin-resistant staphylococci, I almost invariable get into a discussion of the risks of methicillin-resistant S. pseudintermedius (MRSP) in people. This bug is becoming increasingly common in dogs and because it’s so resistant to antibiotics, there’s concern about whether it can be transmitted to people.

My usual answer is that there is a low risk of MRSP infection in people, but not no risk. MRSP is no more likely to cause an infection in a person compared to it’s antibiotic-susceptible counterpart, regular S. pseudintermedius (the resistant version is just harder to treat). Most dogs carry susceptible S. pseudintermedius in their mouths, nose, skin, ears and/or intestinal tracts, so people in contact with dogs are very commonly exposed. Yet, human infections seem to be quite rare. There are periodic reports in the medical literature about S. pseudintermedius infections in people, but they tend to be single case reports, and when someone can publish a report of a single infection in person, you know it’s pretty uncommon (since if it was common, no journal would be interested).

That’s my long-winded way of introducing a recent case report in the Journal of Clinical Microbiology (Hatch et al. 2012). The patient in the report was an elderly man with underlying disease, so someone who was at high risk of infection from bugs that don’t often affect otherwise healthy people. He had skin lesions, sore joints and a bloodstream infection, and "S. intermedius" (I’ll get to the name issue later) was isolated from his blood. Fortunately, he was successfully treated. He owned a dog and that was (reasonably) considered to be the source of the bacterium, but no testing was done to look into that. So, from a disease standpoint, it’s not really a surprising case – just another in a series of very rare infections that have happened.

The other issue here is the fact that the authors (along with the diagnostic lab, the journal’s reviewers and the editor) are behind the times and don’t realize that it’s virtually guaranteed that this person didn’t have a S. intermedius infection. Rather, it was presumably S. pseudintermedius, or perhaps another similar staphylococcus. It wouldn’t have much of an impact on this particular case, although not knowing the species probably also indicates the lab doesn’t know that there are different breakpoints to determine if the bug is methicllin-resistant, and there’s the potential they would miss methcillin-resistant S. pseudintermedius and use an inappropriate and ineffective treatment (fortunately that didn’t happen here).

I’ve had a few (well… more than a few) calls about potential risks to animals from the large Canadian E. coli O157 beef recall. The main concern is for dogs that are fed potentially contaminated raw meat that has been recalled, but there is also potential for exposure through cross-contamination if people in the household consumed any suspect products, and through dogs getting into garbage containing meat packaging. The other issue is whether dogs and cats can become exposed, start shedding the bacterium in their feces and subsequently infect people. Contamination of a pet’s food bowl leading to human exposure is also a potential concern, especially considering the fact that as few as 10 of these E. coli bacteria can cause infection in people.

Overall, these risks are quite low. The contaminated meat is primarily a human concern. The role of E. coli O157 in disease in dogs is pretty unclear, but there’s no evidence it’s a significant problem. Experimentally, disease can be induced in dogs fed relatively high numbers of E. coli O157, but natural disease seems to be rare (including in dogs on beef farms where exposure is probably relatively common). I think it’s reasonable to suspect that this strain of E. coli can cause disease in dogs, but it doesn’t happen very often. We also don’t recognize hemolytic/uremic syndrome (HUS) in dogs (the severe form of E. coli O157 infection that can cause kidney disease in people).

The risk to people from recalled meat is real. The risk to people from pets is pretty remote. Studies have not identified pet contact as a risk factor for human E. coli O157 infection. Dogs have been implicated as vectors in a limited number of specific household situations, albeit with rather weak evidence and only when focused on people and animals on beef farms.

Overall, the risks to pets and from pets are pretty limited. The main concern with the recalled meat is human disease. That being said, I wouldn’t recommend people feed recalled meat to animals instead of disposing of it, since there is a possible though slight risk to both humans and animals.

A Wyoming (USA) dog has died of necrotizing fasciitis (more popularly and dramatically known as "flesh-eating disease"). This isn’t unheard of in dogs, but it’s a pretty rare disease. The six-year-old Great Dane’s infection apparently raised some concern because of the diagnosis of necrotizing fasciitis in three people in the area. However, there is no known connection between the dog and the human cases.

While not anything new, the case is noteworthy for a few reasons, not the least of which is the high mortality rate associated with this disease. A few different types of bacteria can cause "flesh-eating disease," but streptococci are most common. The news reports say the dog had Group A strep, which is quite surprising and raises a lot of questions, such as:

  • Was it really Group A strep? Most of these infections in dogs are caused by a related bug, Streptococcus canis, which is a Group G strep. Group A strep is essentially unheard of in dogs and I have to wonder whether the bacterium was misidentified by the lab or the reporting is inaccurate.
  • If it actually was Group A strep, what’s the public health concern? Group A strep is a common bug in people (the one that causes strep throat) but invasive infections like necrotizing fasciitis are a much bigger concern, and potential dog-human transmission would have to be considered.
  • If this was Group A strep, are public health authorities taking the same steps was they would in response to finding Group A strep necrotizing fasciitis in a human in the household (such as the Public Health Agency of Canada’s Guidelines for the Prevention and Control of Invasive Group A Streptococcal Disease?) This would make sense to me.
  • If this was really Group G strep (the most likely scenario), did the dog receive a fluoroquinolone antibiotic before the infection set in? It doesn’t sound like that was the case from the article, but knowing for sure would be interesting. Most cases of Group G strep necrotizing fasciitis that we see are associated with enrofloxacin treatment of an initially mild infection, since this drug can induce increased virulence in Group G strep.

Regardless of whether it was Group A or Group G strep, it’s an unfortunate situation for the dog and the family, but people shouldn’t be too concerned because this is a very rare, sporadic disease in dogs and one that has not been linked to any risk to other species.

Earlier this year, a troop of Boy Scouts in the US beat off a rabid beaver that was attacking their leader (I wonder if there’s a badge for that). Boy Scouts and infectious diseases are in the news again, but not with as happy a story.

In the recent incident reported on ProMED, ten Boy Scouts that attended a camp on the banks of the Semois River in Belgium developed leptospirosis – a potentially severe bacterial infection caused by Leptospira bacteria. The bacteria are shed in the urine of a variety of animal species, and people can become infected through contact with contaminated water or animals. The boys reported having played with a rat, which was likely actually a muskrat, based on the description of its size.

Three of the boys were hospitalized.  Hopefully all are on the way to recovering.

This is yet another reminder that wildlife should be left alone. It’s possible the boys were infected from the environment, but handling a muskrat (which was presumably sick if they were able to get that close to it) certainly increases the risk of exposure to a variety of infectious diseases.

Image of a North American muskrat (photo credit: Linda Tanner)(click image for source)

It’s perhaps a good sign for public health when I don’t tend to come home from a local fair and write a rant about the sorry state of the petting zoo. Around here, things seem to have improved at most events over the past few years, probably largely because of the efforts of local public health personnel. However, some establishments still fall through the cracks and regardless, even with optimal management, there’s always some degree of risk with contact between animals and the public.

Welsh authorities are investigating a small (so far… and hopefully to remain that way) outbreak of E. coli O157 that has been tentatively linked to Cantref Adventure Farm. The two children became ill after visiting the farm. Two family members of one child have also tested positive for the bacterium, and it’s believed that one of them was infected via contact with child (as opposed to direct contact with animals at the farm). Since both kids visited the farm in the days before they got sick, and since petting zoos are a prime source of E. coli outbreaks, it’s logical to assume the farm was the source. Even though this has not yet proven, the reason to make this early assumption before a link can be definitively established is to get the word out to others that may have visited the petting zoo, in case there are more cases of illness. Authorities are telling people who visited the farm since the beginning of August to contact their physician. It’s not clear whether they want to test everyone (by collecting a stool sample) or just have them checked out to make sure they are okay.

Meanwhile, the investigation at the farm is ongoing. Presumably, stool samples from animals on the premises and environmental samples have been collected to see if the same strain of E. coli is present. All direct contact between the public and animals on the farm has been stopped, and the site is being thoroughly cleaned. That’s a pretty standard response overall, and hopefully if the petting zoo was the source, transmission has ceased.

Petting zoos can be fun and educational and we don’t want to over-react and assume they are all inherently dangerous. There’s always some degree of risk of infectious disease exposure, and the key is making sure petting zoos are run optimally to reduce, as much as possible, the risk to the public. The public also has to play a role, by following rules, supervising children and (probably most importantly) actually using hand sanitizers and handwashing stations that are provided.

.Dirofilaria immitis is the parasite that causes heartworm in dogs (and rarely cats). This mosquito-borne parasite can cause serious disease in dogs, and a lot of effort is spent trying to prevent heartworm infection. It can also cause disease in people who are bitten by a mosquito that has fed on an infected dog, but human infections are quite rare and of limited health risk. The main concern with regard to human infection is that it can create a small mass in the lungs. The mass itself isn’t usually a problem, but if it gets seen on an x-ray, it may appear very similar to a lung tumour, potentially leading to the use of more invasive diagnostic techniques (e.g. lung biopsy) to rule out cancer.

Dirofilaria immitis is not the only species of Dirofiliria. In fact, there are mulitple different Dirofilaria species with different hosts, some of which can also rarely infect people.

When it comes to dogs, D. immitis is the main concern, but dogs are also the host of Dirofilaria repens, which is most common in Mediterranean countries, eastern Europe and sub-Saharan Africa. Now, there’s a new one to add to the list, based on a paper in the Journal of Clinical Microbiology (To et al. 2012) that describes a novel Dirofilaria species in Hong Kong. Interestingly, it was found first by identifying disease in people.

Three human cases were identified in Hong Kong over a 10 month period in 2011-2012. When the researchers recovered the parasite from these individuals, they determined that, while it looked like other Dirofilaria, it was genetically different from any known species. They have tentatively named it «Candidatus Dirofilaria hongkongensis» (not very original but descriptive).

They then tested blood samples from 200 dogs and 100 cats, and found a parasite in six dogs that was identical to the new Dirofilaria from the human patients. They also tested the dogs with a commonly used commercial heartworm test that detects D. immitis and they were all negative, except for one dog that was actually infected with both the new species and D. immitis.

This is an interesting report and shows the need to be aware of potentially emerging issues. Some important questions need to be answered:

  • What’s the risk to people? Obviously it can cause disease, since the three people in this report were actually sick. However, is this a very rare condition or something that may be more common? Is it something that’s been around for a long time and not diagnosed or is it really new?
  • How do people get infected? They presumably get it from being bitten by an infected mosquito (as for other Dirofilaria) but how does the mosquito get infected? Are dogs the main source, one of many sources or are they inconsequetial?
  • Does this new Dirofilaria cause disease in dogs? The six positive dogs were healthy, at least at the time of testing. Heartworm caused by D. immitis is a gradually progressive disease, meaning the signs become worse over time, so the fact that these dogs were clinically normal doesn’t mean there’s no risk, as they could start showing signs later on.
  • What is the risk outside of Hong Kong? It’s hard to say because we know so little about this parasite, but it’s probably limited, at least at this point in time.

 (click image for source)

I’ve written about lymphocytic choriomeningitis virus (LCMV) before, as an interesting but pretty uncommon rodent-associated disease. Human infections are mainly associated with handling  rodents, although other routes of transmission, such as organ transplantation from an infected donor, have also been reported. Being a disease associated with rodents and considering how rodents are produced in North America (i.e. mass production in large breeding colonies, followed by transportation to large distributors and massive mixing of animals), LCMV is bound to be a recurring problem associated with the pet rodent trade.

An issue of the CDC‘s ominously titled Morbidity and Mortality Weekly Report describes the risk of infection with LCMV to people who work in rodent breeding facilities. It all started with the diagnosis of meningitis in a person who worked in a rodent breeding facility in Indiana. An astute doctor suspected LCMV and the diagnosis was confirmed. The breeding facility was a pretty large one, housing approximately 155 000 (!) mice and 14 000 rats. An investigation of facility personnel ensued and approximately 25% of employees had antibodies against the virus, indicating previous infection. A large percentage of the workers reported having had signs consistent with disease (e.g flu-like illness), indicating that they were likely infected and not just exposed.

Considerable effort was put into testing the animals.  Of over 1000 animals tested, 21% of mice had detectable levels of the virus in their bodies. That’s pretty impressive and concerning, both for employees and anyone receiving animals from this facility.

In response to this investigation, all mice at the facility were euthanized, and the facility was thoroughly cleaned and disinfected.

This report highlights the risk of exposure to LCMV for people who work with rodents, especially in large facilities such as this. It also highlights the risks posed to people buying rodents from these facilities, which also includes other diseases in addition to LCMV. Good general hygiene and infection control practices should greatly reduce the risk of LCMV transmission to rodent owners. In particular, efforts should be directed at new rodents, since LCMV shedding is probably greatest during the initial period after an animal enters a household or other facility. Virus shedding it often transient, and once they get out of the high-risk facility and become acclimatized to their new home, shedding rates in these rodents probably decrease over a short period of time. Overall, the risk of LCMV in someone with a pet rodent is low, but these basic preventive practices are easy to do and make a lot of sense.

Photo: Female mouse with her litter. (Photo credit: Seweryn Olkowicz) (click image for source)