Scott Weese
Scott Weese is an Associate Professor in the Department of Pathobiology at the University of Guelph, and Public Health and Zoonotic Disease microbiologist for the University's Centre for Public Health and Zoonoses. After graduating with a Doctor of Veterinary Medicine degree and spending time in private practice, he completed an large animal internal medicine residency and Doctor of Veterinary Science graduate program. He is board certified in internal medicine by the American College of Veterinary Internal Medicine and is Chief of Infection Control at the Ontario Veterinary College Teaching Hospital. He has an active research program focusing on infectious diseases, particularly those that can be transmitted between animals and people. He lives outside of Guelph, Ontario with his family and a collection of pets, including a dog, cat, fish and a herd of rare-breed sheep.
Dog cull considered in Israel
Israel has experienced a major upswing in canine rabies cases since 2009. There had been a significant decline since 2003, when oral rabies vaccination of foxes was started, but the recent increase has been in dogs and jackals, not foxes. Now, stray jackals and dogs are the main rabies vectors in northeastern Israel, the area affected by the current outbreak.
Stray dogs are a significant concern in terms of rabies because they can have close contact with humans and wildlife. Dogs are the most common source of human rabies internationally and thousands of people die each year from rabies acquired from dogs.
The increase in rabies in stray dogs and jackals has lead to discussions about how to control the stray population and reduce the risk of rabies. Previously, it was common for authorities to shoot strays in parks and nature reserves. This practice was stopped a while ago, however the Israel Nature and Parks Authority has now asked for permission to shoot strays in the interest of rabies control. The proposed regulations would allow strays to be shot in national parks, reserves, and "any other open area where wildlife species are considered at risk", but not unless their presence poses "an immediate discernible risk to wildlife and never within 1 km of human habitation."
This seems to be a wildlife protection program disguised as a rabies control program. The emphasis is on protection of wildlife, since packs of stray dogs have had major impacts on some endangered wildlife (e.g. fallow deer). It's not really a good rabies control program, since culling alone is unlikely to be effective, and only culling when the dogs pose a risk to wildlife and away from human habitation presumably would only have a limited impact on the prevention of human rabies. If they want to control the dog population to protect endangered species, they should just say that. If they want to control rabies, they need a comprehensive rabies control program that involves consideration of various approaches such as vaccination of strays and jackals, sterilization of strays, public education to decrease the risk of exposure, and vaccination of domestic animals. A cull alone won't cut it for rabies control.
Photo: A pair of Golden Jackals (Canis aureus) in Israel (photo credit: Michael Baranovsky)(click for source)
Leptospirosis in Michigan
Veterinarians are reporting an apparent spike in cases of leptospirosis in dogs in southern Michigan. Leptospirosis is considered a re-emerging disease in many areas of North America. This disease, caused by various types of the Leptospira bacterium, can affect many different species, including dogs and people. A wide range of illnesses can result, including fatal infections. In dogs, kidney failure is a common problem.
Classically, leptospirosis is diagnosed in dogs that spend time in the woods and similar areas, where they may be exposed to the bacterium from contact with the urine of infected wildlife. Different types of Leptospira have different animal hosts, and infected hosts can shed large numbers of bacteria in urine. These bacteria can survive in wet conditions for long periods of time, and other animals can be infected through ingestion of urine-contaminated water or contact of urine-contaminated water with broken skin (e.g. tiny cuts or open sores on their feet) or mucous membranes (eyes, mouth, nose).
Michigan vets have suggested that the recent spike in cases is the result of local highway construction, which may have driven rats out of their normal habitats and into areas that people and dogs frequent. That's possible, but it could also be increasing natural re-emergence of the disease, or increasing recognition of the disease, as more attention is being paid to it. Regardless, an understanding that this disease is a problem in the area is important to allow for prompt diagnosis (and proper treatment), as well as preventive measures.
A vaccine is available, but it is not 100% protective and only protects against certain strains of Leptospira. Nonetheless, it's still a good idea in areas where disease is caused by the strains present in the vaccine and when dogs have a reasonable chance of being exposed.
People can also get leptospirosis. Most often, they are exposed just like dogs: from the outdoor environment. However, pet-to-human transmission has been reported, mainly involving pet rats (since rats are an important reservoir host). People who have contact with an infected dog must take precautions to reduce the risk of transmission. This includes avoiding contact with urine, good attention to personal hygiene (especially hand washing), and proper cleaning and disinfection of any areas potentially contaminated with urine. Prompt diagnosis of canine lepto is very important because treatment rapidly stops the animal from shedding the bacterium. The earlier it's diagnosed, the quicker it can be treated, and the less contamination can occur.
More information about leptospirosis and Leptospira is available on the Worms & Germs Resources page, and in our archives.
Tiger smuggler thwarted
Security screeners at a Thai airport discovered an attempted tiger smuggling, presumably by realizing stuffed animals don't have a skeleton. A 31-year-old Thai national was trying to smuggle a sedated tiger cub in a carry-on bag. As it went through the X-ray machine, screeners noticed an item resembling a real cat. Closer inspection identified the actual item and the individual was arrested.
Unfortunately, this person is presumably among the very small minority of smugglers that actually get caught. Creative smugglers, established smuggling pathways, lucrative markets and extremely lenient penalties combine to make this a pathetic but unfortunately often profitable venture that results in the deaths of huge numbers of animals, and acts as a potential way to transmit various infectious diseases that could affect other animals or humans.
Image: Tiger cub at the Philadelphia Zoo (source: http://commons.wikimedia.org)
Human rabies death in Louisiana
A field worker from Mexico died in Louisiana this weekend from rabies. This is the first case of human rabies in Louisiana in over 60 years, but based on the time the man had been in the country and the incubation period of rabies, it is believed that he was infected in Mexico. Human-to-human transmission of rabies is rare, but healthcare workers and other people he had recent contact with are being evaluated to determine if post-exposure treatment is required. In the case of the man's co-workers, they could have also been exposed to the same source of rabies that infected him.
The original source of infection isn't known, or at least has not been reported. Wildlife are the main source of rabies exposure for people in the US, but dogs are the most common source of human infection internationally. Dog-associated rabies cases in people from Mexico have been previously reported in the US, and it's certainly possible here.
Rabies vaccination requirements
I periodically get questions about whether rabies vaccination is really required or if it's just a good idea. There's not a straight answer because legal requirements vary by region. In Ontario, Regulation 567 of the Protection and Promotion Act states that all dogs and cats three months of age or older that reside in specified areas of the province must be vaccinated. Further, animals must be revaccinated by the date specified on the certificate of immunization. Basically, this means that all dogs and cats must be vaccinated and they must be up-to-date on the vaccination, based on the type of vaccine that was used.
Even if vaccination isn't legally required, if rabies is in an area, it's a good idea because:
- If a pet gets rabies, it will die.
- If a pet gets rabies, owners or other people in contact with it may need post-exposure treatment.
- If a pet gets rabies, it could infect people with this almost invariably fatal disease.
- If an unvaccinated pet gets exposed to rabies, it will need a strict 6-month quarantine or euthanasia. (Euthanasia is common in these situations.) If the pet was vaccinated, all it needs is a 45 day home observation.
Rabies vaccination of pets is easy, cheap and safe, and often required by law.
Image source: http://amcny.wordpress.com
Mass rabies exposure from raccoon
Yet again, a large number of people are undergoing rabies post-exposure treatment because they were exposed to a rabid raccoon that was "adopted" from the wild. In this case, a North Carolina family found a baby raccoon at the side of the road and decided to bring it home. Over the next couple of weeks, various family and friends handled the raccoon, and many were bitten or scratched in the process. The raccoon then died and was identified as being rabid. Forty-five people are now being assessed to determine whether they need to be treated for rabies exposure.
The family dog, which was unvaccinated, has been taken by Animal Control and now faces either a six-month strict quarantine or euthanasia. I suspect the dog will be euthanized.
So, this probably well-meaning but misguided action has resulted in:
- the need for costly post-exposure treatment of many people
- presumably a stressful period for many of those people
- probably the death of the pet dog (although not having the dog vaccinated played a big role here too, since if it was vaccinated, it would only face a 45 day observation period at home, not a strict six-month quarantine or euthanasia).
Fortunately, the raccoon was tested. Otherwise we might be talking about human deaths from rabies, instead of people needing post-exposure treatment. The people who took in the raccoon could also face charges since keeping wildlife without a permit is illegal, but it sounds like that's unlikely to occur.
A few take-home messages from a situation like this:
- Leave wildlife in the wild.
- Vaccinate your pets.
- If you are exposed to an animal that is acting strangely, make sure it's tested for rabies (they did this right, at least).
Toddler risks losing eye to dog parasite...maybe
A few UK news outlets published a story the other day about a toddler with a severe eye infection that was attributed to Toxocara canis, the canine roundworm. Some parts of it didn't make a lot of sense so I held off commenting, but the story's spreading more widely now so I might as well raise a few issues.
The story is about a toddler that fell into a pile of dog feces while playing at the park, then wiped her eye. Her mother took her right home and washed the eye out. Then, according to the BBC:
"She woke up in the early hours screaming and her eye was bright purple and red and swollen shut with the eyelashes inside. She had a temperature and was very lethargic and in a lot of pain." Hospital tests confirmed toxocariasis, which resulted in Amiee contracting optical lobe cellulosis, which can lead to blindness and death if not treated within 72 hours.
Here's where I start to get confused. Eye infections are one problem cause by Toxocara canis. However, the disease (ocular larva migrans) develops when someone ingests infectious T. canis larvae from feces. It takes a few days to a few weeks after being passed in feces before the larvae become infective, so this would have to have been a pile of old feces (something that's certainly possible).
Nonetheless, as I said, ocular larva migrans develops when someone ingests the larvae, which then migrate out of the intestinal tract, journey through the body and end up in the eye. This doesn't happen in a few hours, as is described here. It takes much longer. Even if infective T. canis larvae were injected in the eye, you wouldn't see the type of severe inflammation around the eye that is shown in the picture on the BBC website. Fever is also rarely present with ocular larva migrans. The parasite gradually causes inflammation within the eye, not around it.
The girl is being treated with 3 antibiotics and an eye ointment. Again, this makes no sense for toxocariasis, since it's a parasitic infection within the eye. Antibiotics aren't going to be useful.
The rapidity of onset, the involvement of tissues around the eye, the presence of a fever and the reported treatment suggest to me that this is actually a bacterial infection of the eye and surrounding tissues, something that certainly could be related to the multitude of bacteria present in dog feces.
Regardless of the cause, the notion that dog owners need to be responsible and clean up after their dogs remains. Let's hope the physicians know what's going on and are treating Amiee properly.
What not to do in a vet's office
TheNorthwestern.com has an interesting article about "10 things not to do with pets in a vet's waiting room." They're all good points, and I've put an infectious disease/infection control spin on them below:
1. Don’t fail to contain your cats. Even if your cat is the sweetest thing on record, some other animals may not agree. The last thing we want is to see in our lobbies is an altercation in which one animal dies. Cat carriers are cheap and widely available. Use them.
2. Don’t give dogs free reign. Don’t use retractable leashes!
- You wouldn't (hopefully) go into an emergency room and lick the face of the person puking in the corner or the kid hacking up a lung. Your pet's not as discriminating. Some pets are at the vet because they are sick. You don't want your pet to get what some other pet has. Also, not all dogs and cats are social, especially in a strange environment. You don't want to change your vaccination appointment to a "vaccinate and stitch up the big wound on my dog's face" appointment.
3. Don’t bring in animals you cannot personally control.
- As above. Lack of control equals increased risk to other animals, your animal, and potentially other people.
4. Don’t do the puppy park meet-and-greet thing. The vet’s is not the dog park. It’s a strange environment in which pets don’t always act the way you expect them to. Moreover, in a veterinary hospital the onus is on the doctor’s staff to keep your dogs safe. Please keep all pets apart. After all, no matter how well you know your pet, can you honestly say you know someone else’s?
- Same as above. More mixing and more contact equals a greater risk of disease transmission. That's acceptable in many situations where the risk of coming into contact with an infectious animal is low, but the odds are higher in a place where sick animals congregate.
6. Give the cell phone rest. In a place as potentially anxiety provoking as the vet hospital, cell phones can be a hazard. Even if you don’t feel the anxiety, your pet certainly does. She deserves the comfort of your undivided attention for her safety and her stress level.
- Not really an infectious disease issue but it's annoying.
7. Don’t walk a dog into a packed waiting room. If the lobby is crammed wall to wall with pets, don’t chance it. Ask someone to let the receptionist know you’re waiting outside. Or use your cell phone for something really useful for once.
- Good point. I'd take that a step further. Don't take a potentially infectious pet into a waiting room, packed or not. If you have an animal that might have an infectious disease (e.g. diarrhea, sudden onset of coughing and/or sneezing) it would be ideal to call when you arrive so they can take your pet right back to an exam room or isolation for examination. That way, if your pet is infectious, you won't expose other animals. We're trying to get more clinics to be proactive about doing this, and hopefully your clinic would mention it, but if they don't, feel free to bring it up yourself.
8. Don’t fail to tell the receptionist ahead of time if your pet is severely anxious or aggressive. All hospitals appreciate the warning when you make your appointment. It gives us a chance to offer you back-door alternatives or other concessions to your pet’s unique behavior issues.
- Good point. "If your pet is severely anxious, aggressive or might have an infectious disease" would be better.
9. Don’t bring small children unless you can’t help it. A busy animal hospital is tough on small kids. They’re not old enough to benefit enough from the educational experience relative to their risk of getting hurt.
- Sometimes you have to, but if you can avoid it, that's preferred. Vet clinics can be busy. There are a lot of animals around and it may be hard for a child to resist reaching out for another animal. I haven't seen any data on bites and scratches in waiting rooms, but they certainly occur. As well, if you are distracted by your child, you may not be able to tell your vet all the relevant information or ask all the questions you have.
10. Don’t be rude. Courtesy is king. Kill them with kindness. I shouldn’t have to offer so many versions of the same cliche, but the fact that they all exist is fine testament to their utility.
- Again, not necessarily an infectious disease concern, but really being polite and considerate to those around you applies to just about any situation, and generally makes everyone feel better and makes things go smoother.
Clostridium difficile and hospital visitation dogs
A couple questions that I received about C. difficile and hospital visitation dogs:
Is there any concern about cross contamination from dogs/handlers that visit health facilities and get contaminated by C. difficile? I see on this site a concern about dogs being contaminated by visitation and I wonder if the Delta Society has considered this to be an acceptable risk.
Dogs (and handlers) could be sources of C. difficile in hospitals. We have shown clearly that dogs that visit hospitals are at increased risk of shedding C. difficile in their feces, presumably because they ingest C. difficile spores from the hospital environment and/or patients' hands. All dogs that go into hospitals are at risk, with dogs that lick patients and that are allowed up on beds at increased risk (Lefebvre et al 2009). We have also shown that the dog's body can become contaminated with C. difficile after visiting a hospital.
Should there be a period of time mandated between visits to account for possible contamination?
That's hard to say, but probably not. Contamination is a potential problem and certainly occurs, but we don't know how long it lasts nor whether providing a "rest" period actually does anything. Clostridium difficile spores, the form of the bacterium that would be present on a dog's coat, are very environmentally tolerant and can survive for years. Therefore, giving a few days break in between visitation would not result in the bacteria dying. However, some spores would presumably be physically removed over time, through shedding of hair, grooming and other activities. Based on that, it's plausible that the longer the time between visits, the less likelihood of contamination still being present. Whether this actually helps, we don't know.
What to do?
Among other things, we need to consider whether there is actually any evidence of risk. We don't know whether dogs are able to transmit C. difficile in hospitals. My assumption is that there is some degree of risk, but it's limited and can be controlled with good hygiene and the use of basic visitation practices, as highlighted in the "Guidelines for animal-assisted interventions in healthcare facilities" (American Journal of Infection Control, 2008).
Another thing to consider is whether there are any measures that can be taken to reduce potential risks, while maintaining a practical and effective visitation program. A key component of this is knowing that there are factors that make it more likely that a dog will be exposed to C. difficile during visitation. If a specific subset of dogs is at increased risk, then you have a clearer way to approach it. In this case, dogs that are allowed to lick patients and that are allowed on beds are at increased risk. These activities are modifiable - you can prohibit them without having a significant impact on the visits. Licking can be prohibited. Dogs can be kept off beds unless it is required, and when that's the case, they can be placed on a towel or some other barrier to reduce their exposure to C. difficile from the bed. Additionally, we know that if a dog is being treated with antibiotics, it's more likely to shed C. difficile, so dogs that are being (or have recently been) treated with antibiotics should be excluded from visitation.
For C. difficile to be a problem, it has to go from human or animal feces to a patient's hands and then to a patient's mouth. There are multiple potential interventions to interrupt this chain of transmission. At the end of the day, however, hand hygiene is the key. If people wash their hands before and after touching the dog, there should be much lower risk of disease transmission. A problem is that when I say "hand washing," I mean hand washing - not use of an alcohol-based hand sanitizer. Clostridium difficile spores are resistant to alcohol. That creates a conundrum because the use of alcohol hand sanitizers, a common and recommended hand hygiene method, doesn't have the ability to kill C. difficile. Since not all visitation patients are able to get up and go to a sink, that complicates C. difficile control.
Plague in Saskatchewan
Plague has been identified in a dead prairie dog in Grasslands National Park in Saskatchewan, Canada. This disease, caused by the bacterium Yersinia pestis, circulates in small wild mammals in some regions, and is spread by fleas. While plague is endemic in some parts of North America, it's very rare in Canada. (The last reported human case was in 1939).
Prairie dogs are highly susceptible to plague. The most likely problem with plague occurring in prairie dogs in Grasslands National Park will be the impact on the prairie dog population itself. Outbreaks of plague in prairie dogs can be devastating, virtually wiping out entire colonies.
- Plague can be transmitted to people, but the risk here is quite low. For people to become infected, they have to be bitten by a flea that was infected by biting an infected prairie dog (or other animal). The risk of exposure to a flea infected by wildlife is pretty low if people aren't crawling around prairie dog holes and take some basic precautions.
- The risk to pets is similarly low. Cats are more susceptible to plague than dogs, but they have to be exposed via a flea or, more commonly, from hunting and eating infected wildlife. There presumably aren't too many pet cats in Grasslands National Park, so the risk of exposure is probably limited. Dogs are rather resistant to plague, but they are probably at increased risk of exposure in a situation like this because they are more likely to be taken into areas where infected animals and fleas may be present (e.g. with people going hiking).
The greatest public health and domestic pet concern would be if plague spread beyond prairie dogs and into other small mammal populations that live closer to people or that have more contact with pets. The likelihood of this becoming a major problem is pretty low, but it's a serious disease and this situation certainly needs to be monitored.
In response to this case, park personnel are monitoring prairie dog colonies to look for more cases. They are presumably also keeping a close eye out for any other unexpected deaths of small mammals. Park officials have recommended that people stay away from prairie dog colonies, tuck their pants into their socks (to keep out fleas) and use insect repellent on their shoes. They have also closed some areas to domestic pets.
Photo: Black-tailed Prairie Dogs atop their burrows in Grasslands National Park in Saskatchewan, Canada (source: www.canada-photos.com)
