The title says it all. Here are the most recent maps from WormsAndGermsMap showing equine cases of West Nile virus and Eastern Equine Encephalitis (EEE) virus infection. As with any surveillance, the maps only capture a percentage of the true number of cases, but looking at the geographic distribution and trends in date-of-onset can still be informative.
The latest edition of the Journal of Feline Medicine and Surgery contains an American Association of Feline Practitioners (AAFP) position statement entitled “Impact of lifestyle choice on the companion cat: indoor vs outdoor”. (The document is actually an update of the previous 2007 position statement “Confinement of Owned Indoor Cats“.) It’s an interesting position statement that tries to balance a lot of issues. There are various arguments both ways, involving health, welfare and behavior. Some people vehemently oppose cats being outdoors because of the number of birds and rodents that they kill, or because they can be injured or killed by vehicles and predators. Some think they’re born to roam. However, let’s just focus on the infectious diseases and zoonotic diseases aspects here.
This one’s easy. There are lots of potentially zoonotic bacteria and parasites that cats can acquire outside, from hunting birds and rodents, picking up fleas and encountering other animals. These include things like Salmonella, Toxoplasma and Bartonella. Indoor cats are at much lower risk of shedding many of these zoonotic pathogens. They are also less likely to be injured, reducing the chance of wound infections that might be zoonotic.
Keeping cats indoors is one of my standard recommendations when there are high risk people (e.g. people with compromised immune systems) in the house.
Feline Infectious Diseases
This one’s pretty clear too. It’s logical. The fewer individuals a cat (or anyone else) encounters, the lower the disease transmission risk. Cats that get outside have a greater risk of exposure to diseases from other cats (e.g. feline immunodeficiency virus (FIV)), insects (e.g. plague in some regions) and prey (e.g. Salmonella). Outdoor cats also get into more fights and not uncommonly end up with cat bite infections or abscesses. The risks are heightened in cats with compromised immune systems and some other illnesses, just like they are for people with compromised immune systems.
Ultimately, while it’s clear that keeping cats indoors reduces infectious disease risks both for the cats and their human contacts, there’s no simple answer to the indoor vs outdoor question. Some people are adamant that cats should be indoors only. Some are adamant the other way. Both groups have good arguments, but sometimes forget the individual aspect… the cat itself.
Myself, I have both. We have Finnegan, a purely indoor cat. This summer, we also adopted two cats as part of the Guelph Humane Society’s Barn Cat Adoption Program. Those two wouldn’t do well indoors (and Finnegan would probably start peeing everywhere if we tried). They live outside (although one, Rumple, has become more of a deck and garage cat). Yes, it increases their risk of diseases and attacks from coyotes and other animals. Yes, they’ll kill some birds and other wildlife. But for them, it was outdoor living or euthanasia.
It’s a complex situation and I know I’ll get strongly opinionated comments in response to this topic. In my perfect world, all cats would be indoors, but not all cats fit into my perfect world. So, I think the default should be keeping cats indoors whenever possible, both for their health and the health of their families. That’s particularly important when the people or cats are at increased risk of disease. But, some cats won’t do well inside 24/7 and some allowances can be made for them as well, in the right situations.
The indoor/outdoor decision needs to be made based on a large number of factors and there’s no single approach that works for all cats, households and regions.
The position statement can also be found on the AAFP’s website: http://www.catvets.com/guidelines/position-statements/lifestyle-choice-position-statement
Raccoon-variant rabies cases around the Hamilton area continue to trickle in slowly but steadily each week. The total number of cases is now up to 187 since December 2015, with 132 cases in raccoons and 53 in skunks. The remaining two cases were in less common – but not altogether unexpected – species: a fox and a cat. Both were almost certainly exposed to the virus through contact with a positive raccoon or skunk. Although there is also fox-variant rabies in Ontario (most recently two cases found in the same area of Perth county between December 2015 and March 2016), this fox was from the Hamilton area and the virus was typed as raccoon-variant. It’s very important to remember that all mammals are susceptible to all variants of rabies virus (including bat-variant), the names we give the variants simply reflect the species in which each “strain” circulates most commonly.
The rabid cat was the first rabid cat found in Ontario since 2012. It was a stray cat from the Hamilton area, but it was taken to Haldimand before it got sick, by someone who wanted to adopt it. This is a relatively small-scale example of how well-meaning individuals can inadvertently help diseases move long distances very quickly (the same thing can also happen with rescue dogs from other countries, with both rabies and other diseases). Fortunately the veterinarian who saw the cat was aware that there was rabies in the area, and knew to contact the local public health unit in this case, because there was at least one person who was exposed to the cat’s saliva. Once the test result was known, OMAFRA also assisted the local veterinarians with recommendations for management of any pets that had potentially been exposed to the cat. The public health unit has ensured that any exposed people are provided with post-exposure prophylaxis (PEP). Stray, ferral and community cats are often unvaccinated and are at increased risk of exposure to wildlife (some of which they may even compete with for food sources), and they can pose an increased risk of rabies transmission to people because of increase contact with humans who feed them or otherwise encounter them.
The City of Hamilton, with the help of ten local veterinarians and many other volunteers, has organized a large public rabies vaccination clinic for tomorrow (September 17). They are hoping to vaccinate 500 cats and dogs. Owners can bring their pets to Gage Park from 9AM-3PM and have them vaccinated for rabies for $25 each.
The Ministry of Natural Resources and Forestry continues to test wildlife from the surveillance zone that are either found dead or euthanized due to illness or unusual behaviour. They have also produced two new posters for the public about Protecting yourself and your pets and Rabies vaccine for wild animals (the later is specifically for people living in the zones where the MNRF is distributing oral rabies vaccine (ORV) baits for wildlife). Printed copies of these posters are also available through the MNRF.
Rabid bats also continue to be found periodically throughout Ontario, which is not unusual as it is well known that rabies is endemic in the bat population at a very low level. That’s why it’s always important to avoid contact with bats (and to vaccinate even indoor cats – because bats can and do get inside periodically!).
The latest terrestrial case maps and maps of the baiting zones can be found on the OMAFRA rabies website (along with lots of detailed information for Ontario veterinarians), as well as the Ontario.ca rabies website on the “rabies in wildlife” page.
I spend a lot of time talking about “emerging” infectious diseases. Some of these are truly emerging (i.e. new) diseases, some are conditions we couldn’t diagnose well before but now recognize more easily, and some are disease that have been there all along and are just getting more attention. However, while emerging infectious disease (especially zoonotic diseases) attract attention, we can’t ignore the “run-of-the-mill” problems.
Case in point: animal bites.
Bites are the most common animal-associated illness, and often lead to infection from bacteria in the animal’s mouth or on the person’s skin. A large percentage of bites are preventable, with education, training and supervision.
While we don’t want to blame the victim, there needs to be an onus on people to help protect themselves. I’m not always a fan of infographics and posters (since I’m not sure most really achieve anything) but here’s a bite-prevention poster from Spokane County (Washington State, US) that I really like.
Hot off the presses in the Journal of the American Veterinary Medical Association (JAVMA) is a guidance document aimed at reducing infectious disease risks in a variety of canine group settings. The paper, Risk reduction and management strategies to prevent transmission of infectious disease among dogs at dog shows, sporting events, and other canine group settings (Stull et al, J Am Vet Med Assoc 2016) discusses a variety of issues, risks and recommendations. While we can never eliminate infectious disease risks, a lot of practical measures can be taken to lessen the risk, while still allowing for normal operation of a show, meet, kennel or similar event. The document can be downloaded by clicking the title above or directly through the JAVMA website.
Arboviruses (ARthropod-BOrne viruses) are viruses that are spread by insects, often mosquitoes. As I’ve written about recently, mosquito biology and differences in reservoir species mean that mosquito-borne viruses can have quite different patterns of distribution and spread. As is common, the occurrence of West Nile virus infection in horses tends to ramp up in late August and into the fall, and is broadly spread across North America. In contrast, Eastern Equine Encephalitis virus (EEE), while a cause of nastier disease, tends to have a more narrow geographic range, occurring mostly along the Atlantic and Gulf Coast regions in the US. West Nile cases in particular seem to be spiking lately. Check out Worms & Germs Map (www.wormsandgermsmap.com) for the latest case maps. As always, these maps don’t show every case of disease, just those that are diagnosed and reported through various means, but they do provide an interesting snapshot of these two diseases.
Eastern Equine Encephalitis in horses, last update Aug 30, 2016
West Nile virus in horses. Last updated Aug 30, 2016.
A vague but potentially interesting report from New Jersey outlines a request for information about pet deaths in the area.
The Cumberland County [New Jersey] Health Department is asking for the public’s help in collecting data on reports of what it calls “sudden and unusual illness” among dogs in the county.
- Perhaps the most interesting and important part is that the Health Department is leading the charge. Too often, there’s little interest from the human-health types in situations like these.
Officials say sometimes these illnesses are chronic and sometimes they can come on suddenly. The county health department, in collaboration with the New Jersey Department of Health Zoonotic Disease Unit, announced on Friday that it is collecting information from those dog owners that feel their pet’s recent illness falls into this category. Although most of the concerns have been regarding dogs, the county officials said in a news release, they would not exclude information regarding severe and unusual illnesses in cats. Health officials say they encourage pet owners to consult with their veterinarian if they see signs of their dog or cat falling suddenly ill. Signs of illnesses in dogs can included lethargy, vomiting, diarrhea, refusal to eat and muscle weakness.
According to a health department spokesman, “a handful of dogs” have been reported ill, mostly in the Millville area.
In the past week three of those have died. Among them was one dog which was older and displayed symptoms of pneumonia.
The health department is asking for the public’s health in gathering information as a proactive measure to determine whether, in fact, there is a widespread problem.
While the department is currently focusing on the collection of information regarding recent illnesses in dogs, we encourage residents to always reach out to a veterinarian regarding any unusual and sudden illnesses any type of pet exhibits.
Reports like this come out in the press occasionally. These can be:
- True new problems
- Outbreaks caused by existing and well know pathogens
- Misinformation or over-reaction
All of these happen, but #3 is probably the most common, followed by #2. I often get involved in investigating reports like these, and it’s usually frustrating (and fruitless) because of a lack of clear information. So, from that standpoint, getting the word around to as many people as possible is very useful.
The information that’s provided is pretty vague in this case, probably because they have little information to go on. Unfortunately, this can ramp up unneeded concern because pretty much any sick dog or cat could fit this description.
While the information is vague and the response isn’t clear, this type of approach can be useful if owners are paying attention and officials are collecting good information. Early response is key to controlling infectious diseases, and it’s much better to over-react occasionally than to wait until there’s definitely a problem, at which point control may be much more difficult.
Key actions for a situation like this are:
- Raising awareness: this report is a good start.
- Collecting information about sick animals (what’s wrong, where they have been, what testing has been done): this requires some work but it sounds like they’ll be tracking at least some of this.
- Collecting samples for testing to identify a cause: this is where things sometimes fall off the rails. Diagnostic testing can be expensive and often we don’t have many test results to evaluate. That’s particularly true when testing may not influence care of the animal. Most people aren’t into paying for testing for the “greater good” if it won’t help their pet.
- Engaging experts in veterinary infectious diseases and infection control: this is important to help determine potential causes, identify potential control measures and figure out how to arrive at a diagnosis (and maybe identify a new cause).
Agritourism is becoming a big industry. As our society gets more urbanized, there’s increasing interest in visiting farms and similar environments. Things like farm visits and petting zoos can be great, especially for kids. They’re also sometimes associated with infectious diseases, most often in kids.
Some agritourism events are well run and take a lot of measures to reduce the risk of disease transmission (and injury). Some… well… they aren’t living up to the increasing standards and expectations.
A few years ago, we did some studies looking at petting zoos and infection control practices. Various issues such as having high risk species (e.g. calves, young poultry), people eating in animal contact areas, limited handwashing facilities and lack of supervision were common (Weese et al. Clin Infect Dis 2007). A webcam- based observational study at one event showed that even with good design, handwashing rates amongst participants were relatively low (Anderson and Weese, Epidemiol Infect 2011).
I think things have improved a bit around here over the last few years, but it’s still not hard to find some pretty dodgy events. Further, it’s not hard to find reports of infectious diseases or outbreaks associated with events like these (for example, recent cases of E. coli infection associated with a county fair in Oregon). While these events can be rewarding, more needs to be done to reduce the risks associated with them.
An agritourism operator isn’t necessarily an infectious disease expert. As a result, information about how to reduce infectious disease risks is needed. Sometimes there’s just a basic “wash your hands” poster from the local public health unit. That’s a start, but is only part of the story. More comprehensive guidelines are becoming available to help facilities better design and operate their events, thus protecting the public and themselves (lawsuits are far from rare when it comes to farm-associated diseases, especially outbreaks).
The Upper Midwest Agricultural Safety and Health Center (UMASH) has launched a new website with some good information for agritourism operators and the general public. These types of resources should be mandatory reading for anyone operating an agritourism event.
Dogs’ noses are used for a lot of things. Some are conventional (e.g. tracking, search and rescue, drug detection), some are a bit outside of the box (e.g. detection of Clostridium difficile, identifying floating whale poop). A recent paper in Open Forum Infectious Diseases (Maurer et al 2016) takes this to another level by investigating the use of dogs to detect bacteriuria – the presence of bacteria in a urine sample.
Five dogs (Labs and Golden retrievers) were trained to detect contaminated urine in scent detection boxes. When they came across a contaminated urine sample, they sat in front of the box. That’s a pretty standard training approach.
After the training phase, they took urine samples with fairly high levels of bacterial contamination and samples with no bacteria, and saw how good the dogs were at identifying the contaminated samples. They then tested urine samples that were diluted to 1% and 0.1% and did the same thing.
The results were pretty impressive:
- For E. coli, the most common bug involved in urinary tract infections, the sensitivity of the “sniff test” was 99.6%. That means the dogs detected 99.6% of positive samples (and therefore had few false negatives, aka samples that were actually positive that they missed.) The specificity was 91.5%, so 8.5% of positives were false positives (aka negative samples that were mistakenly identified as positive). Overall, the results mean that if bacteria were present, the odds were very good that the dogs would detect it, with a relatively small percentage of additional positives being false alarms.
- Results were similar with other bacteria.
- Diluting samples to 1% or even 0.1% did not impact the sensitivity or specificity.
So, it seems that dogs can do a good job figuring out whether urine has bacteria in it.
Is having a dog that is able to detect bacteria in urine samples useful?
- Probably not, at least in practical terms. I doubt someone’s going to keep a trained dog around to pre-screen urine samples.
- Testing urine for bacteria only provides part of the needed information. The susceptibility of the bacterium to antibiotics is another key piece of information, something that even the best dog nose can’t sort out.
What if the dogs can detect bacteriuria directly in certain people, such as those with spinal cord injuries or other conditions that hide other signs of urinary tract infections?
- That might be more interesting. However, asymptomatic bacteriuria (presence of bacteria in the absence of disease) is common in these same groups of patients and treatment is rarely needed, so it might not be a useful screening tool anyway. In fact, there’s a lot of effort being taken to reduce unnecessary cultures and unnecessary treatment of people with asymptomatic bacteriuria, so finding more of those individuals might be counterproductive.
How well would dogs do trying to detect bacteriuria directly in people?
- That’s another good question. I suspect there’d be a lot of other distracting smells when sniffing urine directly from a person or other animal.
- However, an interesting anecdote is reported in the paper. One month after the study, one of the dogs alerted to a person at the training centre. That person wasn’t feeling well but didn’t suspect a urinary tract infection. However, based on the dog’s response, a urine culture was done and bacteria were present.
Regardless, it’s an interesting study and certainly not the last report of using dogs to detect a human health problem that we’ll see in the near future.
It also makes me wonder about owning or handling one of these dogs. It might be a bit awkward explaining to the person you meet walking down the street why your dog is sitting in front of them and staring at them. A little too much information perhaps.
In terms of my own dog, Merlin, well, he has a great nose and he’s great at the “staring at someone’s crotch” component that a dog like this would need. Unfortunately, the connection to his brain (what there is of that) is pretty weak. He’ll remain blissfully unemployed.
There are a lot of gross parasitic diseases. A prime example is dracunculiasis, otherwise known as Guinea worm (Dracunculus medinensis) infection. People get infected by drinking water or eating undercooked fish contaminated with “water fleas” that are infected with Guinea worm larvae. Over a year or so, the worm grows silently in the body, with females reaching 60-100 cm in length. Fertilized female worms work their way to the skin surface, usually in the lower leg, cause a small blister. There, they expel larvae into water, where they can then infect someone else. The adult worms continue to emerge over the course of a few weeks, a very painful and troubling process for the infected person (see life cycle diagram below).
The image (left) depicts the emergence of a female Guinea worm from the lower leg of a person. Once the worm emerges from the wound, it can only be pulled out a few centimeters each day and wrapped around a small stick, or piece of gauze. Sometimes the worm can be pulled out completely within a few days, but the process often takes weeks. (Image source: CDC Public Health Image Library #8211)
Significant efforts have been underway to eradicate Guinea worm, and they’ve made a lot of progress. Human cases had dropped dramatically, from millions to handfuls. In 2014, only 126 cases were identified (down from 3.5 million in 1986); cases were from Chad, Ethiopia, Mali and South Sudan. Guinea worm was thought to have one key property necessary for successful eradication of disease: a single definitive host species. It was believed that the parasite needed humans to complete its life cycle, so if the disease could be eradicated in people, the parasite would be eradicated completely.
Unfortunately, that doesn’t appear to be the case. Guinea worm is now being found in dogs. Guinea worm infections in dogs were first identified in Chad a couple years ago (Eberhard et al, Am J Trop Med Hyg 2014), and the numbers seem to be increasing. 600 infected dogs have been identified in Chad so far this year, so canine cases have now surpassed human cases, and it’s logical to assume that this represents just a small fraction of the true number of infected dogs. This complicates matters greatly, since it’s now evident that eradicating Guinea worm not only requires elimination of the parasite in people, but also in dogs (and possibly other species). That’s challenging, since keeping infected dogs tied up and away from water sources (which they can contaminate with the parasite larvae) for a couple weeks as the worm makes its way out of the body isn’t easy to do. The Carter Foundation is actually paying people to do just that, which actually seems to be helping.
Whether dogs are a source of Guinea worm outside of Chad, and how much they contribute to human infection needs to be studied. Methods to prevent and treat infections in dogs need to be investigated too. At best, this will complicate and delay eradication of Guinea worm. At worst, it will prevent eradication altogether. Efforts to reduce exposure of people through access to uncontaminated drinking water will still be effective, but the more infected individuals (canine or human), the more surface water contamination there is. Exposure to people via surface water is hard to completely eliminate, so if it remains in dogs, human infections will continue to occur.
This is just one more example of how parasites (like bacteria and viruses) often find ways to confound our thinking.