Worms and Germs Blog

Flesh eating disease from a cat bite

Scott Weese — Mon, 14 May 2012 19:51:00 -0500

An Albany, Georgia woman is fortunately recovering from necrotizing fasciitis (flesh eating disease) that developed after a cat bite. The cat presumably wasn't the source of the bacterium that caused the disease, but it was the source of the wound that let the bacterium (usually Group A Streptococcus sp) get into her body in the first place, and from there the infection spread rapidly.

In this case, the woman was bitten on the hand by her cat. There's no mention of what she did after the bite, but often people don't take adequate precautions after cat bites because they can appear minor. While the trauma can be minor, cat bites are notorious for causing infections because they can drive bacteria deep into tissues, making it easy for infections to develop.

Four days after the cat bite, the woman's hand "blew up" and she was rushed into surgery. It's an emergency situation because death rates can be high, and those people lucky enough to survive can still have serious complications sometimes requiring measures as drastic as limb amputation, and the extensive tissue damage can lead to chronic problems for the rest of their lives.

People shouldn't worry about getting flesh eating disease from their cat (in part because people don't actually get this kind of infection from cats, it's just that bites can predisposed them to this (and other) kind of infection). However, people should be aware of potential issues associated with bites (from cats in particular, but also from any kind of animal). This case is just one more warning about a range of potential problems that can develop following a cat bite. Any cat bite should be taken seriously and at a minimum promptly and thoroughly cleaned. Bites that occur over the hands, feet, face, joints and similar high risk sites or that occur in people with compromised immune systems should be evaluated by a physician - and sooner rather than later. It's much easier and better to prevent an infection from developing than to try to control an established infection, and while most cat bite infections are mild, serious problems are far from rare.

More information about cat bites can be found on the Worms & Germs Resources - Pets page.

Horse flu concerns at French show

Scott Weese — Mon, 14 May 2012 15:19:00 -0500

Two horses have been removed from the showgrounds after testing positive for equine influenza virus at the FEI show jumping event in La Baule, France. The horses were not showing any signs of illness but were positive on PCR testing (presumably from a nasal or nasopharyngeal swab) and were sent home, along with four other horses taken care of by grooms of the two test-positive horses. Organizers are also planning to isolate all the horses that were in the same stable block as the positive horses, but they will stay on the showgrounds.

Authorities were monitoring horses at this show after a confirmed case of equine influenza was identified at a horse in another recent horse show in France. The article states that "precautionary testing on some horse was undertaken" but it's unclear how horses were selected for testing. Was it random? Were horses that had been to the other show tested? Had the horses tested been in contact with those other infected horses?

Testing of all horses is an aggressive (and expensive) approach, but equine influenza is an ever-present risk at shows and it's highly transmissible, so it may have been decided that the time and effort was worth it to test at least some of the animals.

The two positive horses were healthy and may not develop influenza. The test that was used is highly sensitive and detects viral RNA. That means if the test is positive there is actually flu virus present in the horse, as opposed to blood tests that detect antibodies to the virus, which simply determine whether the horse has been exposed. Viral PCR tests can also pick up dead virus, but it's unlikely that a horse would have RNA from dead influenza in its nose in the absence of an infection.

Since these horses are currently healthy, there are a few possible explanations:

They are incubating flu and will get sick soon. Horses can start shedding the virus before they get sick, which complicates influenza control.
They could have had flu and recovered. However, since horses only shed the virus for a short time and it would be very unlikely for the horses to have been sick and recovered, and still be shedding the virus.
The horses might be infected but developed a very mild or clinically unapparent infection. They might have had enough inherent or vaccine-induced immunity to prevent disease from occurring but not enough to prevent the virus from growing. Flu vaccines are designed to reduce the incidence and severity of disease, not viral shedding,
It could have been a false positive lab test.

Is testing and exclusion of healthy test-positive horses overkill?

No, I don't think so. It's certainly aggressive, but it is a reasonable approach to dealing with a concerning and highly transmissible infectious disease, although even so it won't eliminate all infectious disease concerns. People whose horses are excluded probably don't like it, but hopefully they see the greater good, meaning "what goes around comes around" (or more specifically when dealing with disease control "what doesn't go around doesn't come around," and hopefully their horses will have a lower chance of being infected in the future because of similar measures taken by other people).

Diamond Pet Food recall questions

Scott Weese — Fri, 11 May 2012 13:03:00 -0500

I'm getting a lot of questions now about canine aspects of this recall, so I've addressed my take on some of the important issues below.

Can Salmonella cause disease in dogs?

Absolutely. The common myth about dogs being immune to Salmonella (mainly found on raw food sites) is just that: a myth. Dogs can and do get Salmonella infections, and it can make them sick.

Are dogs getting sick because of the recalled food?

I don't know but I suspect they are. There's no reason to think that the strain of Salmonella involved here would infect people but not dogs. The reason that there are reports of human but not canine cases could simply be because there is a formal surveillance and reporting system for humans but not dogs. Also, testing is not commonly performed on dogs with diarrhea, so large numbers of cases could go unidentified.

What would a sick dog look like?

The most common presentation of salmonellosis in dogs is diarrhea. Vomiting, lethargy and lack of appetite may also be present. Diarrhea can range from mild to severe and bloody. Chronic diarrhea can also develop but is less common. Other types of infections such as bloodstream infections can occur, with or without diarrhea, but these are pretty rare.

How do I know if my dog has salmonellosis?

The only was to know is to try to detect the Salmonella bacterium. This usually involves testing of stool samples. Culture is the standard and preferred approach, and is best done by a lab experienced with Salmonella testing and one where selective culture methods will be used. PCR, a type of molecular test, can also be used to detect Salmonella DNA. The quality of these tests (and the labs that offer them) is quite variable, but some of these tests are quite good. The downside is that all you find out with PCR testing is whether Salmonella is present or not. With culture, the bacterium can be tested further to see if it is the outbreak strain, and it can be tested for its susceptibility to antibiotics in the uncommon event that antibiotic treatment is needed.

My dog is healthy but has been fed recalled food. Should he/she be tested?

I don't recommend that. I only want to do a diagnostic test if I have a clear plan regarding how to use the results, which wouldn't be the case is a situation like this. If the dog was positive for Salmonella, I wouldn't do anything special except remind you to avoid contact with its poop (which you should be doing anyway). We don't treat Salmonella carriers - dogs that are healthy and shedding Salmonella will eliminate it on their own, usually within a couple weeks. A negative result also doesn't guarantee that the dog is truly negative. Usually we want multiple negative cultures to rule out Salmonella since it can be shed intermittently and can be hard to detect.

My dog is healthy but has been fed recalled food. Should he/she be treated with antibiotics?

NO. That's the last thing I want to do. Antibiotics are not very effective (or effective at all) at eliminating Salmonella that's living in the intestinal tract. A healthy animal shedding Salmonella is an indication that the body is handling it. It doesn't mean that disease won't occur, but one critical aspect for preventing intestinal infections is the protective effect of the gut microbiota - the trillions of bacteria that are in the gut helping suppress "bad" bugs like Salmonella. My concern with prophylactic treatment is that we might make things worse by suppressing this protective bacterial population and letting Salmonella overgrow in a situation where it otherwise would not have been an issue.

Latest round of rabies news

Scott Weese — Wed, 09 May 2012 15:30:00 -0500

ProMed's latest accumulation of rabies reports has the typical mix of domestic animal and wildlife rabies cases, and some recurring themes.

Fox / dog / human, North Carolina

In this case, a rabid fox had a "direct encounter" with several people, then it was killed by a dog. Three people have started post-exposure treatment.

The article states that the dog was vaccinated against rabies, which is good to hear. However, it goes on to say that exposed pets need to be euthanized or have a 6 month quarantine. In reality, standard guidelines are that unvaccinated pets are treated like this while vaccinated pets undergo a less rigourous 45 day observation at home. Hopefully the discrepancy is simply due to inaccurate reporting and not misinterpretation of guidelines by local officials.

Cat / human, Maryland

A rabid stray cat scratched five people, who have been urged to undergo post-exposure treatment. Officials are calling for anyone who potentially had contact with this cat go to an emergency room.

However, odds are if someone goes to an emergency room and says they might have had contact with this cat, they're just going to sit around until someone tells them they don't know what needs to be done, or to go home and deal with someone else. Rabies exposure is a medical urgency, not an emergency. People should take a little extra time to work with their physician and/or public health rather than go to the emergency room.
People who may have had contact with the cat need a proper assessment to determine if they were potentially exposed to rabies, since just being around the cat or having casual contact is not a risk. Scratches are a bit controversial since they are low risk for rabies transmission (unless the scratches become contaminated with saliva from the animal), and there are conflicting guidelines regarding what to do for a person who is scratched.
This is also a good reminder to stay away from stray cats.

Fox / human, Pennsylvania

In this report, authorities are trying to find a person that cradled an injured fox in a blanket. The fox was subsequently identified as rabid and they need to determine whether the person was potentially exposed to the virus.

Again, another reminder to stay away from wildlife, and if there is contact with wildlife, make sure rabies exposure is considered.

Bat / human, Indiana

A student was bitten by a rabid bat while he slept in an Indiana University dorm room. He woke up after being bitten (good thing, since he probably wouldn't have noticed otherwise due to the often tiny marks left by a bat bite). He is now receiving post-exposure treatment.

Rabies isn't going away, at least any time soon. People need to be aware of the risks in rabies-endemic areas, take care around wildlife and vaccinate their pets.

Photo credit: Rob Lee (click for source)

Vesicular stomatitis and Canadian horse import restrictions

Scott Weese — Sat, 05 May 2012 07:00:00 -0500

The Canadian Food Inspection Agency has implemented import restrictions in response to diagnosis of vesicular stomatitis (VS) in a horse in Otero County, New Mexico.

Why the fuss?

VS is a viral infection that can affect a range of animals species. In addition to horses, it can infect cattle, pigs and sheep (and a few others). It produces painful blisters in the mouth and other areas that can result in decreased eating and drinking, lameness, severe weight loss and secondary infections. In food animals, it can cause severe economic losses. Another issue is that in cattle and sheep, it looks like the dreaded food and mouth disease. Lab tests can distinguish the two, but there can be a lot of angst when sorting out what causes vesicular diseases in cattle.

VS is a reportable disease in Canada and was last identified in the country in 1949. Import restrictions are a routine measure in response to the periodic US cases that occur.

In this case, the following restrictions have been implemented:

Horses cannot be imported from New Mexico.
Canadian horses that are in New Mexico must either get an import permit and supplemental USDA health certificate, or must be moved to another state for at least 21 days prior to returning to Canada. The supplemental certification indicates they've been evaluated by a veterinarian, have not been on a farm where VS was present over the past 60 days, and have a negative VS blood test. Horses that are moved to another state require a USDA certificate indicating that they've lived in that state for at least 21 days. (This may be complicated by restrictions implemented by other states on accepting horses from New Mexico.)
All other horses coming from the US must be certified by the USDA as not having been in New Mexico in the past 21 days.

Image: Ulcers on the tongue of a horse infected by vesicular stomatitis (VS) virus. Image source: Colorado State University Extension

Diamond Pet Foods Salmonella outbreak

Scott Weese — Sat, 05 May 2012 06:32:00 -0500

After starting off like a simple recall of potentially Salmonella-contaminated dry pet food, the Diamond Pet Food problem has now expanded into a multistate outbreak of salmonellosis in humans linked to exposure to the contaminated pet food. At last count, there were 14 affected people from 9 US states, including 5 who required hospitalization. These numbers could increase since so far they only include people who got sick up to April 1 (because it takes time for Salmonella to be grown in the lab, sent to CDC for testing and the result investigated, later cases may not have been reported yet).

This outbreak involves Salmonella Infantis, a strain that is uncommonly identified in people. Finding an increased number of infections caused by an unusual strain makes it easier to identify an outbreak, as was presumably the case here. This strain has also been isolated from various types of pet food that were produced at the Diamond Pet Foods' South Carolina plant. Despite the name, this strain of Salmonella is not more likely to infect infants, and people ranging from less than 1 year to 82 years of age have been infected.

Details about the types of contact people had with the pet food are limited. 70% of infected people reported having contact with a dog the week before getting sick. How the other 30% could have been exposed is unclear. Sometimes peoples' recall is poor, especially if they had transient contact with a pet. Individuals could have been exposed from environmental contamination when visiting a household where contaminated pet food was fed, without having direct contact with a pet. It's also possible some cases are not directly related to the outbreak and co-incidentally were exposed to the same strain from some other source.

Since we see periodic outbreaks associated with dry pet food, does that mean that other types of pet food are safer? Not really. Canned food is ultimately the safest because of the heat processing, but it's not practical for all animals.

Typically, after a report like this, I get a barrage of emails from people saying "See... we don't have large outbreaks from raw food diets so they are safer." Unfortunately, that's not the case. High pressure pasteurization (HPP) of raw food, a process that uses pressure with minimal heat to kill bacteria, is an effective method for reducing contamination of such products with harmful pathogens like Salmonella, and HPP is now being used by a couple of companies. These raw diets should be quite safe from a Salmonella standpoint. Otherwise, the risk of Salmonella contamination of raw pet foods is still very high, and if anything, the dry food outbreaks show how people can be infected from contaminated pet food.

Why don't we see large outbreaks associated with raw food? Outbreaks get detected because certain patterns or unusual findings are identified. Raw pet food associated outbreaks probably occur but are not as readily identifiable since raw meat contamination is common but involves variable Salmonella types that regularly change. In a situation like that, you can potentially have lots of people getting Salmonella from raw food, but if there is limited commonality in strains and products, it doesn't get picked up as an outbreak. That's particularly true when the strains that are involved are the common ones found in food, since they would often be dismissed on the premise that the person likely got it from some unknown food source. Without large numbers of cases in an area or a cluster of unusual strains, the investigation wouldn't likely get very far and nothing would be reported.

How do reduce the risk of getting Salmonella from pet food (or your pet)?

Don't feed pets in the kitchen. This practice has been associated with an increased risk of disease in a previous outbreak of salmonellosis in children.
Wash your hands after handling pet food.
Don't let young children have contact with pet food.
Use common sense when handling pet feces.

More information about both Salmonella and issues pertaining to raw diets (including how to reduce the risk) can be found on the Worms & Germs Resources - Pets page.

Botulism outbreak kills 23 horses

Scott Weese — Tue, 01 May 2012 07:28:00 -0500

Botulism has been in the news lately, with numerous outbreaks involving different species and some human food recalls. Botulism outbreaks are often pretty dramatic because of the number of individuals that can be involved, the severity of disease and the fact that it's often difficult to do much beyond damage control once the problem is recognized. Recently, there have been reports of widespread duck deaths along with a couple of different recalls and warnings in Ontario about potentially contaminated smoked salmon and improperly eviscerated salted fish.

On the equine front, there's also been a large botulism outbreak that is believed to have killed 23 horses in Maine (USA). The outbreak occurred over the last month and, as is typical, has been devastating because of the profound susceptibility of horses to botulinum toxin and the inability to do much to save the animals once it was realized that botulism was present.

In adult horses, botulism is caused by ingestion of food that's been contaminated with toxins produced by the bacterium Clostridium botulinum, as it grows. This relatively widespread bacterium doesn't normally grow and produce toxins in horse feed since it requires an oxygen-free environment and other specific conditions, but when these occur, the incredibly potent neurotoxin can be produced. Equine outbreaks are often associated with haylage or silage (which if improperly fermented allow for C. bolulinum to grow) or contamination of round bales (e.g. an smaller animal that died of botulism gets accidentally incorporated into the bale, where the toxins can persist and/or the bacterium can grow if the right environment is present deep within the bale). In this outbreak, silage is suspected to be the cause. The silage is being tested to confirm this suspicion.

You can never 100% prevent botulism, since strange sources are sometimes found, but avoiding high risk feeds (e.g. silage, haylage, moldy round bales), trying to ensure that dead animals do not get caught up in hay bales during the baling process and taking exceptional care when baling if botulism is present in wildlife in the area can help greatly. A vaccine is available but it only protects against certain types of botulism. If those types are the main types that cause disease in a given area, vaccination can be useful, but good feeding practices are the most important preventive measure.

Image: Horses at a round bale feeder (source: www.omafra.gov.on.ca)

Dog importation issues

Scott Weese — Thu, 26 Apr 2012 19:17:00 -0500

Recently, I've had a run of interesting advice calls about strange infectious diseases in dogs that have been imported from various countries. At a meeting the other day, I had some discussions with colleagues from across Canada who have also seen various infectious diseases in imported dogs.

Imported infectious diseases are a concern for a few reasons:

Some could spread to other dogs in Canada.
Some could infect insect vectors and eventually establish themselves in Canada.
Some could pose a significant risk to people (e.g. rabies).
Diagnosis of foreign diseases in pets can be difficult because Canadian vets may have little knowledge about them, and they just don't come to mind when evaluating a sick animal.

Some of these sick imported pets are animals adopted by people when traveling. Some arrive via organized rescue programs, both from the US and beyond (we'll leave the discussion about the ethics and economics of importing stray dogs from different regions when we have no shortage of them here for later).

One thing that strikes me as bizarre is how easy it is to import a dog from any country. I do a fair bit of international research and regularly import samples like nasal swabs and fecal samples from different countries, and it's more effort for me to get a nasal swab into the country than it would be to bring in the whole dog.

For example, if I want to get nasal swabs from dogs from a different country to test them for staphylococci, I need to:

Submit an import permit request to the Canadian Food Inspection Agency (CFIA) (and pay).
Submit a facility certification form to the CFIA signed by our Biosafety Officer.
Submit an import permit request to the Public Health Agency of Canada (PHAC).
Have a facility compliance letter from PHAC that's based on a long questionnaire demonstrating that I have adequate facilities, protocols and training, along with a facility inspection by our Biosafety Officer.

For me to import a dog, I need:

Proof of rabies vaccination

That's it... unless I want to import a dog less than 8 months of age and not accompany it into the country, in which case I also need a health certificate (which in itself is not much of an indication that there's limited risk of infectious diseases).

Does that seem logical?

The outbreak that won't go away

Scott Weese — Fri, 20 Apr 2012 20:43:00 -0500

The CDC is investigating CDC is investigating more cases of salmonellosis associated with feeder rodent contact, caused by the less-than-catchy-named Salmonella I 4,[5],12:i:-. This strain is the same one that was implicated in a large and prolonged outbreak in the US and UK in 2009-2010 which was also associated with frozen feeder rodents (rodents sold frozen as reptile food) from a single US supplier. The current outbreak has affected people in 22 US states from August 2011-February 2012, and involvement of the same strain from the same source certainly leads to suspicion that this is actually an ongoing problem.

In the latest outbreak:

46 people have become sick. As is common, kids have borne the brunt of this outbreak, with the median age of affected persons being 11 years.
37% of affected people were kids five years of age or younger. Since this outbreak involved feeder rodents, clearly people aren’t heeding the guidelines that kids of that age shouldn’t be in households with reptiles.
No two affected people reported buying rodents from the same store. This shows how widespread the problem is and that it must be originating from the place where the rodents are bred and/or distributed, not a focal pet store issue.

Record-keeping at the pet stores complicated figuring out the source. However, two breeders that supplied pet stores received mice from the company that was the source of the 2009-2010 outbreak. This suggests that not only were people exposed from frozen feeder rodents in the earlier outbreak, but that breeding colonies in different areas were infected from that source. This may have allowed wide dissemination of this Salmonella strain into numerous rodent breeding colonies, creating many possible sources of exposure for members of the public purchasing feeder rodents. The large-scale commercial nature of rodent breeding and wide distribution network creates a great opportunity for widespread outbreaks, as is apparent here and with various other outbreaks (including salmonellosis outbreaks from guinea pigs and baby poultry).

If you are going to buy feeder rodents:

Treat them as if they are carrying Salmonella, because they just might be.
Keep them away from human food. Keep them in a separate freezer or fridge, or in a sealed container if they have to be in the same fridge as human food.
Don't handle them in the kitchen.
Wash your hands thoroughly after handling.
Keep them away from young children, as well as people with compromised immune systems, elderly individuals and pregnant women. None of these groups should have contact with reptiles either.

Image: A package of frozen rats, as sold commercially for feeding reptiles.

Toronto rabies case update

Scott Weese — Fri, 20 Apr 2012 20:12:00 -0500

Identification of the strain of rabies in the first person in Toronto to be diagnosed with rabies in the past 81 years has essentially confirmed that the infection was acquired abroad. Toronto Public Health has indicated that the strain obtained from the infected man is one known to circulate in dogs in the Dominican Republic, where the man had been working over the past few months.

Little additional information is being released, including whether the patient is alive (and if so, what his condition is). As part of the typical rabies investigation, 15 healthcare workers and an unknown number of family members and friends have been deemed to have been potentially exposed to rabies from the man and have been offered post-exposure treatment. The risk of human-human transmission is exceedingly low, but given the severity of disease, the logical approach is to err well on the side of caution when considering post-exposure treatment.

While rabies strain typing supports a dog bite as the source, that can't be confirmed at this time since the man was too ill to provide any information by the time rabies was being investigated. Sometimes, exposure is determined indirectly based on information from friends and family (e.g. the person mentioning that he was bitten by a dog) and presumably there is an effort to question people who had contact with the man in the Dominican Republic to try to piece this story together.

Flea collar withdrawal in France

Scott Weese — Tue, 17 Apr 2012 11:32:00 -0500

A group of flea (or flea and tick) collars have been removed from the market in France following a risk assessment. The review looked at these widely available, over-the-counter products that contain a variety of different chemicals. The determination was that the risks posed by contact with the collars (particularly to children) were unacceptable compared to the benefits.

As with most risk assessments, cost-benefit is the key. With flea collars, you have something containing a chemical that's easily (and commonly) touched by people, and you also have the potential that young children could put them in their mouths. That's the "cost" aspect. The beneficial side is two-pronged. One consideration is the importance of flea and tick control to human and/or animal health. That's certainly significant, since fleas and ticks can be associated with various problems, including infectious diseases and flea allergies. However, the other consideration is whether there are safer and/or more effective alternatives. The answer to that is yes - there are now much better approaches for flea and tick control than flea collars in terms of effectiveness and safety. The disadvantage is that these alternatives are somewhat more expensive and not available over the counter, but the cost and logistics are far from cumbersome.

So, the withdrawal of the flea collars from the market in France is a very reasonable move, and one that needs to be accompanied by information to pet owners that emphasizes that:

yes, flea and tick control are still important.
there are much more effective options that are safer for the pet and the family.
people should work with their veterinarian to determine the approach that best fits their pet(s) and family.

Rabies in Toronto man

Scott Weese — Tue, 17 Apr 2012 11:01:00 -0500

Toronto Public Health has confirmed the diagnosis of rabies in a person in the city of Toronto, the first such diagnosis since 1931. Details are limited at this point, but there appears to be strong suspicion that this is a travel-associated infection.

The affected person is a 41-year-old man who was working in the Dominican Republic as a bartender. He reportedly started to develop signs of illness last month - it's unusual for someone to be clinical ill due to rabies for so long, as typically once signs occur they progress very rapidly (and almost always end in death). Regardless, after he became sick in the Dominican, he returned home to Toronto, presumably for more medical care. He was taken to hospital by police after arrival since he was behaving erratically at customs. It's reported that he had fairly serious signs before leaving the Dominican Republic, including trouble swallowing and fear of food, water and air. Given that, I'm amazed that he was allowed onto a plane, even with the pretty lax approach that airlines typically take towards sick people boarding planes. While I know circumstances can be difficult and options may have been limited, this isn't really a good way to bring someone home from a foreign country with an unknown disease. Fortunately, rabies isn't spread by casual contact, but you have to consider the potential for more easily transmitted diseases when you go ahead and put someone on a plane with lots of other people. Thankfully his erratic behaviour started on the ground, not in the air, and he didn't have a more transmissible disease.

The man's current condition isn't clear. It appears that the diagnosis was made a few days ago and he's being treated in hospital. However, rabies is almost invariably fatal, especially when disease is advanced by the time it's diagnosed.

People who have had contact with the affected man are being evaluated to determine who requires post-exposure treatment. Further testing will be done on the virus to see what strain it is, to provide more information about the possible origin. Most likely, it was from a dog bite, but that's just a guess on my part.

While little information is available regarding this case, it's a chance to remind people again of a few key rabies prevention points:

Pets should be vaccinated against rabies.
People (especially kids) should be taught basic bite-prevention practices and to avoid strange animals.
Any bite from an animal needs to be investigated to determine whether there might have been rabies exposure.
Rabies is very common in many countries (especially less developed countries), particularly dog rabies. People need to pay extra attention to bite avoidance when traveling.
Rabies is basically 100% preventable if proper post-exposure treatment is provided. The weak link is often people failing to seek medical care after a bite. That's particularly true for many travelers. If you are bitten while traveling, you need to make sure you get adequate care, or get home to get treated properly, and promptly.

Canine flu in Ontario...not really

Scott Weese — Fri, 13 Apr 2012 08:37:00 -0500

It's amazing how one little email comment can make a mess of my week.

Here's the story: I sent an email to a colleague that works for an agency in Ontario. At the bottom of the email, I gave an FYI about an Ontario dog that was found to have antibodies against canine flu, but that wasn't sick. At the time, I didn't realize that my colleague was no longer at the aforementioned agency.

Astoundingly, instead of cancelling my colleague's email account, the agency had left the account active - and the CEO of the agency reads her emails!
In this case, not only does the CEO read the email, she forwards it to other people in the agency.
Not only do the others read it, they create a release that they send out to associates of their agency throughout the province and some other groups... without contacting me to get details, understand the full story or get permission to use the information I provided. Not exactly a good communications strategy.

In an amazingly short period of time, I was contacted by two provincial Ministries about Ontario's canine flu status, since incomplete information was forwarded to them, and veterinary clinics in the province are now asking questions about our "canine flu case" or "canine flu outbreak."

So, to set the record straight (and decrease the number of phone calls I'm getting today):

We found a dog that had antibodies against canine influenza as part of an outbreak investigation. The outbreak was not caused by canine flu.
The dog had the same antibody level on two blood samples taken two weeks apart. This is not consistent with disease caused by flu. Rather, it indicates that the dog has been exposed to the virus.
The fact that the dog has been exposed to the virus is noteworthy. The only other seropositive (i.e. antibody positive) dog that we have seen in Ontario was a greyhound from Florida, and we assumed it was infected in Florida. That was a few years ago, and we haven't seen anything since. Initial information indicates that this dog has not left the province, but I'm working to confirm that before I can be confident that this is evidence that canine flu is present in Ontario.

This is an important topic because if/when canine flu hits a region, it certainly has the potential to cause big outbreaks. The outbreak at a Texas racing facility that I wrote about yesterday is a good example of the bad things that can happen when flu hits a susceptible population. Knowing if the virus is in the area is important for things like vaccination programs and making recommendations for management of respiratory disease cases in veterinary clinics and in the community.

We currently have no evidence of canine flu activity in Ontario, but we are actively looking because we assume that it will make it here sometime, if it's not here now. Identifying it early and communicating that properly are critical control measures for canine flu and other emerging infectious diseases, but there's nothing to worry about at the moment.

Bat on a plane

Scott Weese — Thu, 12 Apr 2012 11:16:00 -0500

Don't tell Samuel L. Jackson (Snakes on a Plane was bad enough), but on August 2011, a bat was found flying through the cabin of a plane shortly after take-off from Wisconsin. Failing to heed the seat belt sign, it flew around the cabin a few times before it was eventually trapped in a bathroom. The aircraft then returned to the Wisconsin airport...vnot sure whether that was because they were worried about the bat or because they didn't have an available bathroom any more.

Unfortunately, when they got back to the airport, no one thought to close the plane door before opening the bathroom door, so the bat flew out of the bathroom, out of the plane, down the jetway, through the airport and was last seen exiting the airport via automatic doors (smart bat). The problem with the bat's escape is there was then no way to determine whether it was rabid, since even bats with a good sense of direction can be shedding the virus. Because of that, it had to be assumed that the bat was rabid and an investigation ensued.

The Wisconsin Department of Health called the CDC for assistance and a standard investigation was undertaken. A key component was to determine who, if anyone, was potentially exposed to rabies, assuming the bat was carrying the virus. Rabies is spread through direct contact of saliva from an infected animal with broken skin or mucous membranes (e.g. mouth, nose). Most often, this occurs via a bite. Being in the same area as a bat doesn't constitute a risk.

A rabies investigation typically involves interviewing people who were in the same area as the bat to see if they had any contact with it. That was done, but it was complicated by "difficulties obtaining an accurate passenger manifest...". (Considering it seems like I have to do everything short of depositing a DNA sample to fly to the US these days, I can't fathom how they couldn't have a list of who was on the plane.)

Anyway, the airline gave the CDC a list of 15 people that they knew were on the plane and 33 who had reservations (but apparently they didn't know for sure whether they were on the plane). Considering 50 passengers were on the plane (not counting the bat), that left a few unknowns, which was compounded by their finding that some people who had reservations confirmed they were not on the plane. They tried various ways to contact people, but ultimately ended up with 5 mystery passengers.

Fortunately, the risk of rabies exposure in this case is low. All 45 of the contacted passengers reported having no direct contact with the bat, and it's very unlikely anyone else did given the description of what happened. Similarly, none of the pilots (hopefully it was easy to figure out who they were) and other flight or ground crew reported any contact.

An environmental assessment was performed to see if there was a bat problem at the facility, and nothing out of the ordinary was found. They made a few recommendations to reduce the chance of this happening again:

Use of netting to cover crevices in the airport where bats might roost.
Extending and retracting jetways before the first flight of the morning (I guess to scare the bat out before a plane is hooked up).
Training employees on bat capture methods.
Testing any bats for rabies.

So, it was more of an interesting story than a true disease concern, but with rabies, you have to be thorough to convince yourself that there's no risk.

It also seems like this bat was much more organized than the airline.

Canine flu outbreak in Texas

Scott Weese — Thu, 12 Apr 2012 08:06:00 -0500

As canine influenza continues it's rather gradual, patchwork movement across North America, an outbreak at a greyhound racetrack southeast of Houston highlights some of the concerns about this virus. Canine influenza has been active in the Houston region for some time, causing sporadic infections as well as outbreaks in pet dogs in the community and in veterinary clinics.

Greyhound tracks are a great place for influenza transmission because they have a lot of dogs in close quarters, and racetrack outbreaks can be large and severe. In this outbreak, approximately 100 dogs have been affected so far, with six deaths. It sounds like there are 600-700 dogs on the track, and given how transmissible the virus is, unless they have very tight infection control practices in place to separate groups of dogs (unlikely), it's reasonable to assume that many more dogs will be infected, or have already been infected but weren't recognized because they had mild disease. The ~6% mortality rate is not surprising, as dogs can die from severe influenza or because of bacterial pneumonia that develops afterwards. Higher death rates are talked about, and were features of the early reports of canine flu in Florida, but this lower rate seems to be more typical.

Local Humane Society personnel are rightly warning pet owners to be on the lookout for canine flu. Public awareness is critical, although I'd argue with some of their advice:

"The only protection is the dog flu vaccine."

Not really. It's part of the infection prevention plan but not the only thing. Vaccination is an effective way to reduce the incidence or severity of disease, but it's not 100%. Vaccination should be considered the last line of defense that comes into play when efforts to avoid the virus have failed. If the dog doesn't get exposed to canine flu, it won't get influenza, regardless of vaccination status. Dog owners need to be aware of high-risk situations and avoid contact with dogs that are or have recently been sick. That being said, in an area where canine flu is active, vaccination is a good idea, since you can never completely guarantee your dog won't be exposed to the virus if it's exposed to other dogs.

"Dog owners were warned if they noticed any flu-like symptoms in their dog to take them to a vet immediately for antibiotics and the vaccine and not to take their dog to the park or doggie daycare."

I agree with the last part. If your dog is sick, keep it away from areas where other dogs mingle while it's sick and for about 10 days after it gets better. So, if that's the case, why take all potentially sick animals into the vet right away? It might just result in exposure of other dogs to the virus. If you have influenza and you're not very sick or at high risk for complications, the recommendation isn't to immediately go to the doctor. It's to rest and stay away from other people. The same applies for dogs.
Calling a veterinarian to see whether the dog should be examined makes sense. This also helps ensure that if the dog does go to the clinic, it can be handled properly. By that, I mean instead of showing up, checking in at the front desk and lingering in the waiting room with other dogs for a while, a dog with suspected flu should be admitted directly into isolation or an exam room. This can be done by calling the front desk on arrival or by checking in without the dog, so that the dog can be taken directly to a contained area to avoid other dogs.
Antibiotics are rarely needed. Antibiotics don't kill influenza virus, so they are indicated only if there is evidence (or very high risk) of secondary bacterial disease, which doesn't happen in most cases. We don't want every coughing dog on antibiotics, since few need them.

Pasteurella infection from a dog...not likely

Scott Weese — Mon, 09 Apr 2012 15:22:00 -0500

A few months ago, I wrote about an article that appeared in the journal Orthopedics. It was a very bad article that blamed a person's infection on "excessive contact" with pets, with no evidence that the pets were involved (and no evidence that dogs have ever been found to carry the bacterium in question).

Here's the Letter to the Editor that was just published.

Dear Editor:

I was surprised to see the article “Pyogenic cervical spondylitis caused by Pasteurella haemolytica attributed to excessive contact with dogs” by Machino et al. ¹ The authors stated that Pasteurella haemolytica (which was renamed Mannheimia haemolytica over a decade ago) is a common inhabitant of the oral cavities of dogs and cats, citing prevalence rates of 71% to 90% in cats and 21% to 60% in dogs. However, they provided no references for these prevalence data, and I am unaware of any studies that have found this bacterium in the oral cavities of dogs, let alone at such high rates. The authors cited 3 articles as supporting zoonotic infections with this organism, yet these 3 articles all involved other Pasteurella species. Pasteurella multocida, a completely different bacterium, is a common oral commensal in dogs and cats and has been reported frequently as a cause of pet-associated infection. The authors may have confused these markedly different organisms. The authors also stated that the recent increase in pet ownership has caused an increase in P haemolytica infections from bite wounds, with no evidence supporting an increase in infections caused by this bacterium or the role of pets in human P haemolytica infections. Although zoonotic infections are problematic and it is important to consider the potential role of household pets in human disease, this article is highly flawed, and retraction should be considered.

J. Scott Weese, DVM, DVSc, DipACVIM
Guelph, Ontario, Canada

The authors either didn't get any of the points I made or didn't care and wrote a rather evasive response.

We thank Dr Weese for his letter. We reported a rare case of Pasteurella haemolytica as the pathogenic bacteria behind pyogenic cervical spondylitis. We searched the literature for reports on spondylitis caused by P haemolytica to the greatest extent possible, but it seems that the present case was the first.

In the present case, a needle aspiration biopsy was performed under diskographic guidance, and P haemolytica was detected on bacterial culture. We believed that this case was caused by P haemolytica. Because the patient owns 2 dogs and frequently kisses them on the mouth, this excessive contact was believed to be the cause of infection. No other causes were evident in this case. Although we cannot declare that it is the cause, no evidence was found that it was not the cause.

Our main point in the article was that osteomyelitis has been reported in the field of orthopedics, and, keeping in mind the fact that pyogenic spondylitis is also caused by rare bacterium, we believe it is important to engage in routine treatment regimens.

Masaaki Machino, MD

Anyway, the point wasn't to make the authors look bad. It was to remind people that we need to consider pets as sources of infection but do so in a logical manner, and simply blaming the pet when there's no evidence doesn't do anyone any good.

Bali rabies update

Scott Weese — Mon, 09 Apr 2012 11:57:00 -0500

As we've discussed previously, rabies has been a big problem in Bali since 2008. Previously rabies-free, this densely populated island has been struggling with a large and persistent canine rabies outbreak that has resulted in numerous deaths and much debate about control measures.

A paper in BMC Infectious Diseases (Susilawathi et al 2012) provides a summary of 104 human cases or rabies that occurred in Bali between November 2008 and November 2010. Some highlights:

Dog bites are very common on the island, with a daily average of nearly 100 bites reported over the study period. Since many bites don't get reported, even this large number is an underestimate.
The average age of affected people was 36 years, with a range of 3-84 years. All 104 died.
Most of the cases (57%) were male. This is common, although whether it is because men are more likely to be bitten (because of greater exposure or greater provocation) or less likely to seek medical care after a bite is not known.
There was a history of a dog bite in 96/104 infected people. It's likely a bite occurred for the others as well, but in those cases the patient was unconscious at the time rabies was suspected and family members did not know of any bites.
The incubation period ranged from 12 day to 2 years. It was less than 1 year in 98% of cases. Very short incubation periods, like the 12 day one reported here, are almost always associated with bites to the head or neck, since it's a shorter distance for the virus to travel up nerves to the brain.
Early signs of disease are often vague. Pain or numbness at the location of the bite (37%), nausea or vomiting (30%), fever (22%), aches (17%), headache (16%) and insomnia (7%) were most common.
81% of people that developed rabies did not undergo any type of treatment. 11% washed the wound themselves. Only 6% went to the hospital on the day of the bite. The people who went to the hospital received a course of rabies vaccines but did not receive rabies immunoglobulin (RIG, which is anti-rabies antibodies). So, while they were treated, they didn't get the full recommended treatment. This is incredibly frustrating since rabies is almost 100% preventable if people get proper medical care. Failure of most of these cases to even seek care is a huge issue, and inadequate treatment of people who sought medical care compounds the problem. Not all of the vaccinated people completed the full vaccine course before developing signs of rabies. These were individuals who had short incubation periods because of bites to the head and neck.

These results are not surprising but demonstrate a few important concepts, including:

the need for education of the general public to seek medical care after a bite.
the need for proper education of healthcare providers so that people who are bitten get proper medical care.
the need for adequate supplies of rabies vaccine and immunoglobulin. It wasn't stated whether people didn't receive RIG because it wasn't offered or (as is common in some regions) it wasn't available.
rabies may not be considered initially when signs first start appearing, as many of these people ended up being treated for various other potential problems before rabies was considered. While rabies is almost always fatal, there have been very few "successfully" treated individuals (meaning they didn't die, but they can still have long-term neurological impairment), but to have any chance at success, treatment needs to be administered as quickly as possible.
control of canine rabies is a key part of controlling human rabies.

Rabies exposure and confusion

Scott Weese — Tue, 03 Apr 2012 20:33:00 -0500

Max, a 12-year-old Chihuahua from Greenfield, New Jersey, was euthanized recently after he was exposed to rabies. While far from unusual, the case highlights the ongoing risk of rabies exposure as well as issues with understanding of rabies guidelines and communication.

Max was attacked by a rabid raccoon - an ever-present risk for animals that go outside (or get outside) in many regions. Animal control was called and the raccoon was caught. It was euthanized and rabies was confirmed, indicating that Max was very likely exposed to the virus.

Here's where things seem to get strange. The paper reports:

"Once exposed to a rabid animal, a six-month quarantine is required for the exposed animal, even those animals that have been inoculated with a rabies vaccine."

Not really. In Canada, standard guidelines are for a 6 month strict quarantine for dogs (and cats) that are not properly vaccinated, but only a 45 day observation period is required for vaccinated animals. I don't know if in this jurisdiction they made up their own different rules, whether someone doesn't know what's supposed to be done or whether it's poor reporting, but it's a concern because it can be a difference between life and death... not necessarily from rabies, but from the quarantine requirements alone. People are often unwilling to undertake a strict 6 month quarantine and choose euthanasia (as was the case here), while the 45 day observation period is much more acceptable.

The attending veterinarian stated "Because of the way it was exposed and because of the positive, I think there was a really good chance this dog was going to get rabies".

It's certainly possible, and nowhere does it say whether Max was properly vaccinated. However, there's a reason we vaccinate. It's a highly effective vaccine and we're trying to prevent disease. Nothing's 100%, but with proper vaccination, the risk of rabies is greatly reduced.

It's also stated that "due to the nature of rabies, until behavioral changes occur, the animal is not infectious".

While this doesn't have anything to do with Max's situation, it's not true. Animals can shed the virus for a short period before they show signs of illness. That's the reason there is supposed to be a 10 day quarantine period after a dog bites someone - to see if the dog develops signs of rabies (which would have major implications for the person who was bitten).

Curiously, the article ends with a reminder to vaccinate pets, which seems kind of strange if their assumptions are that an exposed animal will get sick irrespective of vaccination status and that vaccination will have no impact on what happens to an animal after exposure.

However, despite the miscommunication, the take-home message emphasizing the need for vaccination should be heeded. As well, people making decisions about what to do after rabies exposure should make sure they do so based on the best evidence that's available, namely the Compendium of Animal Rabies Prevention and Control.

Salmonella in baby from pet reptile

Scott Weese — Tue, 03 Apr 2012 20:18:00 -0500

.A five-month-old Britich baby was hospitalized with salmonellosis that was presumably acquired from a family pet. The baby developed severe diarrhea and was rushed to hospital. Fortunately, the child has recovered, something that's far from assured in such cases, since salmonellosis can be life-threatening in infants.

As expected, an investigation followed the diagnosis of salmonellosis. Typically, these investigations focus on food and animal contact, and since this family had a bearded dragon (see picture) and tortoises, the investigation honed in on the reptiles. Reptiles are high risk for Salmonella shedding and are commonly implicated in human infections. Further, the type of Salmonella that infected the infant, S. Pomona, is commonly associated with reptiles. It doesn't sound like they've confirmed that the same strain of Salmonella was present in the reptiles, but I assume that testing is underway.

Reptiles should not be present in households with infants. It doesn't matter if the animal never leaves its enclosure, because while the critter may not leave the enclosure, Salmonella will.

In low risk households (households without kids less than five years of age, elderly persons, pregnant women or immunocompromised individuals), good management practices can be used to minimize the risk of transmission of Salmonella, but given the potentially fatal nature of salmonellosis in infants and other high-risk individuals, these precautions are not adequate in high-risk households. While reptiles can be great pets, they're just not worth the risk in some situations.

Pet turtles and Salmonella...why am I not surprised?

Scott Weese — Sun, 01 Apr 2012 07:11:00 -0500

The CDC has announced an investigation of three multistate outbreaks of salmonellosis linked to pet turtles. At last report, 66 affected people had been identified, and since most outbreaks like this only identify a minority of cases, it's safe to assume there are many others.

Three different types of Salmonella have been implicated; S. Sandiego, S. Pomona and S. Poona.
Infected people have been identified in 16 US states (see map).
11 people have been hospitalized, but no one has died.
Most cases (55%) have involved children under the age of 10.
Almost all infected individuals who provided information about turtle contact with said the turtles were less than 4 inches long.

This ongoing outbreak, dating back to September 2011, has all the hallmarks of a pet turtle-associated outbreak: a large number of cases over a wide area and prolonged period of time, a predilection for young children, and the potential for severe disease. While far from novel, this outbreak also highlights some recurring themes.

The potential for widespread outbreaks from mass production and distribution of pets has been repeatedly demonstrated with a range of diseases, including recent examples involving chicks and guinea pigs. That doesn't mean that mass production is necessarily higher risk (although it certainly can be), but when something goes wrong, it can go very wrong because of the large number of infectious animals that get sent out.

Sale of turtles with shell lengths under 4 inches has been banned in the US since 1975. This is because small turtles are more likely to be handled (and potentially put in the mouth) by young kids. Despite extensive lobbying by US turtle breeders, the law remains in effect, but it's widely flaunted. It's surprising more efforts aren't put into enforcing this regulation given the number of people who are sickened every year from contraband turtles. (It's also surprising that infected people in the US haven't started large lawsuits against people distributing small turtles.)

Anyway, this is yet another reminder about the risks associated with reptiles and high risk individuals (i.e. young children, elderly, pregnant, immunocompromised) and the need for pet turtle owners to follow basic hygiene and infection control practices. More information about turtles - for owners, veterinarians and healthcare professionals - can be found on the Worms & Germs Resources page.