Worms and Germs Blog

Norovirus from dogs?

Scott Weese — Wed, 01 Feb 2012 21:35:00 -0500

Norovirus sucks. It's been a while since I had it, but it doesn't conjure up fond memories. A bunch of Canadian tourists returning from Cuba (and presumably all of the other people on their planes) can also attest to the unpleasant nature of this viral infection.

Norovirus in people is (logically) caused by human norovirus. There are some other types of norovirus that infect other species, but the human version predominantly infects people. Predominantly doesn't mean always, though, and other hosts of the virus need to be considered. A recent study published in the Journal of Clinical Virology (Summa et al 2012) looked at whether human norovirus could be found in dogs. Researchers collected fecal samples from 92 indoor pet dogs in Finnish households where people had vomiting and diarrhea or where the dog owner had had close contact with someone with norovirus. Fecal samples were tested for the presence of the virus using molecular tests.

Norovirus was detected in feces of 4 of the 92 (4.3%) canine fecal samples. All positive dogs were from households that had more than two sick people. Additionally, kids were present in all households with positive dogs. Two of the dogs had been sick, with nausea and loss of appetite. Illness in the dogs was pretty mild and only present for one day, and it's not clear whether norovirus was responsible. Fecal samples from owners were only available from one of the positive households, and there the same norovirus strain was found in the owner and the dog.

These results are interesting and indicate that a small percentage of dogs in contact with people with norovirus can shed the virus. The big question is, "what does this mean?" That's not so clear. Finding norovirus in the dogs' feces is one thing. Determining that it's relevant to human (or animal) health is another, and it's important not to over-interpret the results, because...

The testing that was used detects norovirus RNA, i.e. genetic material from the virus. That means that the virus passed through the intestinal tract. It does not necessarily mean that live virus was present, since this type of testing detects both live and dead virus. Dead virus obviously poses no risk to anyone.
Even if live virus was being passed in the dogs' feces, the amount of virus coming out the rear end of the dogs isn't known. It might be pretty low and therefore of less concern.
The relative risk posed by the household dog is a big thing to consider. All dogs that were shedding the virus were from households with multiple sick people, therefore they were already in pretty biohazardous environments with lots of virus being tossed around (in many different ways). This suggests that it may take a lot of exposure for dogs to shed (potentially only a little) virus. Also, it minimizes the relative risk posed by the dog, since if only dogs from severely affected households shed the virus, the dog is only one of many possible sources and probably of lesser risk than exposure to sick people and environmental surfaces they contaminated. Dogs from households with active disease are probably not very likely to encounter lots of other people or dogs (probably less so than the people in the house), therefore limiting their potential role in transmission. There's no evidence that dogs are long-term carriers of norovirus.

Does this change what you should do if you have norovirus? Not really. It means you should try to limit contamination of the environment, wash your hands frequently, stay away from others as much as possible and avoid puking on your pets. Maybe we should add "keep your dog isolated along with you," just in case.

Another interesting finding was the association between sick kids and norovirus-shedding dogs. It's further evidence of the "kids are biohazardous" theory. We know that kids are at increased risk of various infectious diseases. At the same time, we have previously shown that contact with kids is a risk factor for dogs shedding Clostridium difficile and MRSA. Whether that's because kids are more likely to be shedding these bugs, they have closer contact with pets, they pay less attention to hygiene or a combination of these isn't clear, but this result isn't particularly surprising. (No, I'm not recommending banning kids from pet-owning households. As parents, we know our kids are effective disease vectors... that's just part of having kids.)

This study doesn't tell us whether pets are sources of human norovirus, and we really shouldn't expect it to. A single study rarely answers all the questions, and good studies sometimes raise more questions than they answer. This is an interesting study and it shows that more work is indicated to clarify the answers to the questions raised above, and to determine whether there is any real concern about dogs and this nasty virus.

Dogs as a source of yeast infections?

Scott Weese — Sat, 28 Jan 2012 07:53:00 -0500

An article in the Winnipeg Free Press by Dr. W. Gifford-Jones, MD, talks about recurrent yeast infections in women. It covers several pertinent points, such as the fact that lots of women who think they have yeast infections actually have different types of infections, and that over the counter treatment might be a concern because of the lack of a proper diagnosis.

Why mention that here? Because of a little anecdote at the end of the story (and one that's gathering the most attention).

'My colleague, faced with repeated failure, decided to ask if his patient had an animal living with her. She replied she did have a small dog and the dog did, in fact, enjoy the comforts of her bed on many occasions. But that was nothing new. It was only after intense probing that she finally admitted with embarrassment to teaching her dog a trick. Since she was away all day at work, she had taught the dog to urinate in the bathtub! The dog had a yeast infection!'

Good for them for thinking about pets. It may have taken time to get there, but at least the question came up. However, this may be yet another example of finally asking the question but stopping the thought process too soon.

Was the pet a possible source of recurrent yeast infection in the person? I can't discount the possibility. We really don't know much about the potential for transmission of this kind of infection, but the pet could have been contaminating the bathtub, leading to subsequent exposure of the person.

Did the pet really have a yeast infection? That's an important question, since they just finished saying a lot of women who think they have a yeast infection don't actually have one. I wonder whether the yeast infection was properly diagnosed by a veterinarian.

Was there any evidence that, if they both had an infection, the same bug was involved? Probably not. However, if you really want to know if the pet is potentially involved, a culture of both the pet and owner to see if the same yeast is present would be needed. Is it really worth doing? Perhaps, because if the pet and person have different yeast, it means that the MD needs to keep looking for possible causes of recurrent infection.

Could the pet have been getting infections from the owner? Possibly. If a pet and person have the same infection, and it's not an infection that classically originates in a pet, then you have to consider the direction of transmission. If the woman had recurrent yeast infections, she could have been regularly contaminating the tub, where the dog could have been exposed when peeing.

It's an interesting case that should raise some questions and hopefully lead to more thought about pets as a potential source of infection in cases like this, but at the same time, a more thorough investigation as well.

BC's not-so-West Nile case

Scott Weese — Wed, 25 Jan 2012 18:35:00 -0500

Following reports of a veterinarian warning colleagues and horse owners about West Nile infection in a British Columbia horse, Dr Brian Radke, a Public Health Veterinarian at the BC Ministry of Agriculture, has clarified the situation.

"The BCCDC co-ordinates WNV surveillance for the province of BC including monitoring of mosquitoes, birds, horses and humans. The BC Ministry of Agriculture supplies information to BCCDC on horse cases. In Canada, equine cases of WNV are reportable the Canadian Food Inspection Agency (CFIA).

The CFIA has no reports of WNV consistent with the Prince George horse. Discussions with the veterinary practitioner have clarified that the horse's illness, which occurred in November, was not due to WNV.

The testing discussed in the article was not conducted at the provincial government animal health laboratory. The BC Ministry of Agriculture is following up to determine the nature of the WNV testing and the appropriate interpretation of the test results.

BCCDC WNV surveillance indicates the following:

In 2011 no humans, mosquitoes, or birds were detected with WNV infection in BC. One horse in the Central Okanagan was reported as positive and that report is under review.
There have been no positive WNV indicators in the Prince George area.
In BC, WNV has been detected in southern parts of the province, all below N50 latitude. (By comparison, Prince George is N54 latitude.)
Risk modelling by BCCDC suggests that Northern BC, including Prince George, experience insufficient sustained heat during the short summer for WNV to amplify and be transmissible by the low density of vector mosquito species.
The risk modelling also suggests that even in the warmest (that is, southern interior) areas of the province, the risk of WNV infection decreases significantly in September as the vector typically ceases seeking blood meals.

The BC Ministry of Agriculture and BCCDC look forward to working with the province's equine practitioners to interpret WNV testing results and epidemiology to assess the risk of WNV to horses in the various regions of BC. The assessment of risk could then inform decisions about the appropriate interventions for WNV infection in horses in the various regions."

We thank Dr. Radke for the information.

Severe Pasteurella infections from palliative pet care

Scott Weese — Wed, 25 Jan 2012 14:50:00 -0500

Pasteurella multocida is a bacterium that's commonly found in the mouths of dogs and cats. It's a common cause of cat and dog bite infections in people, but can also be spread through close contact with pets (without bites). It's logical to assume that the closer the contact, the greater the risk of transmission. A recent report in Clinical Infectious Diseases (Myers et al 2012) describes three people with life-threatening Pasteurella infections. A unique aspect was all three people got sick from nursing dying pets.

Case 1

A 55-year-old woman with sore throat, fever and difficulty swallowing was diagnosed with epiglottitis (inflammation of the epiglottis, a part of the throat region) and hospitalized. Pasteurella multocida was identified on a blood culture. It was subsequently revealed that she had provided palliative care to her dying dog. As part of this, she was dropper-feeding the dog honey, and also eating honey with the dog from the same dropper.

Case 2

A 63-year-old woman with sore throat, difficulty swallowing and hoarseness was diagnosed with uvulitis (inflammation of a different part of the throat region) and narrowing of her airway. As with Case 1, P. multocida was isolated from her blood. Her cat had died six weeks earlier and she had "continuously held, caressed, hugged and kissed her cat during its last 7 days of life."

Case 3

A 66-year-old woman was hospitalized with fever, chills, cough and difficulty breathing. She had severe pneumonia and P. multocida was grown from a sample of respiratory secretions. Two weeks before she got sick, she had provided palliative care for her dying cat, by "holding, hugging, and kissing the head of the cat and allowing the cat to lick her hands and arms."

Fortunately all three women recovered from their infections, but the severity of disease is certainly a concern. As is common, there was no attempt to see whether the implicated pets actually carried the same Pasteurella multocida strain as the owners, but here the authors at least had a good excuse, since all of the pets had died before the owners got sick.

There are some interesting points in the Discussion section of the paper.

"Our 3 patients’ histories of having recently provided palliative pet care to their dying animals were obtained only after P. multocida was identified in cultures and only after subsequent detail-oriented, animal contact histories were obtained."

Pet contact (or animal contact in general) is still not asked enough by physicians investigating unknown illnesses. It's unclear whether it would have made a difference in these cases, but knowing more and knowing it earlier can help speed the path to the right diagnosis. Here, pet contact was only considered after a pet-associated bacterium was identified.

"Simply asking whether or not the patient had a pet would not have uncovered the defined association of these respiratory illnesses with palliative pet care. The patient with P. multocida uvulitis even denied having a pet (it had died 6 weeks previously) and only admitted to having provided palliative pet care when asked specifically if she had any animal contacts in the past 3 months."

This shows some of the challenges and how care must be taken when asking about pet contact. Simply asking "Do you have a pet?" doesn't cover it.

"Only diligence and very detail-oriented, pet-related histories will likely uncover further patients with invasive P. multocida infection related to the pet owner’s provision of palliative pet care to dying animals."

This shouldn't be focused on palliative pet care, since that's a minor component of pet contact. Many other people have close contact with their pets, even when the pets are healthy. It's something that should be considered at all times.

West Nile warning for BC horses

Scott Weese — Tue, 24 Jan 2012 10:48:00 -0500

A Prince George, British Columbia veterinarian is warning other veterinarians and horse owners about West Nile in the province. Little information is available at this point, but the warning is in response to a diagnosis of West Nile infection in a horse from the area. The report calls it a "deadly disease" but it would be more appropriate to call it a "potentially deadly disease," since most horses that are exposed don't get sick, and many sick horses recover. I don't want to downplay the seriousness of West Nile, but it's important to keep it in perspective and make people panic.

The BC CDC has an ongoing West Nile surveillance program because of the obvious concern as this virus has worked its way across North America over the last decade. While it's taken it's time getting to BC, West Nile virus has been identified in the province, and only time will tell whether it becomes a serious health concern for horses or people. The latest update of the BC CDC surveillance data indicates one positive horse, but no positive humans (of 415 tested) or mosquito pools (2282 tested). The one equine case that was documented was from Central Okanagan. The horse had clinical signs consistent with infection, although the severity and outcome are not reported.

It's unclear to me whether this Prince George case is something that's happened just recently or whether the horse was sick. It's pretty late in the year for a mosquito-borne virus, but not impossible in some areas.

Does this report mean that horse owners in BC should be concerned? Maybe. "Aware" might be a better term.

Horse owners and veterinarians always need to be aware of the infectious disease risks in their area, and areas to where a given horse may travel. Keeping apprised of ongoing West Nile virus surveillance can help determine the likelihood of exposure, but that doesn't mean you can wait until there's a case next door before you do anything. (Someone has to have the first case in an area, and you don't want that to be you.)

Whether or not to vaccinate against this virus depends on the likelihood of exposure and risk aversity. Available vaccines are rather safe and effective (not 100% on either account, like any vaccine, but quite good overall), and vaccination decisions should be made based on a well-reasoned discussion between veterinarian and owner, considering a variety of factors such as where the virus has been found and how much risk everyone is willing to take.

The news report has a quote recommending vaccination in the spring. That's the typical time people vaccinate against mosquito borne diseases, but that's not my recommendation. For me, the goal is to vaccinate so that peak immunity is present at the time when exposure is most likely. West Nile virus is classically a late summer/fall disease, based on mosquito types and their biting patterns. For that reason, I like to see horses vaccinated a little later in the year - closer to the high risk period. Again, it's important to know disease trends in each region to make the most informed decision.

So, horse owners in BC should be aware but not panic. A good discussion about vaccination and about general mosquito avoidance practices should be the first thing that happens.

More on MRSA and meat

Scott Weese — Tue, 24 Jan 2012 08:09:00 -0500

While it shouldn't come as a surprise considering other studies, a recent study in PLoS One (O'Brien et al 2012) has caused a bit of a stir in the US. This study, headed up by Dr. Tara Smith's research group in Iowa, looked for methicillin-resistant Staphylococcus aureus (MRSA) in retail pork. They bought pork from different stores in Iowa, Minnesota and New Jersey, and tested it for the presence of MRSA. They focused on pork because MRSA can be found widely in pigs internationally, including in the US.

Not surprisingly, they found MRSA. Overall, they tested 395 pork samples from 36 stores, including both "conventional" pork (300 samples) and "alternative" pork (95 samples). The latter consisted of samples labelled "raised without antibiotics" or "raised without antibiotic growth promotants." MRSA was found in 6.6% of samples; 6.3% of conventional pork samples and 7.4% of alternative pork samples.

When they looked at the MRSA types that were present, 27% were the ST398 "livestock-associated" MRSA that's most commonly found in pigs. However, like our earlier Canadian studies, they found common "human-associated" MRSA strains more often. These strains can also be found in pigs, albeit less commonly than ST398, and it's unclear whether meat contamination with these strains comes from pigs or from people who handle the meat throughout the processing chain.

The fact that there was no difference between conventional and antibiotic-free pork isn't surprising to me, although it catches some people off-guard because of some basic over-assumptions about the relationship between antibiotics and MRSA in food animals. We can find MRSA quite commonly on both regular and antibiotic-free farms. While it's reasonable to assume that antibiotics were a key factor in driving the emergence of MRSA in pigs, there's not much evidence showing that ongoing antibiotic use is an important factor in determining whether MRSA is present on specific farms or in specific pigs. One potential explanation is that in order to control infections, farms that stop using antibiotics start using other substances such as zinc in feed to help control overgrowth of certain intestinal bacteria, and these compounds may be just as effective at selecting for certain resistant bugs as classical antibiotics. That's just one possible explanation, but it shows how complex the issue of antibiotic-resistance is, and it shows that simply saying "stop using antibiotics," without really looking at the overall problem, won't necessarily reduce MRSA.

What does the presence of MRSA in food mean? Who knows? MRSA is a pretty high profile bug, and with good reason, because it's a very important cause of infection in people. A key aspect of MRSA in food is that cooking food will kill the bacteria (as well as many of the other harmful bacteria that often contaminate raw meat). So proper attention to food safety, including thorough cooking, cleaning of surfaces, prevention of cross-contamination and hand hygiene, should greatly reduce any risk (the problem is a lot of these things aren't usually done very well).

Murray Valley Encephalitis down-under - Help from the chickens

Maureen Anderson — Wed, 18 Jan 2012 08:50:00 -0500

Although the weather in Southwestern Ontario seems quite confused lately regarding whether it wants to be winter or spring, at least we're still a few months off from having to worry about mosquitoes and the viruses they carry once again. Warmer parts of the world, however, are in the midst of their mosquito season, and some chickens are lending a hand to give people in the area a "heads up" about what's around.

The Health Department of Western Australia has detected Murray Valley encephalitis virus (MVEV) in chicken flocks in East Kimberley. The department has also tested and found the virus in its sentinel chickens in Wyndham and Kununurra. These sentinel birds play an important role as an early warning system when viruses like MVEV are circulating in the area. Just like West Nile virus, MVEV typically circulates between birds and the mosquitoes that like to feed on them, but problems occur when the same mosquitoes start to bite people (or other susceptible animals such as horses), particularly when there are a lot of mosquitoes, like when the weather is very wet or when there's been flooding. Although most people who are infected with MVEV or WNV fight off the virus with no difficulty, or may simply develop short-term, non-specific signs of illness like mild fever and malaise, in some people these viruses can cause severe infection of the brain (encephalitis) and may even be fatal.

Knowing that MVEV has been found in these "guardian" chickens lets people know (via warnings issued by the health department) to take extra precautions against mosquito bites, such as:

Staying indoors during peak mosquito activity - dusk and dawn
Wearing protective clothing including long-sleeves and long pants
Applying insect repellent

In North America, you can pretty much substitute West Nile for Murray Valley in a case like this. Sentinel chickens have been used to provide early warnings of circulating WNV here, before cases are detected in people or horses. Another means of early detection that is also used is testing pools of mosquitoes directly.

It just goes to show you can still be an important part of the country's defenses, even if you're a little chicken :p

(click image for source)

Bordetella infection from cat to child

Scott Weese — Tue, 10 Jan 2012 14:22:00 -0500

Case reports of infections acquired from pets are sporadically found in the human medical literature. A common problem with these reports is the failure to look for true evidence of zoonotic transmission. The typical thought process is "We found this bug in a person, it's most often found in animals, so this person must have gotten it from their pet." Often, this likely is actually the case (although some evidence would be nice). In other instances, like the Pasteurella bone infection described in the Orthopedics paper I wrote about recently, this assumption is probably completely off-base.

Something that is usually missing from these reports is any investigation of the suspected pet. Finding the bacterium in question in/on the pet, and showing that it's the same strain as was found in the person goes a long way to supporting the conclusion that the pet was the source. It's not a 100% guarantee, since you can't say whether it went from pet-to-person or person-to-pet, but with a typically pet-associated bacterium its much more likely to have come from the pet, so finding the same strain in both pet and person is pretty solid evidence. Most case reports don't bother even trying to get this much information (but they still get published...).

A case report in an upcoming edition of Zoonoses and Public Health (Register et al 2012) is another example of a study that provides some information about a potential pet-associated infection, but stops short of the type of proof that is needed. To their credit, the pet wasn't available for testing and they are clear that it's a "possible" case of zoonotic transmission, which puts them a step up on other studies, but it's still too bad the additional information couldn't be reported.

The case report describes an 11-year-old girl with cystic fibrosis (CF). People with CF are at greatly increased risk of respiratory infections, including infections caused by microorganisms that typically don't cause disease in other people. This child had a sputum sample collected during a routine doctor's visit, when she didn't have any signs of respiratory infection. Bordetella bronchiseptica, a bacterium most often found in dogs and cats (and one of the causes of kennel cough (aka canine infectious respiratory disease syndrome) in dogs), was isolated from the sample. When this was explored further, it was revealed that child's family had obtained a new kitten three weeks earlier, and the kitten had signs of respiratory disease.

Unfortunately, the kitten had been removed from the household by the time B. bronchiseptica was diagnosed in the girl, so it couldn't be tested. (They don't say why the family got rid of the cat.) However, the authors at least took it a step further and did some detailed molecular characterization of the bacterial strain they recovered from the sputum sample. Different genetic traits suggested that the strain was feline in origin, and, combined with the fact that the child had contact with the kitten, this provided a little more support to the hypothesis that the cat was the source. It's not proof, but still interesting. They also determined that the B. bronchiseptica strain was missing a gene that's associated with helping cause disease, suggesting it's not as able to make people sick. That might explain why the child was carrying the strain in the absence of disease, although people can carry lots of different bacteria that can potentially cause disease without being clinically ill.

In the end, it was an interesting little report and the authors conclude with a couple of good statements:

"Acquisition of detailed clinical and epidemiological data paired with discriminatory genetic comparison of case isolates and contact isolates is needed to more firmly establish transmission patterns and identify likely contact risks." (A fancier way to say what I said above.)

"...it seems advisable to counsel CF patients regarding adherence to practices that minimize opportunities for zoonotic transmission of B. bronchiseptica from family pets or other potentially infected animals."

Headshaking and equine herpesvirus

Scott Weese — Sat, 07 Jan 2012 18:55:00 -0500

Headshaking is a frustrating problem in horses. It's often hard to identify a cause and treatments are frequently unrewarding. Many different possible causes of headshaking have been proposed, including equine herpesvirus type 1 (EHV-1) infection.

As is common with herpesviruses, EHV can lie dormant in the body, and it may be re-activated during times of stress. There's ample evidence that other herpesviruses can cause nerve pain with reactivation. In humans, re-activation of the varicella-zoster virus (the herpesvirus that causes chickenpox) causes shingles, which is a very painful disorder. Since dormant EHV-1 can be found in nerves in a horse's head, it has been suggested that pain caused by reactivation of dormant virus could be a trigger for headshaking.

A recent study published in the Journal of Veterinary Internal Medicine (Aleman et al 2011) investigates this theory. The researchers looked for the presence of EHV-1 in trigeminal ganglia (a group of nerve "nodes" in the head) in headshaking horses and healthy controls. While it was only a small study, there was no evidence indicating a role of EHV-1 in headshaking, since the virus was only detected in 1/8 headshakers compared to 0/11 controls.

This study doesn't absolutely rule out EHV-1 as a cause a headshaking, since it still could be one of many potential causes that is involved in only a minority of cases. However, this study suggests that EHV-1 is not a particularly common cause of headshaking, if it causes it at all.

Bearded dragon leads to gravy Salmonella contamination

Scott Weese — Sat, 07 Jan 2012 08:05:00 -0500

No, not gravy made from bearded dragons (a type of reptile), but foodborne Salmonella with a link to the reptile.

Reptiles are an important source of Salmonella, which is why standard guidelines recommend that high-risk people (e.g. children less than 5 years of age, elderly individuals, people with compromised immune systems, pregnant women) not have contact with reptiles or have them in the house. A report in Zoonoses and Public Health (Lowther et al 2011) highlights another possible risk.

The report describes a Salmonella outbreak that was traced back to a potluck dinner. Nineteen cases were identified, 17 primary cases (people that attended the dinner) and two secondary cases (household members of people that attended the dinner). Overall, 29% of people that attended the dinner got sick. A further 18 people had some intestinal disease but strictly speaking didn't fit the definition for a case (however it is suspected that they were part of the outbreak). Salmonella subspecies IV (a type mainly associated with reptiles) was isolated from the stool of five people, confirming the occurrence of an outbreak.

As is typical, food consumption history was evaluated. Sixteen of the 17 primary cases reported consuming turkey gravy, which was a statistically higher proportion than that of people who did not get sick. The gravy was made at the private home of a person who didn't attend the dinner. This was the only home of the people involved where reptiles were kept. Two healthy bearded dragons lived in the house, in a terrarium in the living room.

The investigation focused on the reptiles, since the Salmonella strain found is typically associated with reptiles, and the turkey (the source of the gravy) had no evidence of Salmonella contamination based on testing. Samples from the environment of the household where the gravy was made were collected, and two types of Salmonella were identified. One of these Salmonella types (Salmonella Labadi, which was different from the outbreak strain) was isolated from one of the bearded dragons, as well as the inside and outside of the terrarium glass, other terrarium surfaces, surfaces around the terrarium, the bathroom sink drain and kitchen sink drain.

A common question that comes up when people have reptiles and high risk people in the house is "If I don't take the critter out of the cage, I should be ok, right?" Unfortunately, that's not true. Human Salmonella infections have been clearly identified in situations where reptiles don't leave the terrarium because (as was the case here), while the reptile may not leave the terrarium, Salmonella often does.

The person who made the gravy said that the bearded dragons had not been out of the terrarium when food was being prepared. A child was responsible for feeding the reptiles and cleaning the terrarium, and was supposed to use the bathroom for terrarium cleaning. However, it was reported that the reptiles' dishes "might have" been cleaned in the kitchen sink during the the day period when food was being prepared for the party.

The overall conclusion was that this outbreak "probably resulted from environmental contamination from bearded dragon faeces." It's a reasonable conclusion. Even though the same Salmonella strain wasn't found in the reptile, it makes sense because the reptiles were the most likely source of environmental contamination in the household, and that was the most likely source of the foodborne contamination. Reptiles can shed various Salmonella strains and they can shed intermittently. It takes multiple samples over time to get a real idea of the scope of Salmonella shedding, and I assume that one or both of these reptiles were shedding the outbreak strain at some point.

How can something like this be prevented, since the standard recommendation of having high risk people avoid contact with reptiles doesn't apply to this type of situation?

Good hygiene practices should be used when handling reptiles and their environments. In particular, there should be proper attention to hand hygiene after contact with reptiles or their cages.
Reptiles should not be allowed in the kitchen. Ever.
Food and water bowls should not be cleaned in kitchen sinks. Terrariums should not be cleaned in kitchen sinks. Ideally, they shouldn't be cleaned in bathroom sinks either. (If possible they should be cleaned outdoors with a hose.)
Good food handling practices are critical. Here, gravy wasn't re-heated to a high enough temperature to kill the contaminating Salmonella. Adequate re-heating would have prevented this outbreak.

Bat slaughter = Hendra virus control?

Scott Weese — Fri, 06 Jan 2012 08:52:00 -0500

Bob Katter, an Australian Member of Parliament and leader of the Australian Party, has proposed culling flying foxes (fruit bats) as a way to control Hendra virus, which is spread by these large Australian bats. He's not the first person to make such a proposal, but it's a knee-jerk reaction that in reality doesn't make a lot of sense.

It's not completely clear whether Mr. Katter is proposing a plan to completely eradicate the flying foxes altogether, or to simply let people kill any such bats they find on their property, but neither approach is likely to be effective in terms of decreasing the risk of Hendra virus transmission.

If people kill flying foxes on their property, they'll just be replaced in short order by bats from neighbouring areas.

Trying to eradicate the entire species is a bad idea for a variety of reasons:

Tinkering with a complex ecosystem doesn't often turn out the way you want it to. Australians certainly know from past experiences that bad things can happen when new species are introduced (rabbits are just one example). The same might happen when a species is removed.
Eradication of the species is probably impossible or at least very difficult. I don't know much about the reproductive rate of flying foxes, but if the species can reproduce at a reasonable rate, they can probably replace the culled animals unless people are really aggressive and seek out all remote breeding sites. The limitations of culling have been clearly shown in rabies control, where it doesn't do much because culled dogs are quickly replaced by new dogs.
Eradicating flying foxes would be very expensive. What could that money do if put into research on vaccination, treatment, and other worthwhile ventures? What if efforts were focused on eliminating flying fox roosting sites in horse pastures? Overall, the impact would probably be much greater.

Why stop with flying foxes? Australia has lots of nasty critters, ranging from spiders to saltwater crocodiles. Should we kill all of those too? Dog bites kill more people than Hendra every year. Should we kill all dogs?

Hendra virus is not something to ignore. While infections in horses are rare, they are usually fatal and there's the risk of transmission to people. Human infections are very rare but often fatal. So, ways to reduce infection of horses as a means of reducing both human and horse disease are important, but the slaughter of flying foxes doesn't make a lot of sense.

Shelter Giardia outbreak from birds?

Scott Weese — Fri, 06 Jan 2012 08:15:00 -0500

The Redlands Animal Shelter in California is looking into bird control measures after blaming Giardia infections in dogs on exposure to wild bird poop. On Facebook, Redlands Friends of Shelter Animals have declared "We have a serious problem with birds at the shelter. They land on the kennels and poop goes into the water bowls and give the dogs giardia - which is a parasite that gives them explosive diarrhea."

Giardia is a protozoal parasite that can cause diarrhea in dogs and other species. It can also be carried by healthy dogs, at relatively high rates in some groups. The scope of the problem at the Redlands shelter isn't clear since the news article only talks about one case. Whatever the scope, shelter management is blaming the birds.

Apparently, discussions are underway with different companies about a solution to the bird problem, something that is anticipated to be expensive. However, it's all too common for people to jump the gun on expensive interventions when there's an outbreak and overlook the root causes. While news reports don't always give the whole story, I'd be wary about blaming birds without much more evidence.

Can wild birds carry Giardia? Yes. However, there's more to the Giardia story than that. It doesn't sound like they've actually tested the bird feces to determine whether Giardia is there. Additionally (and critically) it doesn't sound like they've determined the type of Giardia that's infecting the dogs. There are different types (assemblages) of Giardia and most have a limited range of species they can infect. The vast majority of dogs with Giardia in most regions are infected by Assemblage D, a dog-specific strain that comes from other dogs and poses no risk to people. I'm not aware of Assemblage D being found in birds. Dogs can also be infected by Assemblage A, a type that infects people, and also can infect birds.

So, if Assemblage D is involved, they need to look at transmission between dogs within the shelter. If Assemblage A is involved, they still need to focus on dogs but could investigate birds as a potential source.

Overall, Giardia transmission is much more likely due to breakdowns in cleaning, disinfection, hand hygiene and general shelter practices rather than birds pooping in water bowls. It's a lot cheaper to address these shelter management practices (which will also help control various other infectious diseases) rather than dumping a lot of money into controlling bird exposure when in fact that may not be causing the problem. Trying to reduce exposure to bird poop is a good thing as a general practice, but it's important to focus efforts and resources on finding and addressing the true root problems during an outbreak.

More information about Giardia can be found on the Worms & Germs Resources page.

Human rabies imported from Haiti

Scott Weese — Thu, 05 Jan 2012 20:00:00 -0500

Last summer, I wrote about rabies in person from New Jersey, and now the full report about the case is available.

The unfortunate victim was a 73-year-old Haitian women. She initially went to an emergency room with a complaint of right shoulder pain, chest pain, headaches and high blood pressure. Difficulty swallowing was also noted when she was given pain medications, but she declined further testing and was discharged. It's not surprising that rabies wasn't considered at this point, although I doubt she was asked about animal contact or animal bites as a routine history question.

The next day, the woman went to two different emergency rooms, complaining of shortness of breath, spasms, hallucinations and balance problems. A cause was still not readily apparent, and over the next couple of days, her condition deteriorated, with development of more neurological abnormalities including tremors and mild seizures. Encephalitis (inflammation of the brain) was diagnosed, and a range of potential causes were ruled out. A nuchal skin biospy was collected for rabies testing but she was declared brain dead by the time results were obtained.

The strain of rabies that was identified most closely matched a canine rabies virus variant from a person in Florida who acquired rabies in 2004 while in Haiti. Upon further investigation, a cousin recalled that the person had been bitten by a dog in Haiti a few months earlier. The bite wasn't considered severe and medical attention wasn't sought.

As an almost invariably fatal infection but an almost completely preventable disease with proper medical care, education is a key aspect of rabies control, and that's where most of the breakdowns occur. This person didn't seek medical attention after the bite, because the bite wasn't too severe. Unfortunately, mild bites can transfer rabies just like severe bites, and any bite needs to be investigated as a potential source of rabies, particularly in highly endemic areas.

Canine rabies is a major problem internationally, accounting for tens of thousands of human deaths each year. Canine rabies has been eradicated in the US, meaning the canine rabies virus strain is no longer circulating. That doesn't mean dogs in the US can't get rabies, since they can be infected with various wildlife strains, but there is not a circulating pool of canine rabies virus like in some other regions. Canine rabies is still endemic in Haiti, although there have been efforts to control it through education and vaccination of dogs and cats in the country (where less than 50% of dogs and cats are vaccinated).

People living and traveling to rabies-endemic regions like Haiti need to be aware of the potential risk of rabies and consider any dog bite a possible rabies exposure. Similarly, healthcare workers need to query animal exposure and animal bites as a routine practice, since as with this case, rabies can be hard to diagnose initially.

(click image for source)

Petting Zoo E coli outbreak

Scott Weese — Thu, 05 Jan 2012 15:08:00 -0500

It's been a while since I wrote about petting zoos. Part of the reason is that the state of petting zoos in this area has improved quite a bit over the past few years, so I haven't been coming home from fairs or other events with a need to vent. However, improvements are not universal, and even with improved conditions, there are always going to be disease risks associated with petting zoos and other events where people have contact with animals.

This week's edition of Morbidity and Mortality Weekly Reports (a rather gruesomely named but very interesting publication by the US CDC) describes a 2011 outbreak of E. coli O157 from a North Carolina State Fair. After receiving reports of infections in four people who had attended the fair, an investigation was launched. Here are the highlights:

A total of 25 suspected cases were ultimately identified. (Usually, there are many more milder cases that go undiagnosed). Stool samples were collected from 19 of these individuals and the same strain of E. coli O157 was confirmed in 11 of them.
Affected people ranged from 1-77 years of age.
Eight people (32%) were hospitalized. Four of those had hemolytic uremic syndrome (HUS), a severe form of disease caused by E. coli O157.
When compared to people who did not get sick, having visited one of the buildings were sheep, goats and pigs were housed for livestock competitions was the only risk factor identified. While the public was not supposed to have contact with animals in those buildings, 25% of people reported having had direct contact with animals anyway.

An investigation like this often can't determine the source of the pathogen with 100% accuracy, because the investigation occurs after the fact (sometimes long after). That means the animals aren't around anymore for testing, the area/fair may have been cleaned up already, and people may not completely (nor accurately) recall exactly what they did. Regardless, it's quite suspicious that contact with this particular building was the root of the problem. How people became infected isn't clear. Some had direct contact with animals, and that's an obvious potential source. Cattle are the most common source of E. coli O157, but it doesn't appear that any were present in the building. Sheep and goats are a more likely source than pigs. Other people could have been infected through contact with contaminated surfaces in the building, something that has been documented in other outbreaks.

After a large 2004 petting zoo outbreak at this same fair, the state passed a law (named Aedin's Law, after a child who became seriously ill) that set strict requirements for animal exhibits where contact with the public is intended. This facility was not subject to Aedin's Law because animal contact was not intended (even though it was apparently common) and a multiagency task force is looking into additional measures for exhibits where animal contact might occur.

Cost/benefit is an important issue when it comes to infectious disease control. There will always be some risk of disease when interaction with animals is allowed. We can take measures to reduce the risk, but never eliminate it. Therefore, the key is maximizing the benefit and minimizing the risk. Animal contact at fairs and similar events can be very rewarding for some people, so most people will accept some degree of risk. This outbreak involved a relatively small number of people, particularly when you consider approximately 1 million visitors attended the fair. The infection rate was really very, but with a potentially life-threatening disease, it's not something that should be ignored.

As is the case here, infection control is often reactionary, with changes only taking place after problems occur. However, it's good to see that actions are being taken (at least in NC) to reduce the risk of this happening again.

Bad 2012 for Hendra virus in Australia

Scott Weese — Thu, 05 Jan 2012 11:18:00 -0500

While you don't want to read too much into a single case, 2012 has started off in a bad way for Queensland horses. Hendra virus was identified in a Townsville area horses that died. This zoonotic viral disease is largely restricted to Queensland, Australia, but it has a high fatality rate in horses (and people). Hendra virus is spread by fruit bats and is an ever-present concern to Queensland horse owners and veterinarians, but a mid-summer infection is quite unusual (remember that it's currently mid-summer in Australia). Most cases tend to occur from July to September - this case is a reminder that seasonal trends are just that: trends, not absolute rules.

Fortunately, the attending veterinarian used proper precautions when handling the horse to limit the risk of zoonotic transmission of Hendra virus. However, there will presumably be an investigation to determine who had contact with the horse and their potential for exposure. There is currently no way to prevent or specifically treat Hendra virus infection. An experimental antiviral treatment has been tried in the past, but it's effectiveness if far from clear.

Last year was quite bad in terms of the number of Hendra cases that were detected in Australia. Let's hope this early 2012 case isn't a sign of things to come.

Niagara (NY) SPCA under scrutiny

Scott Weese — Sun, 01 Jan 2012 08:16:00 -0500

The executive director of the SPCA of Niagara is under pressure from charges that he's "presided over the killing of hundreds of animals." As is common with shelter controversies, sorting through the emotion and rhetoric is difficult. At best, running a shelter can be a thankless task, due to the overwhelming number of animals, emotion, lack of understanding by the public (and often personnel) of the relevant issues, financial challenges and often poorly designed facilities. At the same time, bad things do happen in shelters, and it's critical to put in the time and effort to determine whether things are being done poorly and what needs to be fixed. Here are some of the issues from the Niagara situation.

"From Oct. 1 to Dec. 15, the local SPCA euthanized 473 cats and 100 dogs, a staggering total of killings, according to sources familiar with the situation at the Lockport Road shelter."

Apart from the problem of relying on information from anonymous sources, it's hard to put this number into context. You need to know the overall number of animals that come in and the shelter's capacity. It's a sad fact that about 50% of cats are euthanized at most shelters internationally because of massive overload. Shelters shouldn't be cat warehouses. It does no one (including the cats) any good to stockpile huge numbers of cats that never have a chance of adoption, and it creates a perfect environment for disease outbreaks. So, while that number of animals seems high at first glance, it may just reflect the reality of supply and demand, shelter capacity and the health/adoptability status of the animals.

"When he was hired, Faso admitted, “My animal care experience is very minimal.”"

A shelter director doesn't need to be an expert in shelters and animal health. In fact, some excellent shelter directors have come into the job with no experience whatsoever. Their job shouldn't be running animal care. They should be running the shelter, managing personnel, raising funds, liaising with the community and doing a host of other activities. The key is having good veterinary and animal care support, and a willingness to listen to those people. It would be great if every shelter manager was a veterinarian with a shelter medicine residency under his/her belt, along with an MBA and training in communications, but that's not going to happen. Someone with little animal knowledge but the ability to listen and take advice can be an excellent shelter director.

"McAlee and others tell horror stories of animals brought to the shelter for surrender or picked up on the streets and in need of medical care, who are then left to suffer in their cages. In one case, a cat that appeared to be suffering from a broken jaw was brought in and allowed to stay for a week in a cage without treatment. Finally, a concerned staffer took the cat to an emergency veterinary clinic where it was treated and then returned to the shelter."

That's a big problem. If true, and if this was done because of pressure from the director overriding advice from medical staff, then that's completely inappropriate. Interference with medical decisions and medical care does occur in some shelters and is a major problem.

"When the cat then developed a common respiratory infection, rather than provide further medication for the animal, Faso directed that it be euthanized."

This is a tougher issue. I hate to see potentially treatable animals euthanized, but euthanasia is an appropriate response in some situations. If they are unable to properly manage an infectious case or are overwhelmed with healthy cats, keeping an infectious cat may pose a huge risk to all of the other cats in the facility. It's impossible to say much here without more details.

"Other sources tell the Gazette that cats at the shelter have been injuring themselves in out-dated display cases and that a donor offered to fund the replacement of those cages. Faso, reportedly, refused to accept the donation."

Poor housing is a common problem in shelters. Good cages are expensive. It would be bizarre for a shelter manager to turn down money (that came with no strings attached) and if that was done, it would be another sign that Mr. Faso's not right for the job.

"..he has reportedly told board members and others that the local SPCA will “never be a no-kill shelter because it’s too expensive."

That's an unfortunate fact. No kill shelters just aren't viable in the grand scheme of things. Individual shelters can be no kill, but that's often done by cherry picking the adoptable animals.

It comes down to math. If 50% of cats coming into shelters are euthanized every year because of lack of space, to convert to a no-kill approach we'd need to massively increase shelter capacity every year to accommodate the increasing population. Millions of dollars would be required to create cat warehouses where millions of unadoptable cats lived marginal lives in facility confinement until dying of natural causes or from the massive disease outbreaks that would be certain to happen. I know I'll get reams of emails complaining about this paragraph, but to me it's a simple fact. If you increase supply by 100% per year by not euthanizing any animals, and demand doesn't increase, the math quickly shows you the size of the problem that would be created.

The only way to get to the point where no-kill is a viable approach is to have more responsible pet owners and better animal population control. Euthanasia rates are much, much lower in dogs, in part because of much better population control and also because people tend to try harder to recover lost dogs compared to lost cats. Recovery rates of lost dogs that make it to shelters are very high. Cats... not so much.

So, if you want to help out shelters and the animals in them:

Spay and neuter your pets.
Donate to good quality shelters to help them provide optimal care.
Volunteer, if you have the time and interest.
Hold shelters to a high standard, but make sure it's a realistic standard.
Encourage municipalities to properly fund animal shelters and enforcement.
Consider adopting from a shelter if you are getting a new pet.
Take the time to learn about the issues, and make assessments based on fact, not just emotion.

More US bat rabies

Scott Weese — Sun, 01 Jan 2012 08:01:00 -0500

Following on the heels of a case of bat-associated rabies in a South Carolina woman, a Massachusetts man has contracted rabies. Little information is currently available, although authorities state that they believe he was exposed by a bat in his home. News reports state that he's in critical condition but it's unfortunately very unlikely that he'll survive. Family members are receiving post-exposure treatment, however it's unclear whether this is because of concern for exposure from the infected man, or from the bat.

While these two cases don't represent a rampant rabies epidemic, it shows that there is still a long way to go with education of the public about bats and rabies. Rabies is a disease of extremes. It is essentially 100% preventable in people if exposure is identified and managed properly. It's also almost invariable fatal once disease sets in.

Variable pet bite advice

Scott Weese — Thu, 29 Dec 2011 09:14:00 -0500

It seems like pet bite articles come in waves, with a recent cluster showing the variable quality in advice that's available.

Often, they are holiday "filler" articles that provide some basic useful information but overall are of limited use or even harmful based on their very superficial approach. They often mention rabies, get a quick quote from a veterinarian or someone in public health, but don't emphasize the potential problems that can occur with even apparently minor bites. The thing that often raises my ire is the common statement about watching the bite and going to a doctor if your limb swells up or has pus oozing out, without talking about the need for proper post-bite care to actually prevent that from happening.

Anyway, I came across a couple of better articles recently, that get some good information across in a nice, readable manner. One, an article in "The Herald News" entitled "Cat bites always require check by doctor", gets a very important point across quickly.

The news story details the saga of the PJ, a 13-year-old cat, and his owner. PJ bit the woman on the arm causing a seemingly minor wound, but by the next day, her arm was red and swollen, necessitating a round of intravenous antibiotics and four days in hospital. In the article, Gail Steele, an infection prevention nurse, states "Cat bites.. must always be considered medical emergencies. This is especially true when they occur in the hand because that area has a richer blood supply...Their sharp little teeth are like little needles, and they inject bacteria right into soft tissue..."

This is a pretty extreme example of what can happen after a cat bite, but it's far from rare. It's not really clear whether this person's infection would have been prevented with normal practices. Bites over certain sites, like the hand, foot, joints, tendon sheaths and prosthetic devices, and bites to young kids, elderly individuals and people with compromised immune systems typically require prophylactic antibiotics.

If this was actually a bite over the arm, as reported, antibiotics might not have been given, even though cat bites are much higher risk for infection than dog bites. However, the key is that bites should be assessed so proper determination can be made about the need for antibiotics. All infections won't be prevented but appropriate medical care should reduce the risk and also allow for adequate consideration of whether rabies exposure might be a concern.

There's a sad end to this article, as PJ bit his owner again a few months later. The bite was over the shin and, given her previous problems, antibiotics were provided. However, the owner still ended up with an abscess that required surgical intervention and took months to heal. (Whether this person has really bad luck, whether PJ has a particularly bad mix of bugs in his mouth or whether the owner has an unidentified problem with her immune system is unclear, but back-to-back severe infections is a major issue, especially with a cat that is prone to biting.) The woman's daughter ended up taking PJ home with her, but after another unprovoked bite, he was euthanized.

Cat bites aren't always this bad, and in fact, most don't result in complications. However, that's not to downplay the potential problems. When you consider how often cats bite, how often cat bites are not properly cared for because they appear to be minor, and the ability of a cat bite to inoculate bacteria deep into the tissues, it's easy to see how bad things can happen. Reducing the risk of cat bite infections involves a few basic steps:

Reducing bites. Good handling and training (of both cats and people) can reduce the likelihood of bites. This is particularly important with kids, who may be bitten through rough or excessive handling of a cat.
Bite first aid. Prompt cleaning of the wound can reduce bacterial contamination. Thorough cleaning with soap and water can have a big impact on the likelihood of infection.
Medical care. Bites over certain sites or to certain individuals (see above) almost always require antibiotics. There's less consensus over other types of bites, but getting medical care is a good idea in any case to determine if there are any factors that indicate a need for antibiotics.
Rabies avoidance. Every bite should be reported to public health so the rabies aspect can be covered. The biting animal needs to be identified and observed for 10 days. If it's healthy after 10 days, it couldn't have been shedding rabies virus. If the biting animal cannot be identified, it's likely that post-exposure treatment for rabies will be required.

More snake smuggling

Scott Weese — Tue, 27 Dec 2011 15:09:00 -0500

I avoided the "snakes on a plane" title, as ever since the (bad) Samuel L. Jackson movie came out, every reptile smuggling headline seems to use use it. Regardless, would you like to be on a long trans-Atlantic flight with 247 smuggled animals, including a collection of venomous vipers? Probably not.

Fortunately for passengers on a flight from Buenos Aires to Madrid in early December, security screeners took note of the "organic substances moving inside" Karel Abelovsky's baggage. Inside, they found over 200 reptiles and mollusks, including 15 venomous vipers. Among these were two yararas (Bothrops jararaca), a viper that can grow up to 160 cm (~5 ft) in length, and which is a common cause of snakebites in some regions. Two of the animals were dead by the time they were found. Probably many (or most) of the others would have died during transit.

Animal smuggling is a big problem for many reasons:

It's an major animal welfare issue, since it is reasonable to suspect that only a small minority of smuggled animals survive the process, and even fewer thrive in their new homes.
Smuggling of endangered species can threaten survival of some species in the wild.
Smuggling of venomous or otherwise dangerous species can put people at risk. This includes people that purposefully buy dangerous animals but can't handle them, people who buy them not knowing they are dangerous, people at various points of the smuggling process (e.g. security screeners) that might come across the animals, and the general public who can be exposed if the animal escapes.
Moving animals between regions always carries some risk of bringing along infectious diseases. The less control, the greater the risk.

Mr. Abelovsky has been changed with smuggling and faces up to 10 years in prison, but typically people get off with minimal punishment. Weak enforcement and the potentially lucrative nature of smuggling means that it's going to continue until the problem gets taken more seriously, both in terms of investigation and charging of other people in the process (e.g. where did he get the animals, who was he working with, where were they going to go?) and application of penalties that are severe enough to discourage people.

Unfortunately, while an incident like this gets a lot of attention, it just represents the miniscule minority of smugglers that actually get caught.

Do surgeons have too much time on their hands?

Scott Weese — Thu, 22 Dec 2011 10:16:00 -0500

Sometimes poor quality papers get published, like the one I wrote about yesterday. Other times, published studies have no impact on science… and occasionally, that’s done on purpose. Two recent studies highlight the latter group and show that, while surgeons may have too much time on their hands, some at least have a sense of humour.

A "groundbreaking" study by Dr. Denis Verwilghen and friends was just published in the Veterinary Record, entitled “Investigation of the best suture pattern to close a stuffed Christmas turkey”. Their randomized trial involved assessing skin disruption scores and the cosmetic appearance of 15 stuffed turkeys that were closed with one of five different methods. Their conclusions: Before cooking, both the Utrecht suture pattern and surgical staples provided the best cosmetic result. However, after cooking and removal of the suture or staples, the skin only remained intact in the surgical staple group. Surgical staples are also a lot easier and quicker to place, so if you have a surgical stapler on hand, pull it out for your Christmas turkey. Beware though: the authors made sure to remind everyone that skin staples are not digestible. Maybe we need a surgical checklist for turkey preparation that requires the cook to record the number of staples that go in and are later taken out.

There was also a study published in the British Medical Journal (Subramanian et al, 2011) entitled "Orthopedic surgeons: as strong as an ox and almost twice as clever? Multicentre prospective comparative study." This authors investigated the standard claim that orthopedic surgeons are "strong as an ox but half as smart." The study (conducted by surgeons, so I have to wonder if they made up some of the data) involved comparing dominant hand grip strength and intelligence test scores of orthopedic surgeons and anesthetists. The end result? Orthopedic surgeons have a higher mean intelligence score and higher mean grip strength.

There are 3 possible explanations:

Surgeons really are smarter than we think. That may not be an acceptable answer since, as an internist, I’d have to make up a new series of surgeon jokes.
Anesthetists were a bad control group. The surgeons may have feared going up against their internal medicine counterparts, and therefore decided to compare themselves to the anesthetists instead.
They lied. Although, if they really are only half as bright as an ox, they must have had help.