Maureen Anderson
Maureen Anderson is currently pursuing her PhD in the Department of Pathobiology at the University of Guelph. She grew up in Montreal, Quebec. In 1998 she moved to Guelph, Ontario where she completed her veterinary degree in 2003. Following some time in private practice, she returned to the University of Guelph for graduate studies in infectious disease and a residency in Large Animal Internal Medicine. She completed her thesis on methicillin-resistant Staphylococcus aureus (MRSA) in horses in December 2007, and earned her board certification with the American College of Veterinary Internal Medicine (ACVIM). As a post-doctoral fellow she helped to set up the Worms & Germs Blog and its many resource sheets before beginning her PhD work on infectious disease control practices in veterinary medicine. She lives in Guelph and has two cats named Bonnie and Clyde.
Murray Valley Encephalitis down-under - Help from the chickens
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
equIDblog has moved to Worms & Germs!
Unfortunately, because of funding challenges (translation... there was no more money), we were no longer able to maintain our equine infectious disease blog (equIDblog) as a separate site. However, based on the positive feedback we had and the amount of traffic on the original site, we still think it serves a role and are dedicated to maintaining equIDblog in some form. So, we are going to merge equIDblog with the Worms & Germs Blog. We have already moved the equIDblog Resources page, which can be accessed through the link in the title bar. We will also gradually move all of the current archived blog posts from the site and place them under the equIDblog topic category which can be found in the left index bar. Here we will maintain all of the site's current content and continue to provide information and commentary on equine infectious disease issues. Thanks to all of our loyal equIDblog readers for making the blog such a success, and we hope you'll continue to follow us here on the Worms & Germs Blog!
Study Seeking "Superbugs" In Horses
A two-part study (Maddox et al. 2011) was recently published online in the Equine Veterinary Journal looking at antimicrobial resistant "superbugs" in horses in the UK. The first part of the study had the simple objective of estimating the prevalence of both MRSA nasal colonization and fecal shedding of antimicrobial resistant E. coli in the UK horse population. The reason they were looking at E. coli is because this bacterium is part of the normal intestinal flora of most animals (including horses), so it's easy to find, and it is frequently exposed to antimicrobials whenever a horse is treated systemically (i.e. with either oral or injectable antibiotics), so researchers use it as an "indicator" for resistance that may develop in other bacteria as well. E. coli doesn't typically cause gastrointestinal disease in horses like it can in people, nonetheless E. coli is a common cause of uterine, urinary and wound infections in horses, as well as septicemia in foals, and antimicrobial resistant infections in these situations can certainly be a big problem.
Out of 678 nasal swabs (taken from horses on over 500 premises), only 4 (0.6%) were positive for MRSA. That's good to see, as it's very easy for MRSA to spread in a horse population "under the radar," because colonized horses do not have any outward signs that they are carrying the pathogen. The overall low prevalence in the community setting is similar to previous community studies in the UK and other areas. Out of 650 fecal samples, 452 (72.2%) were positive for an E. coli that was resistant to at least one antimicrobial. That's not too surprising. The bigger concern is that 233 (37.6% - over one third of all horses tested) samples contained multidrug-resistant E.coli (defined in this study as resistance to more than three antimicrobial classes) and 42 (6.3%) samples contained an E. coli that produced an extended-spectrum beta-lactamase (ESBL). ESBLs are particularly problematic because they can be relatively easily transferred between bacteria, they confer resistance to a large number of commonly used antimicrobials in the beta-lactam class (which includes penicillins and cephalosporins), and are frequently associated with genes that confer resistance to other antimicrobial classes as well. Bacteria that produce ESBLs are a significant problem in human medicine and have been reported to cause infection in horses as well.
The second part of the study used information collected from questionnaires filled out by the horse owners to try to determine risk factors that affected the odds of a particular horse shedding antimicrobial-resistant E. coli. They used some pretty heavy-duty statistical analysis because they were looking at so many factors and different outcomes, and any time that happens you have to take the final numbers with a grain of salt. Nonetheless, the results can help point the way for future studies to help determine which factors may have the biggest impact on the risk. The authors found recent hospitalization and veterinary treatment for various conditions over the last six months were associated with higher odds of shedding multidrug-resistant strains of E. coli, and the type of farm/facility also affected the odds. In addition, having a recently hospitalized horse on the premises (among other things) increased the odds of a horse shedding ESBL E.coli.
What does all this mean for the average horse owner? The results really aren't new or startling. We already know that antimicrobial resistance is a growing problem in equine medicine, as it is in veterinary and human medicine in general, and this is one more set of studies that provides evidence to that effect. I have no doubt that if a similar study was performed in North America the same kinds of resistant bacteria would be detected, although the numbers may vary somewhat one way or another. The second part of the study also re-emphasize the role that antimicrobial use plays in promoting development of and selection for resistant bacteria, and the potential for the treatment of certain horses to affect the microbes being carried and shed by the animals around them. In the end, it comes down to being responsible about how we use antimicrobials in order to curb the development of resistance, so that these important drugs remain effective for treating serious infections in the future. This applies equally to their use in people and animals of all kinds.
Who's Better At Biosecurity?
There are a lot of recommendations out there for establishing or improving sound infection control practices on horse farms, many of which can be found on this very blog. Some refer to such practices as "biosecurity," but what's done on horse farms compared to the often very strict biosecurity protocols at facilities such as swine or poultry operations (e.g. all-in all-out management, closed barns, shower in) is very different, so we prefer to call it an infection control program, rather than "biosecurity." Regardless, one of the biggest challenges with regard to infection control, in almost any setting, is getting people to comply with all the various policies and recommendations. Unfortunately, it's not enough to just tell people what needs to be done (that'd be too easy!) - knowledge by itself usually won't change people's behaviour. They also need to be motivated to change their behaviour, for example by the potential for a positive reward (e.g. they get to take their horses to shows) or the potential to avoid a negative outcome (e.g. their horses don't get sick). Furthermore, individuals need to really believe they are capable (physically and mentally) of performing the required tasks - if they don't think they can do it or be effective at it, they're unlikely to try. In reality, getting people to change their behaviour to adopt sound infection control practices can be quite complex.
A study soon to be published in Preventative Veterinary Medicine (Schemann et al. in press) looked at some of the factors that affect horse owners' biosecurity practices and perceptions. The study was performed in Australia one year after the devastating equine influenza outbreak that occurred in 2007, using an online questionnaire to which 759 horse owners responded. Each owner's biosecurity compliance was rated as low (30%), medium (20%) or high (50%) based on how often they reported using 16 different infection control measures.
Factors that were associated with low compliance or poor biosecurity practices included people who:
- were younger in age
- had two or more children
- were not involved with horses commercially
- had no long-term business impact from the 2007 equine flu outbreak
- were not fearful of a future outbreak of equine flu in Australia
- thought their current hygiene and access control practices were not very effective in protecting their horses
Now, studies based on surveys of this kind always need to be taken with a grain of salt, as the study population itself was difficult to define and the information was all self-reported by owners, which can lead to confounding and misclassification bias. Nonetheless, the results are still interesting and on the whole are consistent with behaviour theory. Those whose income and livelihood were not dependent on the horse industry, and those who were not fearful of another outbreak, would be less motivated to put the effort into infection control measures. Furthermore, those who felt that what they were doing already wasn't really effective (for whatever reason) would be less motivated to try harder because they can't see the benefit. It's quite possible (as the authors speculate) that having two or more children results in less compliance with infection control simply due to the time constraints associated with having kids. Lack of time to properly perform infection control procedures is a major barrier to compliance, even in human hospitals, particularly with understaffing issues. The lower compliance among young people is also common to studies looking at protective behaviour in human health, possibly because young people have a sense of certain degree of invulnerability that results in riskier behaviour overall.
When it comes to infection control, the old adage "a chain is only as strong as its weakest link" is very important to remember. Although 50% of the horse owners in this study reported having high biosecurity compliance, the 30% with low compliance could ruin all their efforts should another outbreak occur, by contributing to the transmission and propagation of the disease on their own farms as well as to others. Hopefully this study will help the horse industry and government identify specific groups (i.e. young people, those not financially dependent on horses) at which educational and motivational campaigns can be targeted in the future.
More mosquito-borne mayhem
The mosquito-borne diseases eastern equine encephalitis (EEE) and West Nile (WNV) continue to rear their ugly heads in the northeast as we get further into the late summer season during which they are most common.
On August 13 there was an unconfirmed report of a case of West Nile in a horse at Woodbine Racetrack, just north of Toronto. No additional details have been forthcoming regarding the severity of the infection or the status of the horse, if WNV infection has in fact been diagnosed. Nonetheless, the Ontario HBPA is urging horse owners to ensure the vaccination status of their animals for West Nile is up-to-date. Unfortunately, if horses are not already vaccinated at this point, even vaccinating them immediately may still leave them susceptible to virus for the next few weeks until they are able to fully respond to the vaccine. This news follows close on the heels of news reports regarding increased numbers of WNV-positive mosquito pools in various regions north of Toronto, and thus is not altogether surprising.
The first case of West Nile in a human in New Jersey was recently diagnosed in a man from Mercer County. Again, no additional details about the severity of the infection or the man's condition are available, but the public is once again being urged to protect themselves against mosquitoes by wearing long sleeves and pants, using insect repellant, and eliminating standing water in which mosquitoes may breed on their property. Elsewhere the death on August 14 of a four-year-old girl in New York from infection with EEE has been reported. She is the fifth person in New York state to die from the disease in 40 years. The girl first began showing signs of infection earlier this month, but the diagnosis of EEE infection was only reached last week. EEE has a high mortality rate in humans as well as horses. Just as infection in animals can act as sentinel indicators for disease risk in humans, these human cases indicate that WNV and EEE are active in these respective areas, and humans and horses alike are at risk of infection. Mosquito avoidance can help protect both, and in addition timely vaccination of horses can help decrease the risk of disease.
This Worms & Germs blog entry was originally posted on equIDblog on 17-Aug-11.
Lions and tigers and glanders
Glanders, a very serious disease of horses, donkeys and mules caused by infection with the bacterium Burkholderia mallei, has made the news again in a rather unusual manner – it has been reported as the cause of an outbreak in lions and a tiger at an Iranian zoo in Tehran.
The story goes that two Amur tigers arrived at the Tehran zoo from Eastern Russia in April 2010 as part of an exchange program between the two countries. The tigers were supposed to be used to help restore the tiger population in northern Iran on the Miankaleh nature reserve, but their living quarters there were apparently still not ready, and thus they were being kept at the zoo. One of the tigers died in December 2010.
And that’s were the story starts to get a little dicey. The Iranians claim the tigers were imported already carrying the disease, and that the last case of glanders at the zoo was 50 years ago. The tigers had already been at the zoo for eight months - although the incubation period for glanders can be months in some cases, it is normally only weeks. The Russians of course insist that the tigers were completely healthy when they were transferred – they’d been thoroughly examined and quarantined prior to being moved. (This makes the most sense to me, since transporting an animal such a long distance is a major stress and increases the risk of illness, and transporting an animal that is already sick would be even more risky. Not a chance I would take with two members of a species of which there are fewer than 900 individuals left in the world.) They also pointed out that a sick tiger from the cold regions of Russia would be much more likely to succumb to illness during the very hot Iranian summer, not during the winter.
Another report said that three lions at the zoo also died from glanders in the last two months, and subsequently another 14 lions were diagnosed with the disease, all of which were put down by the authorities. The main concern seemed to be the spread of the disease from the big cats to the feral cat population, and then to the human population. This second report states that “the tiger died after being fed contaminated meat, though it is possible it could also be related to the glanders.” Yet another report said that the tiger was infected with feline immunodeficiency virus (FIV - the feline equivalent of HIV).
Facts to keep in mind:
- Glanders is an highly contagious disease, and highly fatal (B. mallei is even classified as a Class B bioterrorism agent).
- Animals that do recover from the disease can become long-term carriers of B. mallei, and are a risk to other animals (and people). Prompt euthanasia of affected animals is therefore often the primary means of controlling outbreaks (but the bacterium is susceptible to antibiotics).
- The infection can be transmitted to other animals (and people), usually through close direct contact or contact with oral and nasal secretions and discharge from skin ulcers. It can also be transmitted by eating tissues from infected animals.
- The bacterium is killed by most disinfectants, and UV radiation (sunlight).
Glanders can affect species other than equids, including people and cats, however there is very little information available about glanders in any felids, let alone lions and tigers. Theoretically it might be possible for the disease to spread from the zoo animals to feral cats and then to people, but I don’t know how many feral cats are brave (or stupid) enough to wander into a lion enclosure. There’s also a possibility that a glanders-positive feral cat may have infected the zoo cats (but again, it would have to be very brave, or very stupid). It is also unclear what tests were used to confirm that the big cats were infected with glanders, and it is unknown if other animals at the zoo have been tested. Since this is typically a disease of equids (and has also been found in goats and camels), I would certainly be checking these animals first.
The big question is, where did the glanders come from in the first place? It seems unlikely that the tigers brought it from Russia, when the disease is actually endemic in Iran (even though they’d had no diagnosed cases at the zoo for many years). Is there a carrier animal in the zoo? Were the animals infected by eating contaminated meat? Was it brought in by feral cats? The source needs to be identified and addressed or animals will continue to be infected, which is particularly bad news for the kinds of rare species that may be found in a zoological collection. Some more details about the testing would also be appreciated – given the severity of this disease, and the severity of the consequences for positive animals (euthanasia), one needs to be as sure as possible that these animals are infected with B. mallei and not something else.
Photo: Amur Tiger (Panthera tigris ssp. altaica) (click image for source)
Lyme disease in Australia?
The world is certainly getting "smaller," especially in terms of infectious diseases. One example is the renewed controversy this month over the existence of Lyme disease in Australia. A Sydney man was recently diagnosed with the disease following his death, and now a doctor from Laurieton claims to have "absolute proof" of at least two other Australians with the infection.
Lyme disease is caused by infection with one of three species of Borrelia, previously all known as Borrelia burgdorferi. The disease is transmitted by a few specific species of ticks belonging to the genus Ixodes. It is relatively common in areas of North America (including some parts of Canada) and Europe where these tick species are also found. Ticks become infected by feeding on reservoir hosts, which are typically small mammals. Early signs and symptoms in people following a bite from an infected tick can include a rash, fever, headaches, tiredness and joint pain. The disease can be very difficult to diagnose because the initial signs are quite non-specific, particularly if the person does not report being bitten by a tick.
None of the tick species known to transmit Lyme disease are found in Australia, although there is one species of Ixodes tick there which some believe is a potential candidate for a vector. However, after testing some 12 000 of these ticks, evidence of Borrelia infection has still not been found. Also, none of the known reservoir hosts of Borrelia are said to live in Australia, and no other hosts have been identified.
The Laurieton physician, Dr, Mayne, claims he has "absolute proof" of Lyme disease in at least two of his patients, and says he has about 30 more patients with the disease as well. "Proof" is a very strong word. Not only is the disease hard to diagnose clinically, but there is also no perfect test that can detect infection for certain. Even the DNA test on which Dr. Mayne is hanging his hat can be prone to false-negative and false-positive results. The article also does not state whether or not the infected patients traveled outside the country and could have potentially picked up the disease in a Lyme-endemic area. Further investigation is needed before anyone can claim to have "proof."
So why am I writing about this situation on a zoonotic disease blog, when there hasn't even been any mention of pets, and the disease can't be directly transmitted between people and animals anyway? Because this is a perfect example of a situation in which physicians and veterinarians could potentially work together for the greater good, under the "one health, one medicine" banner. Dogs in particular can also be affected by Lyme disease. If the Australians really want to know if Lyme disease has made it to their shores - or perhaps some other tick-borne disease that mimics Lyme - then they shouldn't just be looking in people. By alerting veterinarians that Lyme disease or a similar condition is cropping up in humans, they can start to look for it in the animal population as well. If they're left unaware, Australian veterinarians may not consider Borrelia as a potential cause of illness in their patients and therefore not test for it. If pets also start testing positive for Lyme disease, then hopefully that would be communicated back to the human medical community to increase testing of suspect cases there as well. If more cases are identified, either human or animal, then further efforts could be taken to identify the tick source and reservoir hosts in Australia.
More information about Lyme disease and ticks in dogs is available in the Worms & Germs archives.
Image: The "classic" bulls-eye rash associated with a tick bite transmitting Lyme disease (source: CDC Public Health Image Library #9874)
Newborn killed by Husky
Another tragic dog bite incident has resulted in the death of a three-week-old baby in Quebec. The baby's mother (17) and grandmother (37) left the child alone in the house, strapped to her car seat on a chair, while they went outside for a smoke. There were also two Huskies loose in the house at the time. Although the women were only a few meters from the open door, and came back inside when they heard noise, by the time they reached the baby it was already too late. The paramedics found the baby "covered in deep bite marks and scratched.
It is unclear to whom the dogs belonged, as the mother and father of the baby were sharing the house with two other people. The baby's father (who was not home at the time of the attack) said that the dogs had been around ever since the baby was born and had never posed a problem. The dogs were not normally aggressive and "when strangers came to the door, they didn't even bark." He said "there was no sign that this could happen."
Dog bites are always bad, but in the case of small children in particular they can even be fatal. According to Statistics Canada, since 1990 there have been 28 fatal dog attacks in Canada, and 85% of those killed were children under the age of 12.
Dog bites often occur when people don't know how to behave around a dog, and dogs may bite out of aggression, fear, or rough play. A three-week-old baby strapped to a car seat would pose little threat to a Husky, and unfortunately we will likely never know what brought on the attack. Parents and family members need to realize that a new baby is a big adjustment for everyone in the household - and that includes pets. A dog that is normally "as good as gold" may react very differently to a small, wriggling, strange-smelling, crying baby that suddenly takes over part of the animal's home "territory." It is very important that pets and babies be introduced very carefully and slowly, and they should always be supervised. Dr. Enid Styles, a veterinarian and behaviourist, makes some very important points:
...Styles said it is possible the animal might have been startled by the child's crying or the baby might have been caught in the middle of a fight between the dogs.
In any case, a child should never be left unattended around dogs...
"Supervision needs to mean, really, that you are between your dog and your child," she said. "You can't be just on the other side of the room."
Both Huskies have been seized by the Humane Society, and tests will be done to to confirm which of the animals was responsible for the attack and whether it was suffering from any problems, such as rabies (which presumably means the dog will be quarantined for 10 days). It is likely that the dog responsible will be euthanized.
Photo source: www.cbc.ca
Ringworm at the OSPCA
Never a dull moment...
This morning the Toronto Star published an article about the intended euthanasia of 350 animals at a humane society in Newmarket due to an ongoing ringworm outbreak. This was quickly followed by another article about the same event that gave a few more details, including some comments from the OSPCA chief executive officer Kate MacDonald, who confirmed that the euthanasias had begun. A "very aggressive strain" of ringworm and "human error" (related to a breakdown in protocols) are currently being blamed for this morning's actions. A lot of people are (understandably) very upset. No one ever wants to see an infectious disease outbreak come to something like this.
I’m hesitant to comment too much at this stage, because we still don’t have all the facts - apparently even the duration of the outbreak is unknown. No one has said if all 350 animals are infected (or what percentage of them are), nor how many other animals are present at the shelter. We also don’t know what’s already been tried in terms of controlling the outbreak.
A few facts about ringworm (dermatophytosis) that people need to remember:
- Ringworm is a skin infection that can be caused by several species of fungi. It is not a "worm" at all. It is also very easily transmitted by direct or indirect contact with infected animals - their fur, their cages, their blankets, or anything else that may be contaminated with infected skin cells or hair. Such infectious material can even be spread over short distances (e.g. room to room) in dust that is stirred up into the air.
- Ringworm is transmissible to people, so with a large outbreak there are also issues with staff safety, and concerns with adopting out infected animals. For most people ringworm infection may cause itchy, uncomfortable skin lesions, but for higher-risk people (e.g. very young children, the elderly or immunosuppressed individuals) the infection can be much more serious.
- There are also a lot of animals (particularly cats) that carry ringworm without showing any signs of infection. If the Newmarket shelter has 350 animals with clinical signs of ringworm (a detail about which we have no information right now), that’s pretty bad, but even the animals who don't appear to be infected may be carrying the fungus and could spread it to others.
- Crowding, close contact and warm, humid environments are all factors that increase the risk of ringworm transmission. These are also all factors that are very hard to control in a crowded animal shelter.
- Ringworm is treatable, but it is not cheap or easy. Animals typically require systemic therapy (usually oral medication, which can be very expensive particularly in large dogs) as well as whole-body topical therapy (e.g. dips, shampoos, sprays), and they need to be treated for several weeks. Decontamination of the environment at the same time is critical to prevent reinfection.
Cleaning up a ringworm outbreak at a shelter with at least 350 animals is no small undertaking. The second article in the Star also describes personnel at the shelter this morning wearing "white hazardous material suits, latex gloves and plastic covers over their shoes", which would be considered reasonable precautions for entering a highly contaminated environment.
I'm sure we'll hear more about this in the days to come, and hopefully that will include more details about why the mass euthanasia was deemed necessary by the OSPCA.
For more more information about ringworm, download the information sheet from the Worms & Germs Resources page, or check out our archives.
Photo source: yorkregion.ontariospca.ca via www.thestar.com
World Hand Hygiene Day
Today is World Hand Hygiene Day, an occasion being promoted by the World Health Organization’s (WHO) “SAVE LIVES: Clean Your Hands” campaign. This WHO initiative is aimed primarily at improving hand hygiene in healthcare facilities around the world, in order to help reduce healthcare-associated infections (HAIs) (e.g. infections that people develop while in hospital). Also to mark World Hand Hygiene Day, the CDC has launched its new hand hygiene website, which has tons of information on hand hygiene basics, guidelines, resources for promotional campaigns, and information for patients.
Hand hygiene is one of the most important aspects of controlling infection in human hospitals, but that’s certainly not the only place where it can be beneficial. It is also very important in veterinary hospitals, to help prevent the spread of infection between animals, whether they’re sick or they’ve just had surgery. Here on the Worms & Germs blog, we also talk a lot about using proper hand hygiene to help prevent the spread of zoonotic pathogens from pets to people. Even at home, just like in hospitals, our hands are one of the most common ways bacteria and viruses move from one surface to another, from one person to another, and from just about anything into our mouths (either directly or via our food). Dirt on your hands is easy to see, and it makes it easy to remember to wash your hands. The bigger concern is the microscopic amounts of dirt and germs on your hands that you can’t see, and the best way to take care of that is really to make hand hygiene part of your routine. Make it something that just naturally goes along with playing with your pet, or cleaning the cat’s litterbox, or poop-scooping after your dog. Although most of the time it may not be a matter of saving lives, it’s certainly a matter of saving people from being sick. Make hand hygiene a habit, and don’t just do it for yourself – do it for all the people (and pets!) you live with and interact with everyday.
