Maureen Anderson
Maureen Anderson is currently a post-doctoral fellow 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 a year and a half in mixed animal private practice in Listowel, Ontario, 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 became board certified with the American College of Veterinary Internal Medicine (ACVIM) in the spring of 2008. She has two cats named Bonnie and Clyde.
Swine flu has gone to the birds
Just when all those turkeys that managed to survive Thanksgiving weekend thought their troubles were over, there's new issue: H1N1 influenza (formerly known as swine flu) has been found in an Ontario turkey flock. The H1N1 virus was first reported in birds in Chile in late August.
This is not a reason to panic. No one can get the flu from eating a properly-cooked Thanksgiving turkey (nor from any other type of properly-cooked turkey). The producer has voluntarily (and very responsibly) quarantined the affected flock, and no birds or eggs have left the facility. There is no risk to the food chain.
Pigs can be infected by human, pig and bird flu viruses, and multiple infections can result in viruses trading genes and producing new viruses that can infect more species. So it's not too surprising that H1N1can infect people, pigs and now birds as well. This incident serves as an important reminder that we need to remain diligent about infection control and hygiene, even around animals. It's highly unlikely that these turkeys had contact with infected pigs - most likely the virus was spread to this flock by a person. Poultry producers may therefore need to consider getting vaccinated for H1N1 flu not only to protect themselves, but also their flocks, and anyone who may have the flu should definitely stay off these farms. Hopefully the virus does not become established in wild bird populations (like H5N1 has in some areas), as this would make it much harder to control.
Recommendations for avoiding the flu (H1N1 or other) remain the same:
- Wash your hands and/or use alcohol-based hand sanitizer
- Sneeze into your elbow
- Disinfect commonly touched surfaces
- Stay home if you are sick
- Get vaccinated!
Canine lepto: It's that time of year again
The latest newsletter from the University of Guelph's Animal Health Laboratory contains a brief update on the percentage of positive MAT tests for canine leptospirosis that the lab has seen in the first half of 2009. Approximately 30% of the tests have been positive, which is up from the previous two years. However, the prime time for lepto cases (and therefore typically also lepto testing) is just starting: the cool damp fall weather provides a great environment for lepto bacteria to survive outdoors for the next several weeks.
Prevention of lepto in dogs, as with most diseases, is preferred to trying to treat sick animals. The best way to avoid the bacterium is to keep your dog out of areas where infected wildlife may urinate frequently, particularly out in the bush. But of course, skunks and raccoons can be found as close as the backyard as well, so even in the city the risk isn't zero.
If your dog does frequently go into the bush and is at increased risk for leptospirosis, hopefully you've already discussed vaccination with your veterinarian. While the vaccine available doesn't protect against all types of lepto, it does help protect against the most common ones - in Ontario, these are believed to be the lepto serovars grippotyphosa and pomona. We also received the following question from a reader the other day:
"Should a dog who has shown positive for early stages of kidney disease be vaccinated against leptospirosis? Can the vaccine accelerate the illness to acute renal failure?"
I can see where the question comes from, but the simple answer to the second part of the question is no. Although the infection can certainly affect the animal's renal function (and can push even healthy dogs into renal failure if it is severe), the vaccine works on the dog's immune system and does not affect the kidneys directly. The answer to the first part of the question is, of course, much more complicated, and depends on many other factors including the dog's overall health status, lifestyle and other risk factors, and vaccination history. The decision about whether or not to vaccinate your dog should be discussed on an individual basis with your veterinarian.
More information about leptospirosis is available on the Worms & Germs Resources page and in our archives.
Image: Scanning electron micrograph of Leptospira sp. bacteria (source: CDC Public Health Image Library ID#138))
Cooperating on Q Fever
Another surge in the number of cases of Q fever in people in the Netherlands has been reported. Prior to 2007, the average number of cases of Q fever per year in the country was only 15. In 2007 there were 192 cases, and last year there were 958 cases, making this the largest community outbreak of Q fever ever reported. At the beginning of May 2009, another jump in the number of cases - over 200 - was reported by the dutch newspaper de Volkskrant.
Q fever is caused by a highly infectious organism called Coxiella burnetii. The organism can be carried by many different animals, but particular sheep and goats, and sometimes cattle. Most of the time it does not cause a problem in these species, but it has been linked to abortions and abortion storms (i.e. when many animals in the herd abort in a short period of time). It can be shed in manure, urine and milk, but the largest numbers of organisms are found in birth fluids and tissues (e.g. aborted fetuses, placentae). When the tissues and fluid dry out, the organism can be stirred up into the air over short distances in dust. Humans are highly susceptible to C. burnetii, and inhaling even a single organism can cause infection. Most of the time people who get sick have signs very similar to the flu, but severe pneumonia and liver disease can develop in a small number of cases.
A definitive link between sheep and goats and the Q fever outbreak in people in the Netherlands has not yet been established, but it is highly suspected that many of the cases are associated with infected goats (and some sheep). In the last two years numerous outbreaks of Q fever have been reported on dairy goat farms and one dairy sheep farm in the Netherlands. This has lead to a cooperative arrangement between the Dutch agricultural ministry and the Dutch public health ministry - these two goverment branches have come together to help cover the costs of vaccinating sheep and goat herds in the country, in order to help stem the tide of disease and ultimately prevent more human cases. This is a great example of the "one medicine" concept, whereby groups on both the human health and agricultural/animal health sides are working together on this problem.
Manditory vacciation is now required for sheep and goats on larger farms in the hardest-hit areas, as well as any farms reporting any cases of Q fever since 2005, and any sheep or goats that have a "public function" (e.g. petting zoo animals or occupational therapy farms). It is very important that this last group is included under the manditory vaccination, as these animals have a large amount of contact with people. Steps have also been taken to improve hygiene, restrict spreading manure from sheep and goats, restrict visitors to infected farms, and to make abortion storms on sheep and goat farms reportable, so they can be investigated for Q fever. It will be interesting to see how effective these measures are at controling the outbreak in 2009.
More information on Q fever can be found in our archives.
Oprah's Parvo Pups
The latest issue of Oprah's magazine "O" features the icon talking about her recent puppy dog adoption drama involving canine parvovirus. It just goes to show that even the pets of the biggest celebrities in the world are not beyond the reach of common microscopic infectious pathogens.
A couple of months back, Oprah adopted two cocker spaniel puppies from a shelter in Chicago. Unfortunately, within two weeks they both came down with parvovirus infection and had to be hospitalized. I'm sure both dogs received top-of-the-line care with no expense spared, but even so one of the puppies died. The other puppy came very close to dying as well, but happily she apparently has now recovered completely and is doing just fine (or quite likely better than fine, considering who her new owner is!).
Oprah also mentioned how one of her other dogs, Solomon, also suffered from a parvo infection years ago, but that dog was over a year old when he became ill. It's actually quite unusual for any dog to get parvo beyond one year of age - most adult dogs are not affected by the virus, unless perhaps their immune system is compromised for some reason.
These stories bring up a few interesting points to ponder:
It's great to adopt an animal from a shelter and give a homeless animal a home. It is an act of great kindness that I don't want to take anything away from in the least. However, it's important to realize that you never know what shelter dogs may be carrying, nor how well vaccinated they are.
- Even if the animals are vaccinated once at the shelter, the protective effect may be less than ideal if a properly timed vaccination series is not completed.
- In this case the pups may have been exposed to parvo after leaving the shelter, but they could have just as easily been exposed at the shelter, which begs the question of what else might they have been carrying? Bacterial pathogens such as Salmonella and Campylobacter are also particularly common in young dogs and cats (even healthy ones), and these are potentially zoonotic agents.
Young animals, particularly from shelters, are higher risk in terms of the infectious diseases they can carry and transmit. That doesn't mean they shouldn't be adopted, but it does mean taking some extra precautions for the first several weeks they're in their new home. These include being very diligent about controlling stool contamination of any kind (which can be easier said than done during the house-training phase), preventing contact with high-risk individuals (e.g. young children, the elderly, anyone with a weakened immune system) and lots of handwashing on the part of everyone involved with the puppy (or kitten!).
Parvo is a very serious disease in puppies, yet people sometimes become a little complacent about vaccinating for parvo and other puppyhood diseases. Remember, though, that the reason parvo has become so much less common than it used to be is largely because of widespread and effective vaccination. I have to wonder about how well vaccinated Oprah's dog Solomon was to get the disease at the age he did, but there could easily be other factors involved as well. The virus is still out there, and if we become lax in our infection control practices - including decreasing exposure of puppies to the stool of other dogs, as well as vaccination - it's waiting in the wings for its opportunity to move in. Even with the very best care the infection can still be fatal.
It's also relevant to note that, as demonstrated by Solomon's case, just because parvo is very uncommon in adult dogs doesn't mean it's impossible for them to get it. It's important to always remain diligent.
Parvoviruses are quite species specific, so thankfully people cannot get parvovirus from dogs, but remember that puppies can get diarrhea from pathogens like Salmonella, which can be transmitted to people. There is also a human parvovirus which is the cause of Fifth disease. Just like the dog virus cannot infect people, the human virus cannot infect dogs.
Image source: http://omg.yahoo.com
Rhodococcus equi in horses and people
Rhodococcus equi is a very well recognized pathogen in horses – it is a common cause of pneumonia in foals between the ages of 1-6 months, and infection is also sometimes associated with other problems such as diarrhea, swollen joints and abscesses in other parts of the body. The infection can be very difficult to treat because the bacteria are able to live inside white blood cells, which helps protect them from the body’s immune system, and because they often cause abscesses to form, which are difficult for antibiotics to penetrate. Rhodococcus equi infection in foals has been studied extensively, but there’s still a lot we don’t know how the body defends itself against this organism. These are a few things we do know:
- Almost all foals are exposed to R. equi as neonates, but most of them never develop signs of infection.
- Giving newborn foals hyperimmune plasma (plasma with extra antibodies against R. equi) may have some beneficial effects on farms where the infection is a recurrent problem, but this practice is still controversial.
- Adult horses are essentially immune to the infection.
- In almost all cases if clinical disease in foals, the R. equi strain involved carries a special gene called vapA.
- Mortality rates in foals vary considerably from 0% to 30%.
- So far, efforts to develop a vaccine to help protect foals have been unsuccessful, but research in this area is ongoing.
People can also be infected with R. equi, and as in foals, pyogranulomatous pneumonia (infection of the lungs which results in the formation of many abscesses) is one of the most common conditions caused by this organism. However, there are a few important differences between infection in people and infection in horses:
- 85% to 90% of people with R. equi infection are immunocompromised, meaning their immune system is weakened or suppressed for some reason, e.g. HIV infection, or immunosuppressive drugs taken by organ transplant or cancer patients.
- Among people infected with R. equi who have normal immune systems (i.e. immunocompetent), about half of the infections are localized, meaning they only affect one small part of the body. Many of these are associated with wound infections.
- Only 20% to 25% of the R. equi isolates in people carry the vapA gene.
- Infection in immunocompetent people can be fatal in approximately 11% of cases, but among HIV-infected patients the mortality rate from R. equi infection can be as high as 50% to 55%.
Rhodococcus equi is actually a soil organism, and this is likely the most common source of the organism for both horses and people. Only approximately 1/3 of humans infected with R. equi report that they have had contact with horses or pigs (pigs can also carry the bacterium). So we don't know how much of a risk an infected foal is to a person. However, it is prudent for people, particularly those with weakened immune systems, to take precautions to avoid potential transmission of R. equi from horses.
- Try to reduce dust levels on the farm. Because R. equi most often lives in the soil, it can get stirred up into the air in dusty areas, which can then lead to inhalation by animals and people. Doing things like planting grass or other vegetation, installing windbreaks in high-traffic areas, or wetting down dusty stalls or paddocks can help reduce dust levels in the air.
- Keep open wounds and other broken skin covered when working around animals.
- Always wash your hands after handling a foal (or any horse)
- If you have a foal that develops signs of R. equi infection, make sure you have your veterinarian examine it as soon as possible so the diagnosis can be determined and the foal can be treated properly as soon as possible. Some foals with R. equi may develop severe pneumonia very quickly, so it’s important that they are examined right away.
Garden veggies and poopy parasites
Spring appears to have finally sprung in earnest in Southern Ontario (although we may still get one more frost on the weekend, so I hear) and people are getting back out into the garden. An increasingly popular trend in recent years, particularly this year now that the Obama's are doing it too, is vegetable gardening. Lots of people like the idea of growing their own veggies in their own backyard, or perhaps in a community garden plot for city dwellers who still want to get their hands dirty - it's economical, good for the environment, and the plants can be grown "organically" without the use of chemicals or pesticides. However, pesticides and garden bugs aren't always the only things to worry about having on your fresh veggies. We received the following comment from a Worms&Germs reader:
"...What if veggies get infected with raccoon stool[?] Can eggs be killed after [the] veggie is grown and ready to eat?"
Great question. The concern in the case of raccoon stool is the eggs of the roundworm Baylisascaris procyonis, which can be passed in huge numbers by a relatively high percentage of raccoons in many regions. If swallowed, the eggs release larvae which can migrate through the tissues of the body, rarely causing visceral, ocular or neural larval migrans.
The good news:
- Raccoons like to defecate in the same areas most of the time, usually on a relatively flat, elevated surface (e.g. woodpile). These areas become raccoon "latrines", and the soil in the area can become very heavily contaminated with roundworm eggs. The good part is that most raccoons therefore not defecate in your garden.
- Vegetables cannot become "infected" by the parasite - the eggs cannot be absorbed or otherwise get inside a vegetable, they can only contaminate the parts of the plant that are directly in contact with soil.
The bad news:
- Even though raccoons may not poop in your garden, they can still track roundworm eggs into the soil on their fur or paws when they come by to explore your crop, so you should always consider soil outside as potentially contaminated.
- Baylisascaris eggs are highly resistant to disinfectants and chemicals, so they can't be killed this way.
- Raccoon roundworms aren't the only parasites that may be found in garden soil. Dogs and cats can carry other roundworms (Toxocara spp.) which are also capable of causing larval migrans if swallowed (although infection with these worms in dogs and cats is not nearly as common as infection with Baylisascaris in raccoons). Cats in particular, unfortunately, do sometimes like digging in gardens and may sometimes use a garden as a litterbox.
- Soil, particularly if it's contaminated by the stool of any animal, can also contain many different kinds of bacteria such as Salmonella. Even if you can somehow protect your garden plot from animals, purchased garden soil and fertilizers may contain or may have come in contact with animal stool somewhere along the way.
So how do you make your garden veggies safe to eat?
- Wash wash wash: Because Baylisascaris eggs are so difficult to kill, the best thing to do is physically remove them from all surfaces of your vegetables by washing thoroughly to remove all visible dirt before doing anything else. If you cut into a vegetable before washing it, the soil on the outside can contaminate the inside.
- Peel peel: Peeling vegetables ensures that all dirt (including any dirt stuck in tiny crevices on the vegetable's surface, or dirt you may not be able to see with the naked eye) is removed prior to consumption, but it's still crucial to wash the veggie first (and your hands) before peeling.
- Cook: From an infection control perspective, it's best to cook vegetables before eating them. This actually won't do anything to Baylisascaris eggs - these have to be removed by washing and peeling - but it does help kill bacteria that either contaminated the veggies out in the garden or that contaminated the veggies during their preparation in the kitchen. For those of us who like our nice crunchy vegetables, obviously cooking them won't do, therefore washing and peeling become that much more important.
And, of course, always wash your hands thoroughly with soap and water after you've been working in the garden, even if you wear gloves.
In a lot of urban areas, it's hard to prevent raccoons and other animals from getting into yards and gardens. There are things you can do to discourage raccoons from hanging around your house, and if raccoons establish a latrine on your property it must be very carefully cleaned up. For more information on Baylisacsaris, raccoons and cleaning up raccoon latrines, please see our archives.
Worms & Germs - Thanks to our readers!
The Worms & Germs blog has officially been active for one year, and look how far it’s come! Just last week we surpassed 100 000 unique hits since our launch. We now regularly have over 1000 unique hits on the site per day during the week, and the numbers are still growing. The current swine flu outbreak has emphasized once again the importance of zoonotic diseases in the world today, and the diminishing division between human and animal health. It's great that we're able to provide a reliable source of information about zoonotic infectious diseases to such a wide and diverse audience.
Everyone involved in Worms & Germs would like to take this opportunity to thank all the visitors who come to our site, and especially those who keep coming back for more! Please continue to help us spread the word about zoonotic disease control and safe, responsible pet ownership. Questions, comments and suggestions are always welcome! -Scott & Maureen
Swine flu: What about the pigs?
.jpg)
We've been talking a lot about the swine flu outbreak the last few days, but so far all we've really talked about are the human aspects. The reason we're blogging about it on this site is that it's a zoonotic disease - so where do the pigs fit in?
There's a distinct lack of information about where this strain of the influenza virus actually came from. I heard on the news this morning that one person who was interviewed by a CNN reporter was even trying to blame Canada for the outbreak, claiming that it was Canadian tourists that introduced the disease to Mexico in the first place! While I'm sure there will eventually be a great deal of investigation into how the outbreak got started (for the moment I think everyone's more worried about trying to just keep it under control), it's quite possible that we'll never find the "index case" or know exactly from where it came. But one thing's for sure: somewhere along the way, there has to be some pigs involved.
Pigs are the great "mixing pot" of influenza viruses, particularly with regard to avian, human and swine versions of the pathogen. Pigs can be infected by strains of all these different types, and coinfections (infection with more than one influenza virus at the same time) provide the viruses with a prime opportunity to trade RNA and recombine to form new influenza strains with new properties - more infectious, more virulent, or perhaps better able to infect another species, for example. In this case we appear to have a swine influenza virus that is not only capable of being spread to people (as occasionally happens with "regular" swine influenza viruses), but also between people, and hence the developing human outbreak.
But what about the pigs? There isn't a lot of information out there at the moment, with all the focus on the human aspect, but so far Mexican authorities have found no infected pigs in Mexico (at least no where they've looked - so far). Influenza in pigs is really nothing new, and other swine influenza strains are commonly found in pigs around the world. Highly pathogenic strains, like those that cause massive devastation of poultry flocks, don't occur in swine. If an influenza virus gets into a pig barn, however, it's like putting a person with the flu in a crowded room - the virus spreads very quickly through the air over short distances and soon everyone (or every pig) has the flu. Thankfully the virus generally also moves on quite quickly, and after a few days the animals generally start to recover. While such an outbreak certainly affects their growth efficiency, very few (if any) pigs die.
Yesterday the Canadian Veterinary Medical Association (CVMA) distributed a fact sheet on swine flu from the Canadian Food Inspection Agency (CFIA) for all Canadian veterinarians and swine producers. The CFIA is encouraging increased vigilance with regard to monitoring and diagnosing disease in Canadian pigs, to prevent the disease from spreading through the swine population. In addition to emphasizing vaccination, good hygiene practices and biosecurity, particularly around sick pigs, they also point out that it's equally important (especially now) for anyone who may have the flu to avoid contact with pigs (be they Canadian pigs or pigs in any other country), in order to avoid spreading the virus to them. Hopefully people in other countries will take the same precautions.
Another very important point is that swine influenza is NOT a food safety concern. The virus does not survive well in the environment for very long, and therefore cannot survive on pork products, and certainly cannot survive proper cooking (which is always very important for any kind of meat). The fact that some countries are banning pork imports is really not going to do anything to help control the outbreak - the concern should only be about live pigs (and people). So you can still have pork sausages at your next spring barbeque, just ask anyone who's feeling "under the weather" (or a little flu-ish) to please stay home!!
More on Avian Influenza
.jpg)
Wild birds are the natural hosts of all influenza type A viruses, of which there are numerous subtypes distinguished by their hemagglutinin (HA – 16 types) and neuraminidase (NA – 9 types) surface proteins. Subtypes H5, H7 and H9 can infect both birds and humans, but H7 and H9 infections in humans are uncommon. Within subtypes H5 and H7 there are both low pathogenic and highly pathogenic strains. Highly pathogenic strains can cause severe illness in both domestic birds and people, and death rates are high, although many wild birds (particularly water fowl) seem to be resistant to disease even from these more virulent viruses. Both sick and seemingly healthy birds can shed the virus in their respiratory secretions and droppings, and contact with this contaminated material can spread the virus to other birds. Transmission of the currently circulating avian influenza viruses from birds to people is uncommon. Fortunately, person-to-person transmission of avian influenza is uncommon.
The big worry with influenza viruses is that they have a high propensity to "mutate" - sometimes they change slowly (i.e. antigenic drift), and sometimes they change quickly (i.e. antigenic shift). When two different influenza viruses infect the same animal or person, the different components of each virus can recombine to make a new virus that will share some characteristics of both the original viruses. For example, if a highly pathogenic avian influenza virus (like the H5N1 virus from Asia) were to recombine with a human influenza virus, it could create a virus that causes severe disease like the avian virus, but which can be readily transmitted between people. This would create the potential for a serious outbreak of severe, even fatal illness in people.
Highly pathogenic avian influenza of either the H5 of H7 subtype is reportable in many areas of the world (including Canada), due to the potential for massive mortality in domestic bird flocks, as well as the risk of severe illness in people should such a virus start to circulate in the human population. Since 2004, avian influenza has been detected in Canada four times - highly pathogenic H7 types were found in British Columbia (2004) and Saskatchewan (2007), and low pathogenic H5N2 viruses were found twice, also in British Columbia (2005, 2009). The latest outbreak in January 2009 resulted in the destruction of 60 000 birds on the BC premises where the virus was originally detected, as well as all the birds on a second premises where the virus was found just over two weeks later. This disease is taken very seriously, and the response to these outbreaks by the Canadian Food Inspection Agency (CFIA) must always be swift and definitive.
The risk of highly pathogenic avian influenza to the general public in countries such as Canada that are (usually, though not at the moment) considered free of the disease is very low. The virus cannot survive in poultry products (i.e. meat, eggs) that are properly cooked. Contact with wild birds (dead or alive), particularly migratory birds that could potentially be from other continents, is likely the highest risk. Pet birds are also susceptible to these viruses, so its important to prevent them from coming in conatct with wild birds as well, especially because owners have such close contact with their feathered friends.
More information on influenza in animals and people is available in our archives.
Testing for ringworm with toothbrushes
If your veterinarian suspects your pet may have ringworm, there are several different ways he or she may test for the causative fungus (a dermatophyte) on your animal's fur and skin. Some of these techniques are more useful than others in different situations.
- Wood's lamp: A Wood's lamp is simply a special ultraviolet light. Approximately half of all Microsporum canis strains (the most common species of dermatophyte that causes ringworm in cats and dogs) will fluoresce blue-green under such a light. This type of testing is obviously very easy to perform. However, other debris in an animal’s hair coat may fluoresce as well, and other species of fungus that cause ringworm do not fluoresce, so this test is not useful by itself in most cases.
- Microscopy: Sometimes ringworm fungus can be seen on hair shafts from an infected pet when examined under a microscope. However, it is easy to confuse other debris and structures for dermatophytes. Also, not every hair on an infected animal will carry the fungus, so it's possible to miss the infected hairs altogether with this test.
Fungal culture: The best way to diagnose ringworm is to culture the fungus from the infected individual (person or animal). In animals, one of the best ways to collect a sample for culture is to comb over all the fur and skin with a new toothbrush, and then try to grow dermatophytes from the toothbrush. This allows the fur from all over the animal to tested, rather than just one little clump of fur plucked from one area. It can also make it easier to get a sample from the face and paws of cats, which is where these animals often carry the fungus. Although fungal culture is the best way to diagnose ringworm, remember that fungal culture takes much longer than bacterial culture – instead of days, it may take up to three weeks to grow some dermatophytes.
It's also important to remember that dogs, and more often cats, may carry dermatophytes on their fur even when they look healthy. A positive fungal culture from an animal with skin disease, particularly a cat, does not necessarily rule out other diagnoses, so your veterinarian may still recommend other tests as well. However, any animal with ringworm should be treated to prevent spreading the infection to other animals and people.
More information about ringworm is now available on the Worms&Germs Resources page, and in our archives.
