Maureen Anderson

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Maureen Anderson grew up in Montreal, Quebec, and moved to Guelph, Ontario to complete 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, which she completed in 2008. She now works for the Ontario Ministry of Agriculture and Food (OMAF) as Lead Veterinarian, Anima Health and Welfare, focusing on issues bridging animal health and public health. She lives in Guelph and has two cats named Bonnie and Clyde.

Articles By This Author

Communication done right: EVH-1 in Minnesota

Two cases of EHV-1 have been detected on a farm in Prior Lake, Minnesota.  There aren't a lot of details about the cases, other than one horse was put down, and the other was taken to the University of Minnesota veterinary hospital for treatment and has apparently recovered and is ready to come home.

The barn is being monitored by the Minnesota Board of Animal Health for the next three weeks, which is the typical recommended quarantine period after the last case has either been removed or isolated from the rest of the animals.  Hopefully during this time the rest of the horses will get twice-daily temperature checks to ensure any other animals that may have been infected are detected and isolated as soon as possible.  Other routine infection control practices are hopefully also in place, such as hand hygiene between handling animals, and not sharing equipment between stalls and horses (particularly things like water/feed buckets, twitches, grooming supplies etc.).  These practices should be in place all the time, but they frequently get extra attention in outbreak situations.

The remarkable part about this case is what the stable owner did after the disease was diagnosed.  Instead of trying to keep it quiet or cover it up, she not only reported it to the Board of Health, but she also called everyone who visited the farm and the local veterinary hospitals, and even posted information on facebook to let everyone know what was going on.  Fantastic!  Part of the reason for being so proactive may be that the local horse expo last April was close to empty due to cases of EHV in the area affecteing 14 horses.  It is great to see someone reaching out like this to give the community a "heads up" so that others will keep a closer eye on their animals and hopefully prevent spread of the disease.  Hopefully she did it in an informative manner, and along with announcing the problem also told people about the plan to contain it.  It's always important to include the plan of action so the news itself doesn't incite panic.

Mad Cow in Alberta

Last week the Canadian Food Inspection Agency (CFIA) announced that a case of bovine spongiform encephalopathy (BSE), more commonly known as Mad Cow Disease, was found in an Alberta beef cow

BSE belongs to a group of diseases called transmissible spongiform encephalopathies (TSEs) that are not caused by bacteria, viruses, fungi or parasites, but rather by abnormally-shaped proteins call prions.  Prions are extremely difficult to destroy, and they can't be killed using antimicrobial drugs because they aren't actually microbes.  Exposure to the prions, most commonly through ingestion, can lead to spread of disease.  That's why Canada banned the use of most animal proteins (specifically from most other mammals) from use in cattle feed back in 1997, in order to decrease the risk of BSE spreading if it ever got into the Canadian cattle population.  In 2003 an enhanced feed ban was introduced after the first case of BSE was found in a Canadian cow.  The ban prohibits "specified risk materials" (SRM) from cattle from entering the human food chain AND from being used in animal feeds.  The SRM includes all the tissues where prions would most likely be found, such as the brain and spinal cord, in animals over 30 months of age.

Most TSEs seem to be relatively species specific, but there is still a lot we don't know about them.  Unfortunately, there is strong evidence that the prion that causes BSE can cause disease in people, called variant Creutzfeldt-Jacob disease (vCJD).  The "variant" differentiates this disease from sporadic or familial CJD, a rare human disease that has been recognized since the 1920s.  Just over 200 cases of vCJD have been diagnosed since it was first detected in 1996, most of which occurred in Great Britain.  There is currently no evidence that these prions can cause disease is dogs or horses, but they do appear to be the causative agent of a similar disease in cats (feline spongiform encephalopathy (FSE)).  Given that these prions have crossed at least two species barriers (people and cats), the possibility that they could affect other species as well cannot be dismissed.

What will be the impact of this single case in Alberta?  Hopefully not much.  The World Organization for Animal Health considers Canada a controlled BSE risk country, and one case won't change that status.  Canada has an extensive surveillance system through which more than 30 000 cattle are tested every year for BSE, and this is the first case detected in 4 years.  This case was in fact a good example of the surveillance system in action - the case was detected before any part of the cow (not just the SRM) was allowed to enter the food chain.  The Canadian food supply is still very safe, as is the animal food supply.  The worrisome part of this case is that the cow was born in Alberta in 2009, well after the enhanced feed ban was put in place.  So the question is, how did the cow get exposed to the prions?  Cases can rarely also occur sporadically in cattle (as for classical CJD in people), could this have been one of those?  The incubation period for BSE is typically years, so the investigation is focusing a lot on the farm of origin, not just the farm where the cow last resided. This is where the ability to trace animal movement and movement of animal products becomes so important, as they are in so many disease investigations.

Are we too clean?

A recent episode of the popular TVO current affairs show "The Agenda with Steve Paikin" explores the topic of “Our Relationship with Cleanliness" - an informative, yet fun look at the topic of germs. Panelists (including yours truly) take a cultural, historical, psychological and sociological look at the microorganisms on us and around us - and how we respond to them (including some points on contact with pets, of course!). Worth watching!


EEE in Ontario 2014

2014 was the worst year ever for Eastern Equine Encephalitis (EEE) in Ontario (though our numbers still pale in comparison to more endemic areas in the southern US, such as Florida). A recent article published in the Animal Health Lab (AHL) Newletter (December 2014) by Dr. Alison Moore from OMAFRA sums things up well:

"Twenty-two horses and 2 emus in the province died or were euthanized due to the disease with potentially as many deaths being suspected by attending veterinarians. Two horses were confirmed infected but survived. Counties in Eastern Ontario suffered the greatest casualties. Diagnosis in 21 horses was by serum IgM ELISA testing and 3 were diagnosed by RT-PCR on brain tissue. The affected horses were diagnosed between the end of July and the end of October. Ages of affected horses ranged from 2-20+ years, with no breed or sex predilection. Most of the infected horses were unvaccinated backyard horses and only a single horse per property was clinically affected. Most horses had an acute onset of disease with death or euthanasia performed within 24-48 hours. Common clinical signs included ataxia progressing to recumbency, with fever noted in some and blindness and head pressing noted in others. In the 2 horses that survived, the clinical signs were mild (ataxia and lethargy). The 2 emus were diagnosed with hemorrhagic enteritis and EEEV confirmed in the intestine and liver by RT-PCR.

The virus causing EEE is transmitted by mosquitoes. In Ontario, the most important species is Culiseta melanura, which feeds on birds. Bridge vectors, mosquitoes that feed on both birds and mammals, then complete the cycle to humans and horses. Outbreaks occur in hardwood, flooded areas with competent avian reservoirs and mammals present. Horses and humans are dead-end hosts as they do not produce sufficient viremia to infect mosquitoes.

So why was 2014 such a devastating year? Some speculate that eastern Ontario was relatively warmer this year than other parts of the province, others say it was due to the amount of spring precipitation. Others implicate the spring migration of wading birds such as herons from Florida. Herons are a preferred host for Culiseta sp. over winter in Florida, a major reservoir state for EEEV. The spring migration of herons and similar birds is thought to disseminate the virus to the northern USA and Canada. OMAFRA and Public Health Ontario will be working together over the winter to determine any associations between ecological and meteorological factors and disease occurrence."

Given the amount of activity we saw with this virus this past summer, vaccination of horses against EEE (particularly in hard-hit areas) will be important come spring to help avoid a repeat of this year's outbreak.

More information about the occurrence of EEE and other equine neurologic diseases in Ontario is available on the OMAFRA website: Equine Neurological Disease Surveillance 2014.

OAHN Podcast on Rabies for Ontario Veterinarians

The new Ontario Animal Health Network, developed as part of the OMAFRA-UofG partnership under the Disease Surveillance Plan (DSP), has produced a number of podcasts on important topics for veterinarians.  These podcasts are great for people on-the-go, as they can be downloaded and played anywhere on a portable device/phone, and they include discussions with experts from the Ontario Veterinary College, Animal Health Laboratory, OMAFRA and others.

The latest posting is a podcast on what Ontario veterinarians need to know about rabies.  This has been a hot topic since April 2014, when the Canadian Food Inspection Agency (CFIA) dramatically changed their long-time role in the national rabies response program.  There are two versions, including a full version and a slightly shorter version for small animal veterinarians (which simply leaves out some of the details for large animal cases).  Although the target audience is veterinarians, technicians and other veterinary staff may also find the information useful.

For more information about the Ontario Animal Health Network, visit the DSP homepage.  More information on rabies can be found on the Worms & Germs Resources - Pets page, and in our archives.


Lyme disease & ticks: New infosheet

The latest Worms & Germs infosheet, all about Lyme disease and ticks, is now available on the Resources - Pets page.  Although it's getting colder and occasionally snowy up in Ontario, there are lots of parts of North America where ticks are active all year round.  It's particularly important for any "snowbirds" who may travel south with their pets over the winter to be aware of the potential for exposure to ticks and the diseases they transmit (not just Lyme disease!), and to make sure their pets (as well as they themselves) are properly protected.  (The same goes for exposure to mosquitoes, which can transmit (among other things) heartworm.)

Remember that dogs (nor any other mammal for that matter) cannot transmit Borrelia burgorferi, the bacterium that causes Lyme disease, to people; however, this is a good example of a "one health" disease that clearly affects both people and animals.  Finding the disease in one species is an indication that the other is at risk as well, when there is exposure to a common source (i.e. the ticks).

Thanks to University of Guelph professor and parasitologist Dr. Andrew Perigrine for his input on the infosheet as well.

Image: A female blacklegged tick, Ixodes scapularis, engorged with a host blood meal. (Source: CDC Public Health Image Library 15993)

Never a simple story: West Nile in California

Orange County CA is currently experiencing a major outbreak of West Nile infection in people. Since January 94 cases have been confirmed, three of which were fatal, representing nearly a quarter of the 400 cases reported across the country so far this year. The number of cases of infection with a mosquito-borne virus like West Nile (or EEE, which we’ve been seeing over the last month in Ontario horses) can be affected by a lot of factors, including climate/weather, flooding or drought, bird populations and movements, mosquito populations and local mosquito species, and population density of those affected, be they people or animals.

Often we associated wet weather and flooding with increased incidence of diseases like West Nile, but this year California is experiencing a drought. How does that make sense? It’s been suggested that the dry weather is driving birds into more populated areas to look for water. More infected birds in the area provides more opportunity for mosquitoes to bite the birds and then transmit the virus to a person. The number of mosquito pools testing positive in Orange County (80%) is the highest its been since West Nile first hit California a decade ago, and 6.5 times more dead birds (260 total) have tested positive for WNV compared to 2013.

Most of the human cases in California included some signs of illness. When you consider that 80% of people infected with WNV show no signs of the disease, that means there has actually been an even larger number of people actually infected.

The impact on the local horse population has not been mentioned, but it is unlikely that horses will escape this outbreak unscathed. After a relatively slow year for WNV in 2013, I wonder how many horse owners in the area may have decided to forgo vaccinating their horses this year, and may now be regretting it. It’s easy for us to get complacent about infection control when things are going well. In the case of West Nile, people may stop taking precautions to avoid mosquitoes, to remove standing water from their property, and vaccinating their horses. It’s important to remain vigilant though, because there are so many different factors involved in the cycles of various diseases that predicting their resurgence can be extremely difficult, if not impossible. Taking some simple preventative steps, and making basic infection control practices habit can help reduce the impact of unexpected outbreaks, and help keep everyone (people and animals) healthier and safer.

Rabies myth-busters 101: Cats and bats

Rabies is a very serious disease.  We're very lucky in Canada that in most parts of the country the prevalence of this disease is now quite low, in large part due to wildlife control and vaccination efforts.  Unfortunately that also seems to make some people quite lax when it comes to (common sense) things like vaccinating their pets and avoiding direct contact with rabies vectors such as foxes, skunks, raccoons and bats.  Here are some of the most common misconceptions (or lapses in judgement) that we encounter.

1. My cat never goes outside, so it doesn't need to be vaccinated for rabies.

FALSE.  False false false.  It seems to be very difficult to get this message across to pet owners.  Your cat may live inside, but cats can escape.  Even my own cat, who has lived indoors his entire life for more than a decade, one day suddenly decided to explore the great outdoors.  Was I ever glad he was vaccinated at that point!  Even more importantly, bats - currently the most common rabies vector in most parts of Canada - can get into your house.  This happens even in the middle of large cities, and to people who live in apartments.  If your cat is unvaccinated and happens to have contact with a bat that gets in your house, kitty could be facing a 6-month quarantine which is not easy or fun for anyone.

2. My cat had all its shots when it was a kitten, so it's protected.

FALSE.  Cats (and dogs, and ferrets) need at least TWO rounds of rabies vaccination before they are considered fully protected.  Generally they get one dose at 3 months of age (with their last set of puppy/kitten shots) - 30 days later they are considered "primarily vaccinated".  The animal then needs a booster 1 year later (regardless of the type of vaccine used) at which point it is then considered fully vaccinated for 1 to 3 years, depending on which vaccine was used.  As soon as that 1 to 3 year window expires, kitty once again faces a 6-month quarantine if it is potentially exposed to rabies, which is just what happened to a dog in North Carolina recently.

3. If I have a bat in my house, I should get rid of it as soon as possible.

MAYBE. If you see a bat fly into your house through a door or a window, you can definitely try to shoo it back out as soon as possible as long as you don't touch it (lots of people use things like tennis rackets or brooms for this, but remember you don't need to hit the bat).  If you're not comfortable with that, trap the bat under a big bowl or bucket, or in a closed room with no animals or people, and call animal control (or a friendly neighbour) to help you with it.

BUT if the bat has touched any person or if there is a chance that your cat (or dog) may have touched the bat or been playing with it do not let the bat escape.  A risk assessment needs to be performed in these cases to determine if the amount of contact with the bat could have been enough to transmit rabies virus.  If the answer is no, the bat can then be released, but if the answer is yes, then it is very important to keep the bat so it can be tested for rabies.

Have your pets vaccinated for rabies by a veterinarian on a regular basis.  Make sure they are up-to-date and that you (or your veterinarian) have the records to show it.  It is by far the best insurance for preventing rabies in your pets, and avoiding unpleasant, long and difficult quarantine periods.  It is now summer in Canada and wildlife (including bats) are active - don't wait, get your pets updated today.


Equine Infectious Anemia: New info sheet

Although at times it may seem that winter is never-ending in parts of Canada, spring is actually only a couple of months away.  Along with spring comes insect season, and along with insects comes more than a few viruses.  One of these is the virus that causes equine infectious anemia (EIA).  This pathogen is a retrovirus like the human immunodeficiency virus (HIV), but EIA only affects equids (e.g. horses, donkeys, mules).  It's a very serious concern in the horse world, because horses become infected for life, and in Canada we have strict control measures to help prevent the spread of EIA into and within the country.  Nonetheless, in 2013 cases were detected on numerous premises in BC, Alberta and Saskatchewan.  Maps of the areas affected are available of the website of the Canadian Food Inspection Agency (CFIA).

To help horse owners understand more about this disease, the existing control program and the reasons behind it, as well as how they can help prevent the spread of EIA, we've created two new info sheets in collaboration with Equine Guelph and Equine Canada: a full-length version complete with references (9 pages) and a shorter summary version (4 pages).  Both versions are now freely available for download from the Worms & Germs Resources - Horses page, along with our many other equine infectious disease info sheets.

The Trouble With Gloves

When it comes to hand hygiene, there is an unfortunately all-too-common misconception that wearing gloves makes hand washing or using alcohol-based hand rub unnecessary. In veterinary and human medicine, gloves, like hand hygiene, are typically used for two reasons: to prevent spread of germs or chemicals from a patient/person/object/surface to a person’s hands, and/or to prevent the spread of germs or chemicals from a person’s hands to a patient/person/object/surface. However, gloves are not the infallible barrier to germs that many people would like to think they are. Here are a few reasons why:

  • Even new gloves can have holes in them: The accepted quality control limit for defects in medical gloves large enough to leak water is 1.5%. That may seem relatively low, but when you consider the hundreds of gloves that may be used over time in a veterinary (or human) clinic, that can add up to a lot of potential hand-to-patient or patient-to-hand pathogen transmission.
  • Gloves can be damaged during use: Glove tears or punctures during use can be extremely common, particularly for certain procedures involving anything pointy or sharp (e.g. equipment, teeth, claws) or long procedures.  Studies have shown that glove punctures that may occur during surgical procedures are frequently undetected by the person wearing the gloves. Even though gloves may provide an added layer of protection for a time, proper hand hygiene before and after glove use helps reduce the risk of transmission when that barrier breaks down.
  • Bacteria can multiply under gloves: Anyone who has ever had to wear any kind of rubber, latex or vinyl gloves for more than 5-10 minutes knows how sweaty and hot it can make your hands, so you can imagine the kind of sweaty soup that can accumulate when gloves need to be worn for even longer than this. That’s why hand hygiene before putting on gloves is so important for “clean” procedures like surgery, because it helps decrease the number of bacteria on the hands to start, and ultimately the amount that will grow back by the time the procedure is done. Hand hygiene after glove removal is important so the “soup” isn’t being spread to the next patient, person or object.
  • We use gloves for the highest-risk procedures: Glove use is typically recommended for the cleanest procedures (i.e. surgery) and the dirtiest procedures (i.e. things with a high “ick” factor, like handling feces). A glove puncture in surgery could potentially lead to contamination of sterile tissues, resulting in a surgical site infection. A glove puncture (or contamination of the hands when removing gloves) when handling high-risk material like feces can lead to transmission of fecal pathogens to anyone or anything that person may touch afterward (including themselves). In a sense, hand hygiene is actually even more important in situations when gloves are typically worn!

Although proper glove use and hand hygiene applies primarily to veterinary and healthcare workers, there are times when glove use is also recommended at home (e.g. caring for pets with certain kinds of infections, higher-risk individuals performing certain tasks like cleaning up pet messes). Remember that gloves are not a substitute for hand hygiene - always wash your hands or use hand rub after taking gloves off. It is also important not to touch anything with your gloved hands that will later be touched by someone without gloves, and be sure to put used disposable gloves directly in the garbage.

Older Entries

August 26, 2013 — Capnocytophaga Info Sheet

August 21, 2013 — Keeping kids safe around pets

August 8, 2013 — All about tapeworms and Echinococcus

July 4, 2013 — Mythbusters: Pandemics and new diseases

May 10, 2013 — Cat scratch disease info sheet

January 30, 2013 — Equine MRSA in Israel - Different strain, same old tricks

August 17, 2012 — Equine Infectious Anemia: Outbreak Out West

July 9, 2012 — "Human suicide parasite" in cats

January 18, 2012 — Murray Valley Encephalitis down-under - Help from the chickens

November 11, 2011 — equIDblog has moved to Worms & Germs!

October 28, 2011 — Study Seeking "Superbugs" In Horses

September 30, 2011 — Who's Better At Biosecurity?

August 17, 2011 — More Mosquito-Borne Mayhem

January 27, 2011 — Lions and tigers and glanders

September 24, 2010 — Lyme disease in Australia?

June 11, 2010 — Newborn killed by Husky

May 11, 2010 — Ringworm at the OSPCA

May 5, 2010 — World Hand Hygiene Day

March 1, 2010 — Risks of Raw - More evidence

January 13, 2010 — Baylisascaris in Winnipeg

November 26, 2009 — Things not to do for Thanksgiving

November 18, 2009 — Antibiotic Awareness Day

October 22, 2009 — Swine flu has gone to the birds

September 9, 2009 — Canine lepto: It's that time of year again

July 7, 2009 — Bug of the Month: Equine Infectious Anemia Virus

May 24, 2009 — Cooperating on Q Fever

May 15, 2009 — Oprah's Parvo Pups

May 9, 2009 — Rhodococcus equi in horses and people

May 7, 2009 — Garden veggies and poopy parasites

April 30, 2009 — Worms & Germs - Thanks to our readers!

April 28, 2009 — Swine flu: What about the pigs?

March 6, 2009 — More on Avian Influenza

February 5, 2009 — Testing for ringworm with toothbrushes

February 4, 2009 — Buyer Beware - Scrutinizing New Products

January 23, 2009 — Sleeping sickness - Don't doze off

January 21, 2009 — Smuggling Psittacosis

January 19, 2009 — Mumps - from people to dogs?

January 10, 2009 — Cat Scratch Disease - Bartonella henselae

January 3, 2009 — Echinococcus on the rise in Bashkiria, Russia

December 28, 2008 — Dog Bite Septicemia - Capnocytophaga canimorsus

December 16, 2008 — Cheyletiella - The walking dandruff

December 12, 2008 — Rabies Vaccination in Horses: Core Issues

December 2, 2008 — Neurological bunnies: Encephalitozoon cuniculi

November 24, 2008 — Leptospirosis and Pot-Bellied Pigs

November 10, 2008 — Hurray for Winter - Mother Nature's Infectious Disease Control

November 7, 2008 — Flu problems: people vs pets

November 5, 2008 — Cleaning up raccoon latrines

October 31, 2008 — Eastern Equine Encephalitis - Not Just For Horses

October 21, 2008 — Nontraditional Pets and Children: Beware

October 14, 2008 — Ringworm Part 2: Cleaning Up

October 12, 2008 — Ringworm: skin fungus by any other name

October 8, 2008 — More about Echinococcus tapeworms in dogs

September 30, 2008 — Updated: Speaking of Baylisascaris...

September 18, 2008 — Updated: Raccoon Roundworms - Baylisascaris procyonis

September 11, 2008 — Brucellosis in dogs

September 6, 2008 — Echinococcus and hydatid disease - not your average tapeworm

September 3, 2008 — Feline Immunodeficiency Virus - HIV/AIDS for Cats

August 6, 2008 — Q Fever - From goats to people (and pets!)

August 2, 2008 — Eastern Equine Encephalitis - Not just for horses

July 31, 2008 — Water Foul - Cryptosporidiosis

July 27, 2008 — Controversy over Crohn's and Cows

July 10, 2008 — Happy Household Hamsters

July 8, 2008 — Should all dogs in Ontario be vaccinated for leptospirosis?

June 26, 2008 — Cat bites - Why it's not "just a scratch"

June 16, 2008 — Tularemia Trouble

June 9, 2008 — Toxoplasmosis - Why Your Cat Shouldn't Get the Blame or the Boot

May 20, 2008 — Fido fights allergies

May 9, 2008 — Camping with canines - tick tick not!

May 6, 2008 — Horses and MRSA

May 2, 2008 — The Great Indoors - Keeping Kitty Content

April 16, 2008 — Not-so-likable licks

April 11, 2008 — Information Sheets for Pet Owners