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Poop, parasites and public health

It may look like ordinary, everyday dog poop, but to researchers at the Western College of Veterinary Medicine (WCVM), those little lumps contain a treasure trove of public health information.

That's one of the key facts that I learned last  summer as a WCVM research student, travelling around Saskatchewan collecting dog feces — a job that gave me first-hand experience in veterinary public health.

I worked with Dr. Emily Jenkins and her PhD student, Janna Schurer, in the WCVM's Zoonotic Parasite Research Unit. Schurer is surveying populations of dogs in northern and Indigenous communities to determine the prevalence of parasites and the risk of transmission between dogs and people.

Schurer chose to focus on these communities because of three factors: they lack regular access to veterinary services, they have large free-roaming dog populations and many of their residents rely on harvested wildlife (country foods). Her study's preliminary results show that parasite prevalence levels in the communities' dogs are up to 20 times higher than those in dogs living in areas with easily accessible veterinary service — such as Saskatoon.

"Dogs are particularly interesting because they bridge the gap between veterinary and public health," says Schurer, adding that the species has potential as a sentinel surveillance system for human disease.

Jenkins and Schurer are especially interested in Echinococcus tapeworms that have been found in wild and domestic animals in Canada. When people accidentally ingest eggs from the environment (passed by an infected carnivore), they can develop into cysts in the lungs and liver — or in less common places such as the brain — sometimes with tragic consequences.

Echinococcus infection was once a relatively common occurrence in the North when sled dogs were used for transportation, but the incidence has significantly decreased. While infection with this parasite is now a rare phenomenon, surveillance, prevention and education will help to keep the risk low for people.

As well, recent cases in dogs in Canada have raised concerns that introduced strains of E. multilocularis may pose new threats to animal and human health.

Since Echinococcus eggs are a health hazard in people, the standard protocol in endemic areas of the world is to freeze fecal samples from carnivores at a temperature of -80 C for three days. This temperature renders the eggs non-viable and eliminates the risk of human infection.

But not all areas of the world have Echinococcus — opening the debate on the accuracy of detecting other parasite species that have lower tolerance to extreme cold. Parasite egg counts could be significantly decreased in frozen samples if the eggs are damaged beyond recognition.

Part of my summer project explored the effects of freezing protocols on parasite egg counts in fecal samples from horses and dogs. I found that hookworm and trichostrongyle roundworm eggs change their appearance significantly — and some are not recognizable. This means that fecal flotations may be underestimating egg counts of some parasites if samples are frozen before processing.

However, our work showed that parasite prevalence was relatively unaffected by freezing which is good news for our surveys.

In addition to trolling the microscope for parasite eggs, I travelled with Schurer and Jenkins to remote and Indigenous communities in Saskatchewan where we collaborated with community organizations including the Canine Action Project and Team North.

Key objectives of these initiatives are to develop and implement humane and sustainable animal population control. Another goal is to increase basic veterinary services by organizing preventive health clinics that include vaccination, deworming and surgical sterilization. We worked in co-operation with the communities on the planning and funding of these events.

To help increase community awareness of veterinary services and to enhance the educational component of these community-based clinics, we created posters about parasites and prevention in their pets that can be posted in schools and public meeting areas.

These clinics gave me the chance to hone my skills in physical examinations, surgical preparation and monitoring, and surgical skills. I also collected blood samples from more than 100 dogs that were tested for exposure to vector-borne diseases such as heartworm and Lyme disease. Fortunately, we didn't detect these diseases in these dog populations.

Our group was also involved in the University of Saskatchewan's SCI-FI VetMed summer day camps at the WCVM. I helped out in labs where the campers ran fecal flotation tests and examined the results for eggs. They also had the chance to explore many other weird and wonderful parasites. I couldn't believe how excited the campers were to play with poop!

My summer research job highlighted the integral role of veterinarians in public health. It gave me a new appreciation for the creepy, crawly creatures we can't see with the naked eye, and it taught me many valuable veterinary skills. I plan to remain involved in public health and animal welfare projects, and I'm excited to continue exploring the career options in veterinary medicine.

Funding for my research project was provided by Zoetis Canada and Idexx Laboratories.

Laura Davenport of Saskatoon, Sask., is a second-year veterinary student who participated in the WCVM's Undergraduate Summer Research and Leadership program in 2013. Laura thanks the entire Zoonotic Parasite Research Unit for "taking me under your wing and giving me such a great summer experience."
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