Room for wildlife and their worms?

Article by Dr. Emily Jenkins, veterinarian and Associate Professor, Veterinary Public Health, University of Saskatchewan

everystockphoto – foqus

Am I the worst thing that could happen to wildlife?  I am a veterinarian – sworn to protect animal health – and a researcher on diseases shared by animals and people. I constantly give animals a bad name by pointing out the diseases that they carry. I look at a fuzzy baby raccoon and think – “what worms are inside that one that could end up in my kid’s eye?” But if asked about the risks of urban wildlife, my sympathies are with the wildlife.  After all, we built in their backyard.

There are risks associated with wild animals in our cities.  In my hometown of Saskatoon, there are increasing reports of cougars in the river valley, moose on the main drag, and even coyotes on campus.  Apart from attacks and car accidents, some of these “invaders” harbor invisible dangers in the form of parasites.

One of these urban coyotes was shot for hanging around the sheep barn on our campus.  On autopsy, there were hundreds of thousands of tapeworms (Echinococcus multilocularis, or E. multilocularis), the heaviest infection we have seen. Up to a third of coyotes in western Canada probably harbor this tapeworm in their guts.  It’s harmless to them, but not to other hosts.

Known in Europe as the dangerous fox tapeworm, E. multilocularis causes parasitic tumours in the livers of its hosts, rapidly spreading to fill the entire body cavity.  We can tell when we have a case in mice because we find a pregnant male – so full of parasitic tumour that he can barely waddle.

Echinococcus multilocularis, distribution map in North America.

Recently my lab has found European-type strains of this tapeworm that are causing fatal disease in dogs in Canada.  This is surprising because dogs don’t normally get this stage of the parasite or show any signs of illness, suggesting that these new strains might be more pathogenic – and possibly more likely to cross into people.

In Europeans, about 20 new cases of E. multilocularis are detected every year and are difficult to treat, requiring life long drug therapy and radical surgery to remove the parasitic tumor.  Treatment of a single case is estimated to cost $100,000 to $300,000 in U.S dollars, a significant concern for public health departments with an eye on the bottom line.  If strains of this parasite have recently come over from Europe as unwelcome souvenirs of Fido’s family vacation, they could pose a new threat to pets and people.

So it’s my job as a veterinarian and a health researcher to let pet owners and other people know that urban coyotes are probably shedding eggs of this parasite into their green spaces.  Eggs that can survive for years.  Eggs that can survive almost every chemical disinfectant known to man.  Eggs that are immediately infective for their next unsuspecting host.  The best bet to get rid of the eggs is probably a flamethrower.

But Western Canadians don’t need any more ammunition against coyotes, already deeply unloved by farmers and ranchers. For that matter, they probably don’t need any encouragement to use flamethrowers.

So the message that I want to send to urban dwellers is this: Deworm your pets regularly. Don’t let them roam. Educate your kids about “look with your eyes, not your hands” (and make sure they wash their hands anyway, because my kids never listen to me).  Keep your garbage secured to avoid attracting wildlife.  Don’t feed the animals.  Whenever possible, get out and enjoy wildlife and wild places.

photo: wideurbanworld.blogspot.ca

The message that I want to send to urban planners in Western Canada is: Stop urban sprawl into wildlife habitat. New divisions are springing up in the middle of their home ranges. Cities in the prairies are among the fastest growing in Canada, and have some of the lowest population densities (for example, Saskatoon has 50 people/square km while Kitchener-Waterloo has 577 people/square km). Leave green corridors through cities for wildlife movements – but recognize that they might not make the best parks for pets and picnics.

Finally, I issue a challenge to conservationists and researchers: prove the benefits of wildlife in our cities. Show us that green ravines don’t just attract undesirables like teenagers, raccoons, and coyotes.  Show us that they create wildlife viewing opportunities for an urban population increasingly detached from nature. And maybe with better urban planning and a more balanced understanding of risk, we can keep wildlife in our cities – even with their worms.

Acknowledgements:

Karen Gesy, Jamie Rothenberger, Andrew Peregrine, Moira Kerr, Alessandro Massolo, Craig Stephen (for One Health vs wildlife conservation conversations) and the Banff Science Communication Course instructors and participants of 2013.

Photo courtesy – Hamilton Greenwood

For more information about living with urban wildlife, please visit http://www.mnr.gov.on.ca/en/Business/FW/2ColumnSubPage/STEL02_168419.html