In late November, a dog in the Peterborough area was diagnosed with Echinococcus multilocularis (EM), a parasitic tapeworm that can lead to illness in dogs and, more rarely, humans. The region’s Sherbrooke Heights Animal Hospital said it’s the first time a case has been reported in the area, but five dogs in Ontario have been diagnosed since the first case was found in 2012.
It’s important to understand that EM can cause two types of illnesses: one being an intestinal infection that generally shows no symptoms, and the other, a serious condition that causes liver damage, says Andrew Peregrine, a professor at the Ontario Veterinary College and a board-certified specialist in veterinary parasitology.
“Whilst the intestinal infection doesn’t make [dogs] sick, it’s the public health concern that’s the issue,” he says, since there is a risk of transmission to humans. No human cases have been reported in Ontario to date, but some have been found in parts of Europe and Alaska.
Dogs can contract EM by eating an infected rodent, or consuming the feces of foxes or coyotes—common hosts to this parasite—that contain the eggs. “To try and put it in perspective, if your dog’s not running around eating rodents, this really isn’t a concern for you,” says Peregrine. However, he stresses the importance of talking to your vet about your dog’s risk level, which includes: being frequently off-leash (when it’s challenging to monitor behaviour), prone to eating rodents, or if they often roll around in an area with other animal feces present.
Owners can ask their veterinarian for a monthly tapeworm treatment as a precaution, but Peregrine says that should be used carefully, as dogs can develop resistance to it with overuse.
Where you live is also a factor. Peregrine has studied risk areas for EM by testing the fecal matter of wild canids (such as foxes and coyotes) in southern Ontario; of 460 samples, about 23 per cent tested positive for EM. The highest levels were around the northern shore of Lake Erie and the western end of Lake Ontario. While Peregrine doesn’t have data on the Peterborough region specifically, he said he’d put it anywhere from five to about 15 per cent.
Peregrine says that owners can also request their dog be tested specifically for the parasite, up to a few times per year; if a case is found, the vet is required to report it to the local public health unit. “Whether it’s liver or an intestinal case, they will do a risk assessment of that family to see whether there’s likely been exposure and whether any testing should be done,” he says.
EM can transmit to humans via exposure to infected feces from a dog, rodents, or other hosts, as well as from unwashed fruits or vegetables that may have been contaminated. This can lead to liver damage that is slow-acting and doesn’t show symptoms for about five to 15 years, but it can be serious and fatal. Ontario’s public health department made the parasite reportable in 2018 and is monitoring cases because of the possible risk.
As Peregrine explains, the best way to prevent transmission is rigorous hand-washing after contact with pets, wild animals, or the outdoors in general, and always washing fruits and vegetables, especially from a home garden.
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