By Connor Lynch
GUELPH — Livestock farmers, especially sheep farmers who rely on dogs to protect their flocks, had better get into the habit of washing their hands if they haven’t already.
A type of tapeworm potentially fatal to humans has been found in 25 per cent of retrieved fox and coyote carcasses in Ontario, wrote professor Andrew Peregrine of the Ontario Veterinary College, along with several other researchers, in a study published earlier this year. The detention of the tapeworm was found mostly in Western Ontario.
Called the fox tapeworm, it’s found in wild canids such as foxes and coyotes and first appeared on the Ontario researchers’ radar back in 2012, even though the tapeworm had been detected in 13 northern U.S. states and three provinces — Manitoba, Saskatchewan and Alberta. Five Ontario dogs got sick with liver failure and eventually died. The tapeworm was to blame.
The tapeworm doesn’t bother the foxes and coyotes it infects. But when it infects mice, it gets into their livers, eventually killing them. When a dog eats an infected mouse, it can ingest the tapeworm eggs and suffer the same fate. If a dog ingests the eggs directly, the tapeworm isn’t harmful. A person, however, who ingests the eggs can suffer severe liver damage.
Symptoms in people don’t usually appear for five to 15 years, and by the time symptoms appear, the liver is usually already heavily damaged, Peregrine said.
The takeaway for farmers concerned about their health is to wash their hands after touching their working dog or after a coyote hunt. A dog, and certainly a wild animal, that is infected or has interacted with the droppings of an infected animal, will almost certainly have eggs on its coat, Peregrine said.
Peregrine was aware of only two cases of human infection. So there are greater odds of being struck by lightning. Said Peregrine: “That’s not a lot of people, but it’s awful if you’re one of them. It’s a risk, and so it still makes sense to wash your hands before eating or drinking.”
If your dog comes into the house normally and you think it could have picked up eggs, don’t let it inside. Or wash it first. The eggs can survive for up to a year in a moist environment, and your dog could be shedding them anywhere he goes. The eggs are also resistant to household cleaners, according to the Ontario Ministry of Health and Long-term Care.
Don’t plan on spotting eggs. The tapeworm itself, fully grown, is only about 1 cm long. The weather isn’t your friend in this either: the eggs will survive temperatures up to 80 C and as cold as — 80 C.
There are drugs available, said Peregrine, that can kill the worm. But it has to be caught before symptoms appear, and a course of treatment to prevent liver infection can last years. The same drug is used in both dogs and humans, although it’s a strong medication and not all dogs can handle it; at least one has died as a result of treatment, Peregine said.
Better data on the worm should be available soon, he said.