THE FOX TAPEWORM
AN EMERGING HEALTH THREAT FOR CANADIANS
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Fox Tapeworm Echinococcus multilocularis, next to a paperclip (photo by Brent Wagner).
Keeping ourselves and our pets safe by changing our lifestyle
What is the Fox Tapeworm?
Echinococcus multilocularis is a tiny creature (3-6mm long) inhabiting the intestines of infected canines like coyotes and foxes, and existing as a relatively harmless lodger. If
however, a dog owner becomes infected via activity with an infected dog or the
handling of infected scat, the parasite sets up shop in the human intestine but
soon moves on to other internal organs. While still considered rare, people
with low immunity are at greater risk and the number of people infected is
rising. Four people in Alberta have been diagnosed with Echinococcus
multilocularis in the last four years. Before that, the only previous case
in Canada happened in Manitoba in 1928 along with a case in Minnesota
U.S., in 1976.
How did it come to Canada?
Research has confirmed that the latest wave of this tapeworm comes from Europe. How it got here is not certain. Along with Alberta this version of the parasite has been found in Ontario wildlife and has likely been present in the region for decades.
In European wildlife it’s only found in the intestines of foxes. In the less virulent North American strain it occurs in the intestines of both foxes and coyotes.
How did it enter Ontario?
Current theory is that the parasite may have come in from Michigan, and may also have come in with those dogs imported from central parts of Europe, especially Switzerland. There are currently no rules for screening or deworming protocols in place for imported dogs.
How is it transmitted?
Humans can be exposed in two ways: By eating foods grown at ground level such as carrots that have been exposed to infected canine feces, or when exposed to microscopic traces of infected dog feces in pet fur; if the dog hunts rodents – if that dog is petted and then the person touches their mouth or food, the parasite’s eggs are ingested. Fox tapeworm eggs can survive months to years in the environment. Dogs pick up the lethal form of this disease by eating coyote, fox or wolf scat (eventually colonies will migrate to the liver and other organs). Dog get the intestinal version when they eat infected rodents (harmless to a dog but dangerous for us).
How to protect yourself and your dog
• Break the habit of allowing your dog to lick the plates
• Never allow your dog to lick your face or mouth. Enforce the same rule with the kids
• Always wear gloves when gardening
• Always wash fresh produce from either the garden or the store, thoroughly. Experts list E. multilocularis as one of the top three food-transmitted parasites, worldwide
• Wash your hands after handling dogs, especially dogs you don’t know. Wash the good old fashioned way, hot soap and running water. Hand sanitizers are ineffective against most parasites
• Think about alternate sleeping arrangements for your dog instead of in your bed
• Wash your hands after scooping up poop
• Wash your hands before you eat
• Avoid dog parks where dog, fox, coyote and rodent feces abound. E. multilocularis has recently been detected in Calgary dog parks
• Have your dog wormed on a regular basis (this is a conversation we should all be having with our vet) and be sure the worming medication is specifically formulated for the prevention of this kind of tapeworm. This is crucial for dogs that are free roaming on property with access to rodents, coyotes, foxes and their feces.
Is there a cure?
Dogs: The intestinal strain can be eradicated by a proper worming with the right kind of medication. The liver version is deadly. Even with surgery and treatment the survival rate is low and probably unaffordable for most of us since the dog would have to remain on anti-parasitic medication for the rest of its life.
Humans: The parasite soon shows up as lumps on the liver – Humans exposed to the parasite should get treatment immediately. The problem is that the parasite grows slowly, and usually does not cause symptoms right away. Left untreated, it spreads to other parts of the body. If treated when it’s localized a surgeon can remove the whole infected area while prescribing several months of post-operative anti-parasitic drugs.
If Echinococcus multilocularis has spread too far in the liver or moved to other internal organs the infected person would need to remain on anti-parasitic drugs for the rest of their life. Only about a third of patients are alerted to the problem by pain and in two thirds of cases, by the time it’s found, surgery is no longer an option. A mass in the liver is identified through an ultrasound or CT scan. If left untreated, the parasite will kill its human host in 10 to 15 years.
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