Echinococcus multilocularis is a very tiny (<5mm) tapeworm that lives in the intestines of coyotes and foxes but also occasionally in dogs and cats. Although well established in Europe and parts of Asia, it was once thought that this tapeworm was rare in North America. However, recent studies in populations of coyotes and foxes in Alberta indicate that the number of infected animals is actually quite high (around 25%). Some of these studies were conducted at off leash dog parks in Calgary. As coyote and fox populations have moved into urban areas, dogs and cats are having more and more contact with potential sources of infection.
Foxes and coyotes (as well as dogs and cats) can contract this parasite through ingestion of infected rodents. When predators ingest a rodent infected with Echinococcus larva, the larva transforms to an adult in the intestines and starts to produce eggs within 2 months. The eggs are shed in feces into the environment. The eggs are then ingested when rodents eat contaminated vegetation and the life cycle continues. The eggs are very hardy in the environment and can last for months or even years. They can withstand great temperature swings and are not killed by most disinfectants.
Humans can come into contact with this parasite through contaminated feces. Exposure to microscopic particles of feces on pet fur is one potential source of infection. Another source is eating fruits or vegetables that are contaminated with dog, cat or wildlife feces. While often benign in wildlife populations, Echinococcus infections in humans can invade the liver and spread through the body like a tumor. This disease can be fatal in humans if not diagnosed and treated early. This tapeworm has recently emerged in Alberta, causing four different cases of human infection in 4 years. Before this time, the only case of Echinococcus in humans was in Manitoba in 1928. If dogs ingest feces infected with Echinococcus, the tapeworm could behave in a similar way and spread through the body.
It is important to prevent Echinococcus infection in our pets to avoid any potential illness as well as to reduce the transmission to humans. Keeping cats indoors and dogs away from areas frequented by wildlife can go a long way in preventing infection. Any dogs and cats that live an at-risk lifestyle should be dewormed regularly with a product that acts against Echinococcus tapeworms. It is worth noting that most routine flea, tick and heartworm dewormers are not effective against Echinococcus. Please discuss your pet’s lifestyle with one of our veterinarians or technicians. Together we can formulate a deworming schedule for your pet to reduce any potential infection risk.