Several news articles have been written lately about the recently-described cases of Echinococcus multilocularis infection in four people in Alberta. The cases of alveolar echinococcosis have occurred over the past 4 years, and raise significant concerns.
Echinococcus multilocularis is a small tapeworm but it causes big problems.
- It’s a potentially nasty parasitic disease that can act a lot like a tumour.
- By the time it’s recognized, treatment can be difficult.
- Since the incubation period is 5-15 years, infections identified now developed many years ago, and there are probably other people who are infected and don’t yet know it.
- This number of cases, combined with evidence of the parasite in wild canids (foxes, wolves, coyotes) in a couple of regions in southern Canada suggest the parasite is well established in certain parts of the country (besides the arctic) and probably beyond.
Eradication of this parasite isn’t practical in regions where it’s established, since it’s presumably well entrenched in the wildlife population. Its life cycle includes infection of small mammals (mainly rodents), that develop tumour-like lesions in their internal organs (typically liver). When the animal is eaten by a canid, the tapeworm develops in the intestinal tract, where it produces eggs. These eggs are shed in feces and the life cycle continues when another small critter ingests an egg. People can also develop the tumour-like lesions if they inadvertently ingest tapeworm eggs. Dogs can occasionally be infected in this manner too, but more often develop the intestinal infection after eating an infected rodent, and then shed eggs (which then poses a risk to people and other animals).
Here are a couple resources for more information:
Public Health Ontario’s 5 things to know about E. multilocularis
For veterinarians, the Ontario Animal Health Network (OAHN) infographic Emerging Risk: Echinococcus multilocularis in Ontario