Echinococcus Multilocularis Infection Fact Sheet

What is Echinococcus multilocularis?

• A parasitic infection caused by ingesting eggs of the Echinococcus multilocularis tapeworm.
• Once the eggs are inside the body, they develop into a larval form which grows as multiple masses (cysts) within the body.
• Once cysts begin to form in the body, the person develops a serious disease called alveolar echinococcosis.
• Cysts usually begin in the liver and develop into solid tumor-like masses. The parasite can later spread and cause growths in other organs like the spleen, lungs, and brain.

How is it spread?

• Eggs are passed in the stool of foxes, coyotes, wolves, dogs, or cats that have eaten infected rodents.
• Humans can ingest the eggs after eating or encountering things that are contaminated with the stool of these animals.
• Eggs can also be present on the fur of animals if the fur is soiled with stool.

When do symptoms start?

• Symptoms usually start five to fifteen years after someone has become infected.

What are the symptoms?

• During the early stages (five to fifteen years) there are usually no symptoms.
• If symptoms do occur, they may include tiredness, weight loss, abdominal discomfort, and weakness.
• In the later stages, symptoms may mimic those of liver cancer or cirrhosis and include abdominal swelling, malnutrition, yellowing of the skin or eyes (jaundice), and mental confusion.
• If left untreated, alveolar echinococcosis can lead to death.

How long is it contagious?

• In the environment, eggs of the parasite remain infective for approximately one year in lower temperatures and when in a wet environment.
• Humans cannot spread the parasite to other humans.

How is it treated?

• All individuals with the infection will need treatment.
• Treatment often involves a combination of surgery and chemotherapy.

How is it prevented?

• Anyone who handles wild dogs, or their carcasses, should wear plastic gloves and complete hand hygiene after glove removal.
• Wash all wild-picked fruits and vegetables carefully before cooking or eating.
• All dogs and cats that have access to wild rodents should be dewormed monthly.
• Pet owners should try to avoid allowing cats and dogs to eat wild rodents.
• Regular and frequent hand washing after handling pets and their stool, and before handling food.
• Areas where infected dogs/cats frequently visit should be cleaned and disinfected well and often (e.g. pet beds, floors, carpets, and car interiors).

Where can I get more information about Echinococcus multilocularis?

Contact the Communicable Disease Control (CDC) Program at 705-474-1400, or toll-free at 1-800-563-2808, ext. 5229 or email us at cdc@healthunit.ca.

References:

• Ministry of Health. (2022). Infectious Diseases Protocol, Appendix 1: Echinococcus multilocularis infection. 
• Ministry of Health (2025). Management of Echinococcus Multilocularis Infections in Animals Guideline. 
• World Health Organization (WHO). (2021). Echinococcosis. 
• Centers for Disease Control and Prevention. (2020). Parasites - Echinococcosis.

Created: Feb. 2026, by CDC