Echinococcosis

Echinococcosis is a disease caused by worms of the genus Echinococcus. Echinococcosis typically involves the larvae of the parasite growing in the liver, but they can also spread to other organs such as the spleen, lungs and brain.

Two forms of the disease have been reported in Canada:

• Cystic echinococcosis, caused by the parasite Echinococcus canadensis, also known as E. granulosus
• Alveolar echinococcosis, caused by the parasite Echinococcus multilocularis

Echinococcosis is a zoonotic disease, which means that animals can transmit it to humans. However, such cases are rare.

Several species of animals, both domesticated and wild, are affected by echinococcosis.

Foxes, wolves and coyotes are the wild animals most prone to having the two species of the adult parasite in their intestines and excreting the infectious eggs in their feces.

Rodents and cervids, such as deer, caribou and moose, can become infected by ingesting eggs found in their environment.

As far as domesticated animals are concerned, dogs and, less commonly, cats can be infected by both parasite species and develop the disease.

In recent years, the parasite E. multilocularis has spread to Ontario and Québec. Two areas with higher risk of infection have been identified in Montérégie and Bas‑Saint‑Laurent.

Wild canids usually show no signs of disease.

In dogs, cats, cervids and rodents, signs of the disease result from the growth of cysts ^{Read the content of the note 1} containing the larvae of the parasite, and thus generally take a long time to develop. Symptoms vary depending on what part of the body is affected.

Symptoms may include:

• Loss of appetite
• Nausea
• Vomiting
• Abdominal pain
• Fatigue
• Weight loss
• General malaise
• Jaundice
• Swelling of the belly
• Abnormal fluid accumulation in the belly

Echinococcosis is spread through the ingestion of parasite eggs or larvae in prey or the environment, such as vegetation, water or soil. Animals infected with the parasite can contaminate the environment with their feces, regardless of whether they exhibit signs of the disease.

The eggs of the parasite are highly resistant and can survive for up to one year. Eggs can be transported by wind, water or insects.

Wild animals

The eggs of the parasite are most commonly shed in the feces of wild canids.

Small rodents and other herbivores such as cervids serve as intermediate hosts. They become infected by ingesting eggs on contaminated vegetation. The parasite’s life cycle is complete once wild canids are infected by consuming larvae of the parasite in their prey.

Domesticated animals

Dogs and cats are particularly vulnerable to infection if they eat infected wildlife, raw game meat or raw offal and may shed the eggs of the parasite in their feces.

Humans

Humans can be infected through contact with surfaces contaminated with the feces of an infected animal, such as by:

• Eating improperly washed vegetables or berries or drinking untreated water
• Touching their mouth with hands that have been contaminated from playing in a sandbox, picking berries, hunting and trapping, farming, gathering firewood, gardening, etc.
• Touching their mouth with hands that have been contaminated by contact with an animal, animal hair or fur, or a harness, pillow or other item that has been in contact with an infected animal

Echinococcosis is typically treated with antiparasitic therapy.

At a more advanced stage of disease, surgery may be necessary to remove part of the cyst-affected organ. Without treatment, echinococcosis can be fatal.

Several measures can help prevent echinococcosis in animals:

• Never feed your pet raw game meat or offal.  
• Do not let your pet roam. Avoid contact with wildlife and wild animal feces and carcasses.
• Keep your pet from hunting and eating wild animals, such as small rodents.
• If your pet goes outside, have your veterinarian check them for parasite eggs and worms at least once a year.
• Consider deworming your pet once a month. Talk to your veterinarian for more information.

Human cases of echinococcosis are very rare. Only a few cases have been reported in Québec to date.

Alveolar echinococcosis is generally the most serious form of the disease. Alveolar echinococcosis often begins with a cyst in the liver, but these cysts tend to aggressively infiltrate organs, and larval metastases can spread to other organs such as the spleen, lungs and brain. Cystic echinococcosis creates a lesion that is more often located in the liver or lungs, but can also spread to the spleen, kidneys, heart, bones and brain.

Symptoms of the disease usually appear 5 to 15 years after infection.

Symptoms vary depending on cyst location, but may include:

• Loss of appetite
• Nausea
• Vomiting
• Stomach or chest pain
• Fatigue
• Weight loss
• Coughing
• General malaise

Infection can also cause:

• Jaundice
• Swelling of the belly
• Abnormal fluid accumulation in the belly
• Without treatment, echinococcosis can be fatal.
• Echinococcosis does not spread through person-to-person contact.

There are many steps you can take to protect yourself from echinococcosis. Here are some tips:

• Wash your hands with soap and water after coming into contact with an animal and before eating, preparing food or touching your mouth with your hands.
• Put up a fence around your property or vegetable garden to keep out wildlife. Visit the Deterrents  page to learn more.
• Keep away from wild animals such as foxes, wolves and coyotes. Avoid contact with wildlife feces.
• Pick up pet feces promptly, using gloves or two plastic bags for protection, and wash your hands afterwards.
• Thoroughly wash fruits, vegetables, mushrooms or other foods that have been foraged from forests before eating or cooking with them.
• Cover children’s sandboxes when not in use.
• If you are a hunter, follow the recommendations for wild game meat.