Muscle tapeworm cysts embedded in muscle tissue.

Section of caribou muscle containing muscle tapeworm cysts.

What causes muscle tapeworm cysts?

This condition is caused by the larvae of the tapeworm Taenia krabbei.

Lifecycle:  The tapeworm needs two hosts: a carnivore (eg. wolf or dog) and a (eg. caribou). The tapeworm grows and lays eggs in the intestines of the carnivore.  Eggs come out in the carnivore’s droppings and contaminate plants that are eaten by the herbivore.  The eggs hatch into larvae that travel in the blood to other parts of the herbivores body where they form cysts in the muscle.  Carnivores become infected when they eat meat with cysts.
 

Where do muscle tapeworm cysts occur?

The adult tapeworm occurs in wolves, lynx, bears and dogs without causing any harm.

The larval stage occurs in barren-ground and woodland caribou, and moose.

In the NWT and Nunavut, Taenia krabbei occurs commonly in caribou and occasionally in moose.
 

What are the signs of muscle tapeworm cysts?

Animals will probably appear healthy.

In the herbivore host, cysts are whitish or yellowish-white, round, and about 5 mm in diameter.

Cysts generally occur in both muscle and the heart but may also occur in unusual sites.

Surrounding tissues are usually normal.
 

How can I protect myself?

You cannot be infected by the cysts of T. krabbei.

Cysts can be easily removed during butchering.
 

Can I eat the meat?

Meat from infected animals is suitable for human consumption.

Cooking will kill the parasite.

Dogs can be infected with tapeworms if they eat the liver cysts.

Do not feed infected parts to dogs.
 

Samples to collect

portions of muscle containing cysts