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Alaska Department of Fish and Game


Parasites and Diseases
Muscle Tapeworm Cysts

A Field Guide
TO COMMON WILDLIFE DISEASES
AND PARASITES IN ALASKA

MUSCLE TAPEWORM CYSTS

caption follows
Moose meat with small Taenia krabbei cysts.

What causes muscle tapeworm cysts?
  • This condition is caused by the larvae of the tapeworm Taenia krabbei or Taenia arctos.
  • Lifecycle: The tapeworm needs two hosts: a carnivore (e.g., wolf or dog) and an herbivore (e.g., caribou). The adult 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 herbivore’s 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 as cysts most commonly in caribou and moose.

What are the signs of muscle tapeworm cysts?
  • Animals will usually appear healthy.
  • In the herbivore host, cysts are an oblong, semi-clear, fluid-filled sac with a white spot ‘head’ at one end.
  • 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? [can infect dogs]  [cook well]
  • Meat from infected animals, even when dried and uncooked, is suitable for human consumption.
  • Cooking will kill the parasite.
  • Dogs can be infected with tapeworms if they eat the muscle cysts.
  • Do not feed infected parts to dogs.

Samples to collect
  • Portions of muscle containing cysts
  • To report an occurrence or to submit a sample for identification/analysis, contact the DWC Wildlife Disease Surveillance reporting hotline 907-328-8354, send an email to dfg.dwc.vet@alaska.gov or visit your local ADF&G office.
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