An infection caused by a fish tapeworm.

Alternative Names

Fish tapeworm infection

Causes, incidence, and risk factors

The fish tapeworm, scientifically named Diphyllobothrium latum , represents one of the giant tapeworm species. Humans become infected when they eat raw or undercooked fish that contain tape worm larvae (sparganum). The infection is seen in many areas where humans consume uncooked or undercooked fish from rivers or lakes. Diphyllobothriasis is seen in Eastern Europe, North and South America, African countries in which freshwater fish are eaten, and in some Asian countries. After a person has eaten of infected fish, the larva begin to grow in the intestine. The adult worm, which is segmented, may attain a length of 30 feet. Eggs are formed in each segment (proglottid) of the worm and are passed in the stool. Occasionally, a string of proglottids may be passed in the stool. Fish tapeworm infection may lead to Vitamin B12 deficiency and the subsequent development of megaloblastic anemia ( pernicious anemia ).

Signs and tests

Treatment

Niclosamide or praziquantel are given in a single dose to treat the tapeworm infection. Vitamin B12 injections or supplements may be needed for the treatment of megaloblastic anemia .

Expectations (prognosis)

Eradication of fish tapeworms can be accomplished with one treatment and no lasting effects.

Complications

Calling your health care provider

Call your health care provider if you have noticed a worm or segments of a worm in the stool. Also call if any family members have symptoms suggestive of pernicious anemia ( megaloblastic anemia ).

Prevention

Avoiding raw freshwater fish and cooking fish sufficiently will prevent infection with the fish tapeworm.