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Diphyllobothriasis

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Illustrations

Antibodies
Antibodies

Alternative names    Return to top

Fish tapeworm infection

Definition    Return to top

Diphyllobothriasis is an infection caused by a fish tapeworm.

Causes, incidence, and risk factors    Return to top

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).

Symptoms    Return to top

The vast majority of infected individuals have no symptoms. Symptoms seen with heavy infections may include:

Signs and tests    Return to top

Treatment    Return to top

Niclosamide or praziquantel are given in a single dose to treat the tapeworm infection. Vitamin B-12 injections or supplements may be needed for the treatment of megaloblastic anemia.

Expectations (prognosis)    Return to top

Fish tapeworms can be eradicated with a single treatment dose. There are no lasting effects.

Complications    Return to top

Calling your health care provider    Return to top

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.

Prevention    Return to top

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

Update Date: 11/18/2003

Updated by: D. Scott Smith, MD, MSc, DTM&H, Infectious Diseases Division and Dept. of Microbiology and Immunology, Stanford University Medical School, Stanford, CA. Review provided by VeriMed Healthcare Network.

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