Taeniasis (Tapeworm)

Also called cestodiasis and commonly called tapeworm, taeniasis is a parasitic infection that can result from several types of parasites. The incidence of tapeworm infestation varies with the type.

Tapeworm usually is a chronic but benign intestinal disease. However, infestation with Taenia solum may cause dangerous systemic and central nervous system (CNS) symptoms if larvae invade the brain and striated muscle of vital organs. Tapeworm seldom is fatal unless it isn't treated.

Causes

Taeniasis is caused by Taenia saginata (beef tapeworm), T.solium (pork tapeworm), Diphyllobothrium latum (fish tapeworm), or Hymenolepis nana (dwarf tapeworm).

T.saginata, T.solium, and D. latum are transmitted to humans by ingestion of uncooked or undercooked beef, pork, or fish (such as pike, trout, salmon, and turbot) that contains tapeworm cysts. Gastric acids break down these cysts in the stomach, freeing them to mature. The mature tapeworms then fasten to the intestinal wall and produce ova that pass from the body in stool.

H. nana is transmitted directly from person to person and requires no intermediate host. It completes its life cycle in the intestine. Inadequate hand washing facilitates its spread.

Symptoms

Tapeworm infestation does not usually cause any symptoms. Infection is generally recognized when the infected person passes segments of proglottids in the stool, especially if the segment is moving.

Diagnostic tests 

Observation of tapeworm ova or body segments in stool allows diagnosis of a tapeworm infestation. Because ova aren't excreted continuously, confirmation may require multiple specimens.

Treatment

Administration of praziquantel cures up to 95% of patients. In beef, pork, and fish tapeworm infestation, the patient receives the drug once; in severe dwarf tapeworm infestation, twice (5 to 7 days each, spaced 2 weeks apart).

After drug treatment, all types of tapeworm infestation require follow-up stool specimens during the next 3 to 5 weeks to check for remaining ova or worm segments. Persistent infestation requires a second course of medication.

Prevention

In the U.S., laws governing feeding practices and inspection of domestic food animals have largely eliminated the problem of tapeworm. Adequate cooking of meat destroys the tapeworm larvae and will prevent infection by tapeworm. Good hygiene and hand washing after using the toilet will prevent self-infection in a person already infected with tapeworms.