Tapeworm infection is acquired by eating raw or undercooked meat of infected animals. Beef generally carryTaenia saginata while pigs carryTaenia solium. The larvae from the infected meat develop in the human intestine into the adult tapeworm -- which can grow to longer than 12 feet.

Tapeworms are segmented, with each segment (proglottid) capable of producing eggs. Eggs are dispersed by individual or groups of proglottids detaching and passing out with the stool. The groups of proglottids from the beef tapeworm are capable of movement and actively crawl out through the anus.

Adults and children with tapeworm (T. solium, pork tapeworm only) can, if appropriate hygiene is lacking, become self-infected by ingesting eggs from their tapeworm which were picked up on their hands while wiping or scratching the anus.

Additionally, these individuals can expose other individuals to T. solium eggs, usually via food handling. Ingested eggs hatch in the intestinal track and the larvae migrate through the tissues, where they encyst. If larvae migrate to the brain, they can cause seizures and other neurological problems. This condition is called cysticercosis.

Certain freshwater fish and salmon may also carry a tapeworm called Diphyllobothrium latum (see diphyllobothriasis ).

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.

• stool examined for ova (eggs) of Taenia solium or Taenia saginata
• segments of worm, "proglottids," may also be visible in stool
  • Taenia saginata proglottids may move around visibly

Tapeworms are treated with oral medications, usually in a single dose. The drug of choice for tapeworm infections is niclosamide. Praziquantel and albendazole can also be used.

Complete eradication of the tapeworm occurs following treatment.

• self-infection with tapeworm eggs -- cysticercosis (T. solium only), which may cause seizures
• rarely, worms may cause obstruction of the intestine

Call for an appointment with your health care provider if you pass something in your stool that looks like a white worm.

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.