Infection is most common in South America, Central America, India, Africa and parts of Asia, Europe and Mexico.
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Infection
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The eggs of the tapeworm or the gravid proglottids, the larval stage of the parasite, are passed in the human stool and infect vegetation. Eggs or larvae will remain viable for months in this state. A pig ingests the eggs or the larvae by eating the vegetation. The larvae migrate to the pig's intestines, then through the circulatory system and into the muscle of the animal.
Cysticerci
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Within the muscle, the larvae develop into cysticerci where they can live for many years. Humans contract the pig tapeworm by eating raw or undercooked pork. The cysticerci of the worm are ingested and attach themselves to the small intestines.
If the larvae infect humans rather than pigs at this stage, the condition in the human host is known as cysticercosis and can cause life-threatening illness.
Adult
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Once inside the human intestines, the tapeworm will reach maturity within five to 12 weeks. The worm will remain attached to the intestine where it will feed upon its host. The parasite may then live up to 25 years.
Reproduction
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The adult worm will produce proglottids. The proglottids mature into gravid proglottids and detach from the adult worm. They migrate to the anus and pass in the stool. The adult tapeworm may produce 1,000 proglottids. Each proglottid contains up to 50,000 eggs. These eggs attach to vegetation and the life cycle begins again.
Treatment
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Those infected with the pig tapeworm may notice the proglottids in their stool. Most often those infected will have no symptoms or, at worst, mild intestinal upset. However, in some cases, the infection---especially if it occurs in the cysticerci stage---can result in more serious complications such as cysts, blurred vision, blindness, headaches and seizures. The medication praziquantel is usually prescribed to kill the tapeworm and to end the life cycle.
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