Taenia solium (pork tapeworm) infection and cysticercosis

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Taenia solium infection (taeniasis) is an intestinal infection with adult tapeworms that follows ingestion of contaminated pork. Cysticercosis is infection with larvae of T. solium, which develops after ingestion of ova excreted in human feces. Adult worms may cause mild gastrointestinal symptoms or passage of a motile segment in the stool. Cysticercosis is usually asymptomatic unless larvae invade the central nervous system, resulting in neurocysticercosis, which can cause seizures and various other neurologic signs. Neurocysticercosis may be recognized on brain imaging studies. Fewer than half of patients with neurocysticercosis have adult T. solium in their intestines and thus eggs or proglottids in their stool. Adult worms can be eradicated with praziquantel . Treatment of symptomatic neurocysticercosis is complicated; it includes corticosteroids, antiseizure drugs, and, in some situations, albendazole or praziquantel . Surgery may be required.
Presentation, diagnosis, and management of intestinal infection with the adult T. solium tapeworm are similar to those of T. saginata (beef tapeworm) infection. Adult T. solium range in size from 2 to 8 meters.
However, humans may also act as intermediate hosts for T. solium larvae if they ingest T. solium eggs from human excreta (see Figure: Taenia solium life cycle). Some experts postulate that if an adult tapeworm is present in the intestine, gravid proglottids (tapeworm segments) may be passed retrograde from the intestine to the stomach, where oncospheres (immature form of the parasite enclosed in an embryonic envelope) may hatch and migrate to subcutaneous tissue, muscle, viscera, and the central nervous system.
Adult tapeworms may reside in the small bowel for years. They reach 2 to 7 m in length and produce up to 1000 proglottids; each contains about 50,000 eggs.
Taeniasis and cysticercosis occur worldwide. Cysticercosis is prevalent, and neurocysticercosis is a major cause of seizure disorders in Latin America. Cysticercosis is rare in Muslim countries. Infection in the US is most common among immigrants, but North Americans who have not traveled abroad have been infected by ingesting ova from immigrants harboring adult T. solium.
Rarely, zoonotic Taenia species other than T. solium cause neurocysticercosis.