cysticercus

Cysticercus is the larval form of Taenia tapeworms that develop in the tissues of an intermediate host. In Taenia solium and Taenia saginata, the larval stage exists as cysticerci in the muscle of the intermediate host—pigs for T. solium (cysticercus cellulosae) and cattle for T. saginata (cysticercus bovis).

Life cycle and infection: Humans are the definitive host for adult Taenia worms when they ingest cysticerci in undercooked pork or beef, leading to intestinal taeniasis. Humans can also become accidental intermediate hosts after ingesting Taenia eggs shed in the feces of a person with taeniasis, which can develop into cysticerci in various tissues, most notably the brain (neurocysticercosis).

Clinical features and diagnosis: Cysticerci in muscle are often asymptomatic; involvement of the brain, eyes, or spine can cause seizures, headaches, visual changes, or focal neurological deficits depending on location and parasite burden. Diagnosis relies on neuroimaging (CT or MRI) showing cystic lesions, frequently with a visible scolex, and is supported by serology. Stool examination can detect eggs or proglottids in intestinal infection.

Treatment and prevention: Cysticercosis is treated with antiparasitic drugs such as albendazole or praziquantel, usually with corticosteroids to control inflammation. Neurocysticercosis may require longer therapy and anticonvulsants. Taeniasis is treated similarly. Prevention emphasizes proper cooking of pork and beef, meat inspection, sanitation, and measures to prevent fecal-oral transmission in endemic areas.