Tapeworm

Tapeworm is a common name for several species of flatworms in the class Cestoda that inhabit the small intestine of vertebrates. Adult tapeworms are long, segmented worms composed of a scolex (head) with attachment organs and a chain of proglottids that produce eggs. They lack a true digestive system and absorb nutrients directly through their skin-like surface. Lengths vary from a few centimeters to meters.

Life cycle and transmission vary by species but share a general pattern. Eggs or gravid proglottids are shed in feces. Intermediate hosts ingest the eggs, where larvae form cysticerci in muscles or other tissues. Humans typically acquire infection by eating undercooked or raw meat containing cysticerci (definitive hosts in Taenia and Diphyllobothrium species) or, for some species, by ingesting eggs leading to tissue-stage infections such as cysticercosis or echinococcosis in organs.

Human tapeworms of medical importance include Taenia solium (pork), Taenia saginata (beef), Diphyllobothrium latum (fish), and Dipylidium caninum (dog tapeworm, occasionally infecting children). Echinococcus species cause hydatid disease in the liver or lungs and require different considerations. Many tapeworm infections are asymptomatic; when symptoms occur, they may include abdominal discomfort, weight loss, or nutritional deficiencies. Diagnosis is typically by stool examination for eggs or proglottids; imaging or serology is used for tissue-stage infections.

Treatment usually involves antiparasitic medications such as praziquantel or niclosamide; albendazole may be used for specific infections or cystic disease. Prevention focuses on thorough cooking of meat, proper food handling, hygiene, and sanitary measures to prevent fecal contamination and interrupt transmission. Public health efforts address animal reservoirs and food safety to reduce incidence.