Tapeworms

Abstract

Three major species of giant tapeworms, with mean lengths of 10–30 feet, may be found in the small intestines of man. The great size of these parasitic organisms has rendered them obvious since ancient times. All three tapeworms are transmitted by the ingestion of raw or undercooked flesh. Taenia saginata larvae are found in beef, those of Taenia solium in pork, and those of Diphyllobothrium latum in fish. The beef and fish tapeworms are distributed worldwide, with some transmission in the United States; the pork tapeworm is less widespread and is essentially an imported infection in the United States. Although these enormous intestinal helminths have been associated with abdominal and systemic disturbances, there is little definitive evidence for such symptomatology. Thus, the beef tapeworm appears to be essentially a benign, commensal organism. The larval stages of the pork tapeworm, however, can develop in man and spread throughout the body, including the brain; the lesions induced by these organisms are a major cause of epilepsy in some endemic areas. The fish tapeworm has a unique avidity for vitamin B₁₂ and has been associated with the development of pernicious anemia in man. Recent drugs have rendered the treatment of the adult intestinal tapeworms a relatively sure and simple process.