Taeniasis — DTM&H MCQ

Correct answer: B — Taenia saginata taeniasis

The correct answer is B, Taenia saginata taeniasis. The vignette describes motile, whitish proglottids passed in stool after eating undercooked beef, the classic presentation of adult beef tapeworm infection: gravid proglottids actively migrate through the anus and are noticed as moving segments, distinct from the passive egg or worm shedding of other helminths. Beef is the key epidemiological link, since cattle are the intermediate host harbouring cysticerci that develop into adult tapeworms in the human gut after ingestion of undercooked meat. Absence of neurological symptoms is reassuring and fits T. saginata rather than T. solium, since T. saginata does not cause human cysticercosis, unlike T. solium whose eggs can invade tissue including the CNS. Mild abdominal discomfort with visible motile segments and no systemic or neurological features is textbook uncomplicated intestinal taeniasis. Why the other options are wrong: D. Hymenolepiasis: caused by Hymenolepis nana, transmitted faecal-orally or via contaminated food, unrelated to beef, and does not produce visible motile segments since this small tapeworm sheds eggs, not proglottids. A. Ascariasis: caused by the roundworm Ascaris lumbricoides, acquired from soil-contaminated food or water, presenting with passage of adult roundworms (not flat motile segments) and sometimes pulmonary migration, unrelated to beef. E. Enterobiasis: caused by the pinworm Enterobius vermicularis, transmitted faecal-orally (not via beef), classically causing nocturnal perianal itching from egg-laying females, not motile proglottids. C. Diphyllobothriasis: caused by Diphyllobothrium latum, acquired from raw or undercooked freshwater fish, not beef, and can additionally cause vitamin B12 deficiency and megaloblastic anaemia, not described here. Key point: Motile proglottids after undercooked beef point to Taenia saginata; the crucial discriminator from T. solium is the absence of cysticercosis risk, since T. saginata does not cause neurological disease.

Reference: CDC Clinical Overview of Taeniasis (2024), Human Tapeworm (Taeniasis), https://www.cdc.gov/taeniasis/hcp/clinical-overview/index.html