Trichuris dysentery syndrome — DTM&H MCQ

Correct answer: E — Albendazole or mebendazole

The correct answer is E, Albendazole or mebendazole. The vignette describes trichuriasis (Trichuris trichiura, whipworm): barrel-shaped eggs with bipolar plugs are the classic diagnostic finding on stool microscopy, and heavy paediatric infection classically produces chronic bloody diarrhoea, growth faltering (failure to thrive) and rectal prolapse due to the worm's attachment along the distal colon and rectal mucosa. Benzimidazole anthelmintics (albendazole or mebendazole) are the first-line treatment for Trichuris trichiura, acting by inhibiting microtubule formation in the parasite and disrupting glucose uptake, leading to worm death and expulsion. Heavy or persistent infections, as implied by rectal prolapse here, often require a longer course (for example mebendazole 100mg twice daily for three days) rather than a single dose, reflecting lower single-dose cure rates for whipworm compared with other soil-transmitted helminths. Why the other options are wrong: D. Ivermectin single dose: Ivermectin has poor efficacy against Trichuris trichiura as monotherapy and is the treatment of choice for strongyloidiasis and scabies, not whipworm. B. Fluconazole: This is an antifungal with no activity against helminths; it is irrelevant to a parasitic nematode infection. A. Praziquantel: This targets trematodes and cestodes (schistosomiasis, tapeworms), not nematodes such as Trichuris, so it has no role here. C. Metronidazole: This treats protozoal infections (amoebiasis, giardiasis) and anaerobic bacteria; it has no activity against whipworm and would not address the egg morphology described. Key point: Barrel-shaped eggs with bipolar plugs plus rectal prolapse in a child point to heavy Trichuris trichiura burden, treated with a benzimidazole (albendazole or mebendazole), not antiprotozoals or drugs active against trematodes.

Reference: BNF (NICE), Mebendazole and Albendazole monographs, Anthelmintics section, medicines.org.uk/BNF, accessed via NICE-endorsed British National Formulary; see also Manson's Tropical Diseases, Trichuriasis chapter, for clinical correlation of rectal prolapse with heavy Trichuris trichiura infection.