Chagas disease — DTM&H MCQ
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Correct answer: D — Triatomine reduviid bug
The correct answer is D, Triatomine reduviid bug. Chagas disease (American trypanosomiasis) is caused by Trypanosoma cruzi and is transmitted when infective faeces from a nocturnally feeding triatomine (reduviid, "kissing") bug contaminate the bite wound, conjunctivae or mucous membranes, typically in poor rural housing with thatched roofs and mud walls across Latin America, including Bolivia. The clinical picture described (dysphagia from oesophageal dysmotility, right bundle branch block and apical left ventricular aneurysm) is the classic chronic cardiac and gastrointestinal presentation of Chagas disease, occurring years to decades after the initial infection. Right bundle branch block with apical aneurysm is a highly specific combination for chronic Chagasic cardiomyopathy and is a recognised exam discriminator. Confirmatory serology in the chronic phase, as given here, seals the diagnosis and therefore the vector. Why the other options are wrong: E. Ixodes tick: transmits Lyme disease, tick borne encephalitis and babesiosis, not trypanosomiasis; it has no role in T. cruzi transmission. A. Anopheles mosquito: is the vector for malaria (Plasmodium species) and some arboviruses, not for trypanosomes. C. Phlebotomine sandfly: transmits Leishmania species (and sandfly fever virus), producing cutaneous, mucocutaneous or visceral leishmaniasis, a different protozoan disease entirely. B. Glossina tsetse fly: transmits African trypanosomiasis (T. brucei gambiense/rhodesiense), which causes sleeping sickness in sub-Saharan Africa, not the Latin American cardiac/gastrointestinal disease described here. Key point: Right bundle branch block plus apical aneurysm in a patient from rural Latin America is the classic sign of chronic Chagas cardiomyopathy, transmitted by the triatomine reduviid bug.
Reference: GOV.UK, Chagas disease: migrant health guide, UK Health Security Agency, 2023 (https://www.gov.uk/guidance/chagas-disease-migrant-health-guide)