Chagas disease — DTM&H MCQ

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HardOther protozoal infectionsChagas diseaseDTM&H

A 49-year-old Bolivian man has exertional syncope and a dilated cardiomyopathy with right bundle branch block. He remembers reduviid bugs in the walls of his childhood home. What is the vector of the infection most likely responsible?

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Correct answer: A — Triatomine bug

The correct answer is A, Triatomine bug. This man has chronic Chagas disease from Trypanosoma cruzi, acquired via triatomine (reduviid) bug faeces contaminating a bite wound or mucous membrane, classically from bugs living in the mud or thatch walls of rural Latin American housing. Decades after the initial infection, chronic Chagas cardiomyopathy develops, typically presenting with dilated cardiomyopathy, conduction disease (right bundle branch block with or without left anterior hemiblock is the classic early ECG finding), apical aneurysm and a tendency to sudden death or exertional syncope from arrhythmia. The Bolivian origin, childhood exposure to reduviid bugs in house walls, and this specific cardiac phenotype together are pathognomonic for Chagas disease, so the vector sought is the triatomine bug. Why the other options are wrong: E. Tsetse fly: transmits African trypanosomiasis (Trypanosoma brucei), causing sleeping sickness with meningoencephalitis, not chronic dilated cardiomyopathy, and is confined to sub-Saharan Africa, not Bolivia. D. Sandfly: transmits Leishmania species causing cutaneous, mucocutaneous or visceral leishmaniasis, not cardiomyopathy. C. Blackfly: transmits Onchocerca volvulus causing onchocerciasis with skin and eye disease, unrelated to cardiac conduction disease. B. Anopheles mosquito: transmits malaria, which causes acute febrile illness and haemolysis, not a chronic dilated cardiomyopathy with RBBB decades after exposure. Key point: chronic exertional syncope with dilated cardiomyopathy and RBBB in someone from rural Latin America with a reduviid bug exposure history points to Chagas disease transmitted by the triatomine bug.

Reference: GOV.UK / UKHSA, Chagas disease: migrant health guide, 2023, https://www.gov.uk/guidance/chagas-disease-migrant-health-guide