Anopheles malaria vector — DTM&H MCQ

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HardMalariaAnopheles malaria vectorDTM&H

A village health team in northern Uganda is investigating persistent malaria despite bednet distribution. Most mosquito biting occurs indoors between midnight and 04:00, and larvae are found in sunlit clean pools near houses. Which vector is most consistent with this pattern?

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Correct answer: E — Anopheles gambiae

Anopheles gambiae (E) is the correct vector. It is the principal African malaria vector, and its behaviour matches every clue in the stem: it is highly anthropophilic and endophagic, feeding indoors, with peak biting activity from after midnight until around 04:00, exactly when the village team recorded transmission despite bednets being up. Its larvae characteristically develop in small, temporary, clean, sunlit pools such as puddles, hoofprints, or brick pits rather than shaded, polluted, or fast flowing water, matching the described breeding sites. This combination of late-night indoor biting (which can occur after people have left protective nets, e.g. for toileting) plus preference for sunlit clean water breeding sites is the classic entomological signature of An. gambiae and explains persistent transmission despite bednet coverage. Why the other options are wrong: A. Aedes aegypti: this is a day biting mosquito (crepuscular peaks at dawn and dusk), breeds in artificial water containers around houses, and transmits arboviruses (dengue, yellow fever, chikungunya), not malaria. C. Culex pipiens: bites at dusk and night but favours polluted, organically rich water (drains, stagnant sewage) for larvae, and is principally a vector of filariasis and arboviruses such as West Nile virus, not malaria. B. Glossina morsitans: this is the tsetse fly, a day biting vector of African trypanosomiasis, with no aquatic larval stage at all since it deposits larvae directly onto soil. D. Phlebotomus papatasi: the sandfly vector of leishmaniasis, active at dusk and night but breeding in soil and organic debris, not water, and unrelated to malaria transmission. Key point: nocturnal (midnight to 04:00) indoor biting combined with larvae in clean sunlit temporary pools is the diagnostic ecological signature of Anopheles gambiae and malaria transmission.

Reference: University of Florida IFAS Extension, EENY601/IN1048: African Malaria Mosquito Anopheles gambiae Giles (Insecta: Diptera: Culicidae), citing Gillies and de Meillon 1968 on peak nocturnal biting activity (midnight to 04:00) and indoor feeding preference. https://entnemdept.ufl.edu/creatures/AQUATIC/anopheles_gambiae.htm