Aedes dengue vector — DTM&H MCQ

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HardEntomology and vector controlAedes dengue vectorDTM&H

A dengue control team investigates a city neighbourhood with many febrile cases after heavy rain. Larvae are found in discarded tyres, buckets and rooftop tanks around houses, and adults bite mainly during the day. Which vector is most likely?

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Correct answer: C — Aedes aegypti

The correct answer is C, Aedes aegypti, because it is a container-breeding mosquito that thrives in the artificial water collections described (tyres, buckets, rooftop tanks) and bites predominantly by day. Heavy rain filling discarded containers around houses creates exactly the peri-domestic breeding sites Aedes aegypti favours, and its diurnal biting pattern with peak activity around dawn and dusk fits the stem precisely. This species is the principal urban vector of dengue worldwide, and its close association with human dwellings (endophilic resting, container oviposition) explains explosive urban outbreaks following rainfall. NaTHNaC and UKHSA travel health guidance confirm that these mosquitoes breed in water containers including buckets, cisterns and tyres, and are most active during daylight hours. Why the other options are wrong: A. Anopheles funestus: this is a major African malaria vector that breeds in permanent, vegetated freshwater habitats such as swamps and rice fields, and it feeds predominantly at night (indoor, late-night biting), not day, and is not linked to dengue. B. Culex tritaeniorhynchus: this mosquito breeds in flooded rice paddies and transmits Japanese encephalitis; it is crepuscular/nocturnal in its biting behaviour, not a daytime feeder, and is unrelated to dengue transmission. E. Glossina palpalis: this is a riverine tsetse fly transmitting African trypanosomiasis, associated with vegetation along rivers and streams, not artificial containers, and it does not transmit dengue. D. Simulium damnosum: this blackfly breeds in fast-flowing, well-oxygenated rivers and transmits onchocerciasis; its larvae require turbulent water, not stagnant containers, ruling it out here. Key point: daytime-biting mosquitoes breeding in small artificial water containers around homes after rain point to Aedes aegypti and urban dengue transmission.

Reference: NaTHNaC (TravelHealthPro), Dengue factsheet: Aedes mosquitoes breed in water containers (buckets, cisterns, tyres) and are most active during daylight hours, 2024. https://travelhealthpro.org.uk/factsheet/13/dengue