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Anopheles dirus

Southeast Asian forest malaria mosquito
Vector Risk: High
Genus: Anopheles

Anopheles dirus is the dominant malaria vector in the forests of Southeast Asia, and it is strongly associated with the forest ecosystem — rarely venturing into open or urban landscapes. This forest-edge habitat means malaria in Thailand, Laos, Cambodia, and Myanmar is effectively a frontier disease.

It bites in the early evening, often outdoors near forest margins and in forest villages. This outdoor-biting behaviour limits the effectiveness of indoor residual spraying compared to Anopheles gambiae in Africa. Trekkers, forest workers, and people living at forest edges are the primary at-risk groups.

The species is also notable for high rates of drug resistance in the parasites it carries — the Thai-Myanmar border has been the origin of multiple multidrug-resistant Plasmodium falciparum strains over the decades.

Biting behaviour

Early evening outdoor biter, active around sundown at forest margins. Will bite indoors but prefers outdoors. Feeds primarily on humans in forest villages.

Habitat

Shaded forest pools, stream margins, and gem-mining pits in hilly forested terrain. Strongly tied to intact forest — declines sharply in deforested areas.

Diseases transmitted

Malaria

How to identify

Dark-coloured mosquito with unmarked wingsAnopheles 45-degree resting postureFound almost exclusively in forest environmentsBites in early evening outdoorsRare in open plains, agricultural land, or cities

Where found

Forests of Thailand, Myanmar, Laos, Cambodia, Vietnam, and parts of southern China.

Precautions

CDC recommends antimalarial chemoprophylaxis for forest travel in endemic zones
WHO recommends insecticide-treated bed nets in forest accommodation
CDC advises long-sleeved clothing from dusk onwards at forest margins
WHO recommends permethrin-treated clothing for forest trekkers
CDC notes that outdoor-biting behaviour limits the effectiveness of indoor-only protection
WHO emphasises that forest-goers face higher risk than urban or agricultural-plain travellers

Recommended Protection

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WHO — Malaria in the Greater MekongCDC — Anopheles Mosquitoes

Countries where Anopheles dirus is relevant

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Vector information is sourced from WHO, CDC, and ECDC. Not medical advice. Personal decisions on repellents, vaccinations, or medication belong with a qualified travel health professional.

Anopheles dirus (Southeast Asian forest malaria mosquito) — Mosquito Species Profile | Mozzwise