The role of Anopheles arabiensis and Anopheles funestus in malaria transmission within houses with different characteristics in South-eastern Tanzania

BackgroundMalaria vectors persist predominantly in houses lacking screened windows, doors, and eave space, leading to ongoing transmission. Some other vectors adapt their feeding behavior to sustain reproduction. This study evaluates the role of primary malaria vectors on malaria transmission in relation to house characteristics in Kilombero Valley. MethodsMosquito data collection was done using three methods: a CDC light trap, a miniaturized double net trap (DN-Mini trap), and a Prokopack aspirator through 222 households that were randomly selected in the three villages, namely Ebuyu, Chirombora, and Mzelezi. The houses are characterized during mosquito collections, and the Geographical Position System (GPS) was used to geolocate the sampled houses. Morphological identification was done on the collected sample (i.e., fed, part-fed, gravid, and unfed), and a sub-sample was sent to the laboratory to assess the sibling species, blood meal, and sporozoite. ResultsA total of 1542 Anopheline mosquitoes were collected, of which 79.1% (n= 1219) were An. funestus and 20.3% (n= 313) were An. arabiensis as primary malaria vectors, while the secondary malaria vector was 0.6% (n = 10). Out of 487 anopheline mosquitoes assayed for plasmodium falciparum sporozoite, 92.8% (n = 13) of An. funestus was reported to be dominant while An. arabiensis was dominant by 7.2% (n = 1). While An. funestus was the only species that had a blood meal and was found to feed on humans (88.16%, n = 134), dogs (11.18% n = 17), and a mixture of both human and chicken blood meal. In addition to that, the house with screened eave space had fewer An. funestus compared to the house with open eave space (RR = 0.978, p =0.864), while the house with a brick wall had a higher An. funestus compared with the house with a mud wall (RR = 0.690, p =0.107). ConclusionAnopheles funestus remained the dominant malaria vector responsible for all transmissions in the villages. The human population is at risk due to their preference for An. funestus, which contributes about 92.8% of infections in the village. Additionally, the house design appears to play a significant role in facilitating malaria vectors to continue transmitting malaria.