Juxtaposition of Overnight and Early Evening Indoor-Trapped Anophelines in Nchelenge District, Northern Zambia
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Date
2022-05-04
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Johns Hopkins University
Abstract
Malaria, a parasitic disease of great public health importance and vectored by female mosquitoes of the Anopheles genus causes immense morbidity and mortality in many regions across the world, particularly in sub-Saharan Africa. Afrotropical mosquitoes are complex and vary in abundance over time and place, warranting further investigation into their prevalence and behaviors in regions experiencing high malaria burden despite active implementation of disease prevention measures. This study, taking place in Nchelenge, northern Zambia evaluates the morphological and molecular species identification, relative abundance, blood meal source, and infectious parasite prevalence associated with foraging vectors captured in traps placed within twenty-four participating study households overnight. Specimens collected overnight between the hours of 22:00 and 06:00 compared to early evening collections from 16:00 to 22:00 may provide greater insight into the complex relationship between vectors and human hosts, elucidating better mechanisms to interrupt vector-to-human contact provided that current measures primarily aim to mitigate overnight biting, leaving individuals less protected in early evening hours.
Results revealed an abundance of mosquitoes were collected during both early evening and late-night hours, consisting of the primary vector species in the region, Anopheles funestus along with the African malaria mosquito, An. gambiae, and additional understudied anophelines. Most mosquitoes were captured in traps placed within households located inland in contrast to those located lakeside. Host DNA from humans as well as animals including pigs, goats, and dogs were ingested by mosquitoes appearing to be engorged with a blood meal. Mosquitoes harboring infectious Plasmodium parasites were collected indoors during both early evening and overnight collections, highlighting the need to re-evaluate the dogma of malaria transmission occurring exclusively late at night. The results from these molecular analyses of vector composition and foraging behaviors, in conjunction with survey-based epidemiological data including household structural integrity, animal ownership, vector control intervention coverage, and study participant information allow for a better understanding of the continual burden of malaria in the region. This comparison of early evening versus overnight foraging mosquitoes reveals the need for additional surveillance and refined vector control and disease prevention measures in Nchelenge to reduce malaria transmission and improve public health.
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Keywords
malaria, anopheles, mosquitoes, vector-borne disease