Understudied Anophelines Contribute to Malaria Transmission in a Low-Transmission Setting in the Choma District, Southern Province, Zambia

The Southern and Central Africa International Center of Excellence for Malaria Research

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4 Scopus citations

Abstract

Malaria transmission has declined substantially in Southern Province, Zambia, which is considered a low-transmission setting. The Zambian government introduced a reactive test-and-treat strategy to identify active zones of transmission and treat parasitemic residents. This study was conducted in the Choma District, Southern Province, Zambia, concurrently with an evaluation of this strategy to identify vectors responsible for sustaining transmission, and to identify entomological, spatial, and ecological risk factors associated with increased densities of mosquitoes. Anophelines were collected with CDC light traps indoors and near animal pens in index cases and neighboring households. Outdoor collections captured significantly more anophelines than indoor traps, and 10 different anopheline species were identified. Four species (Anopheles arabiensis, An. rufipes, An. squamosus, and An. coustani) were positive for Plasmodium falciparum circumsporozoite protein by ELISA, and 61% of these 26 anophelines were captured outdoors. Blood meal assays confirm plasticity in An. arabiensis foraging, feeding both on humans and animals, whereas An. rufipes, An. squamosus, and An. coustani were largely zoophilic and exophilic. Linear regression of count data for indoor traps revealed that households with at least one parasitemic resident by polymerase chain reaction testing was associated with higher female anopheline counts. This suggests that targeting households with parasitemic individuals for vector interventions may reduce indoor anopheline populations. However, many vectors species responsible for transmission may not be affected by indoor interventions because they are primarily exophilic and forage opportunistically. These data underscore the necessity for further evaluation of vector surveillance and control tools that are effective outdoors, in conjunction with current indoor-based interventions.

Original languageEnglish (US)
Pages (from-to)1406-1413
Number of pages8
JournalAmerican Journal of Tropical Medicine and Hygiene
Volume106
Issue number5
DOIs
StatePublished - May 2022

Bibliographical note

Funding Information:
Financial support: This work was supported in part by funding from the National Institutes of Health International Centers of Excellence for Malaria Research (U19AI089680), Bloomberg Philanthropies, and the Johns Hopkins Malaria Research Institute (JHMRI), and a JHMRI pre-doctoral fellowship to M. E. G.

Publisher Copyright:
Copyright © 2022 by The American Society of Tropical Medicine and Hygiene.

PubMed: MeSH publication types

  • Journal Article

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