Anopheles species associated with malaria transmission in gold-mining areas of northwest Colombia.

Abstract

Background: In Colombia, mining is one of the main economic activities in four eco-epidemiological areas that contributes approximately 80% of annual malaria cases. Mining activity generates changes in the environment and creates newly available breeding sites to be colonized by malaria vector mosquitoes, which increases the risk of malaria transmission. The study aimed to identify the presence of Anopheles species and their role in malaria transmission in five malaria-endemic localities with gold mining extraction in El Bagre, Antioquia, Colombia.

Methods: A cross-sectional study was conducted in five localities of El Bagre, Antioquia where adult mosquitoes were collected indoors and outdoors. The taxonomic status of the Anopheles species was confirmed through COI sequencing. All mosquitoes were tested by ELISA to establish infection with Plasmodium spp., and infections were confirmed using nested PCR. Larval habitats were characterized to evaluate the association between Anopheles larval abundance and physical and biological parameters.

Results: Eleven Anopheles species were identified. Six specimens were positive for PCR Plasmodium test: Anopheles darlingi infected with Plasmodium falciparum, Anopheles nuneztovari s.s., and Anopheles punctimacula infected with Plasmodium vivax. The entomological inoculation rate (EIR) varied across localities ranging from 1.5 to 6.6 infective bites/person/month. The Anopheles species were collected from natural and artificial man-made excavations for gold mining, nevertheless, the physical and biological parameters examined did not show a significant association with their abundance in either type of larval habitat.

Conclusions: The results confirm the role of An. darlingi, An. nuneztovari s.s. and An. punctimacula as malaria vectors. The presence of their immature stages in gold mining excavations identified these habitats as potential breeding sites for Anopheles species in El Bagre. In these areas, implementing larval source management might be recommended as a supplementary measure for LLINs and IRS in the malaria vector program.