Ecoregional and altitudinal distribution of the principal malaria vectors in Colombia

In Colombia, with over 100,000 cases reported in 2023, malaria is a significant vector-borne disease. The wide range of climates and highly variable topography and land cover of the country support a high species richness, favouring different scenarios of transmission. This study characterizes the ecoregional and altitudinal distribution of the principal malaria vectors in Colombia, Anopheles albimanus, Anopheles darlingi, Anopheles nuneztovari sensu stricto (s.s.), Anopheles neivai sensu lato (s.l.) and Anopheles calderoni, and represent their historic and current distribution.

A database of the distribution of the principal malaria vectors in Colombia was constructed using information from diverse sources dating 1929 to 2023. Elevation and ecoregion were obtained using the U.S. Geological Service (USGS) and the Ecoregions2017^©Resolve shapefile, respectively. Distribution maps of the principal malaria vectors regarding elevation and ecoregion were generated.

A total of 2,371 records of the main malaria vectors were obtained. This study shows that the principal anopheline species are widely distributed. In the coastal regions of the country, An. albimanus (Atlantic and Pacific regions) and An. neivai s.l. (Pacific region) are highly represented. However, records of these species are also associated with inland areas. Anopheles darlingi, An. nuneztovari s.s. and An. calderoni are mainly inland species. Besides its wide distribution, An. darlingi presents a high association with forests. Anopheles nuneztovari s.s. is mainly associated with the Middle Magdalena Valley, Urabá-Bajo Cauca, Atrato River, and Catatumbo, and An. calderoni is found far inland, especially in the Cauca River Valley. Regarding altitude, these malaria vectors are predominantly distributed below 500 m a.s.l. Nevertheless, An. albimanus and An. calderoni are also present at elevations over 1,000 m a.s.l. Notably, An. albimanus and An. neivai s.l. are the two species that suggest elevation increase through time.

The distribution of the principal malaria vectors in Colombia, encompasses both coastal and inland areas, and a variety of ecoregions, particularly the Chocó-Darién and Magdalena-Urabá moist forests. The comprehensive identification of ecoregions and elevations in which malaria vectors have historically been and are currently distributed will contribute to determining receptivity areas for designing malaria stratification plans and the prioritization of zones for its prevention and control.