# Beyond Anopheles gambiae sensu lato: exploring the impact of non-dominant Anopheles species on malaria persistence in high-transmission endemic areas of Burkina Faso

## TL;DR

This study explores how non-dominant Anopheles species contribute to malaria transmission in Burkina Faso, suggesting current control measures may be insufficient.

## Contribution

The study identifies and quantifies the role of secondary Anopheles species in malaria transmission in high-transmission areas.

## Key findings

- Anopheles nili and Anopheles coustani were found to be significant contributors to malaria transmission.
- Most mosquitoes were collected outdoors and showed strong preference for human blood.
- Plasmodium falciparum was detected in all secondary species except Anopheles funestus.

## Abstract

Despite widespread implementation of malaria control measures, including insecticide-treated nets (ITNs), indoor residual spraying (IRS), and seasonal malaria chemoprevention (SMC), malaria remains a major public health concern in Burkina Faso. The persistence of transmission is often attributed to increasing insecticide resistance in Anopheles gambiae sensu lato and drug resistance in Plasmodium spp. However, additional factors, such as climatic variability, ecological change, and shifts in vector species composition, may also play a role. This study investigated the geographic distribution of secondary malaria vectors and assessed their potential role in sustaining transmission at the national scale.

Between 2023 and 2024, mosquito surveys were conducted across the three main ecological zones of Burkina Faso using human landing catches (HLC) and pyrethroid spray catches (PSC). Secondary vector species were identified morphologically. Molecular assays were used to detect Plasmodium infections and characterize blood-meal origins. Climatic data from national meteorological stations were analyzed to explore associations between environmental variables and species abundance.

A total of 1718 Anopheles mosquitoes (excluding An. gambiae s.l.) were collected, 688 in 2023 and 1030 in 2024. Five species were identified: Anopheles nili, An. coustani, An. pharoensis, An. funestus, and An. rufipes. Most specimens originated from the Sudan zone, with An. nili overwhelmingly dominant (87.5% of captures in 2023; 93% in 2024). Rainfall and, to a lesser extent, temperature were significantly associated with species abundance at several sites. Most mosquitoes were collected outdoors and showed strong anthropophilic tendencies. Molecular screening detected Plasmodium falciparum in all species except An. funestus. Infection was highest in Diébougou, with sporadic positive samples in An. coustani and An. nili across both years.

Secondary vectors, particularly An. nili and An. coustani, appear to play an increasingly important role in malaria transmission in Burkina Faso. Their outdoor and sometimes opportunistic feeding behaviors highlight limitations of current indoor-focused interventions. These findings underscore the need to broaden surveillance and adapt vector control strategies to include secondary vector species in high-transmission settings.

The online version contains supplementary material available at 10.1186/s13071-025-07210-2.