Seroprevalence of SARS-CoV-2 in rural communities of Burkina faso (West Africa) assessed through blood-fed mosquitoes

Since the emergence of the COVID-19 pandemic, several surveillance measures have been implemented in African cities, including the continuous collection and analysis of epidemiological data to identify suspected or confirmed cases. Rural regions, where over half of Africa’s population resides, often face a scarcity of quality health care infrastructure and diagnostic services, hindering effective disease surveillance and potentially accelerating disease transmission. Our study aimed to assess COVID-19 seroprevalence and spread in rural Burkina Faso using an innovative noninvasive sampling method based on naturally blood-feeding mosquitoes as a proxy for human sampling. This cross-sectional study was conducted from October to November 2021 in eleven rural localities located along the RN1 road in Burkina Faso, including six villages near Bobo-Dioulasso (Bereba, Bombi, Dimikuy, Intiedougou, Koumbia, and Nahirindon) and five villages near Ouagadougou (Ouezindougou, Saria, Sissene, Tampelga, and Tathyou). Samples consisted of 690 blood-fed mosquitoes collected by aspiration from 299 human dwellings. The predominant vector species were Anopheles funestus and Anopheles gambiae. ELISA tests were performed to detect human anti-spike protein and anti-RBD domain antibodies to SARS-CoV-2. Overall, SARS-CoV-2 seroprevalence detected in mosquitoes was 31.16% (215/690). Seroprevalence was higher in rural areas near Bobo-Dioulasso, reaching 35.14% (130/370), compared with 26.56% (85/320) in areas near Ouagadougou. In addition to providing evidence of SARS-CoV-2 circulation during an active phase of the pandemic, this study evaluated the feasibility of using naturally fed mosquitoes as a complementary surveillance tool for monitoring SARS-CoV-2 seroprevalence in rural Burkina Faso. However, due to missing data on the time each mosquito took the blood meal, its source, and the proportion of mosquitoes feeding on the same individual hosts, this information serves as a crude minimum infection rate in these populations and additional sampling, and assays are needed to accurately extend these results to determine exact seroprevalence in these communities.