Common Molecular Detection of the Neglected Human Malaria Parasite Among Febrile Patients in Southern Regions in Senegal

Abstract

Background: In sub-Saharan Africa, Plasmodium falciparum is unequivocally responsible for almost all malaria cases and deaths. However, the long-neglected human P. vivax, P. ovale, and P. malariae parasites also emerge as relevant, though their prevalence and contribution to the burden of the disease are very poorly appreciated. This study aimed to bridge this gap and surveyed the circulation of non-falciparum malaria parasites among febrile patients in four regions in south Senegal. Methods: Blood samples were obtained from 1990 febrile patients during the malaria transmission seasons of 2020, 2021, and 2022 in four southern regions in Senegal (Kedougou, Kolda, Tambacounda, and Ziguinchor). Genomic DNA was isolated and tested for Plasmodium infections by using a combination of Plasmodium genus-specific qPCR and Plasmodium species-specific nested PCR. Frequencies and distribution of Plasmodium species according to region, period, and patient demographics were analyzed using R. Spatial patterns of infection were further explored and visualized with QGIS software version 3.30.2. Results: The Plasmodium positivity rate was 73.43% of which 67.92% were unique Plasmodium species infections and 32.08% were co-infections by two or three Plasmodium species. The results described the ongoing circulation of all non-falciparum species in three of the four study regions, the non-detection of P. vivax and P. malariae parasites among the samples tested in Ziguinchor, the first evidence of non-falciparum infections in Kolda and Tambacounda, as well as the first report of P. ovale in Ziguinchor. Conclusions: Our data call on clinicians to account for these species in clinical prognoses, but also on the National Malaria Control Programme to consider these species in their policy of reducing the incidence of the disease with a view to eliminating malaria in Senegal.