Plasmodium falciparum Malaria and Arbovirus Co-Exposure in the Boende Health Zone, Northwestern Democratic Republic of the Congo.

Background: Malaria remains hyperendemic in the Democratic Republic of the Congo, while arboviral infections are increasingly reported but remain under-surveilled, particularly in remote regions. Overlapping ecological niches and non-specific clinical presentations complicate case management and surveillance. Methods: A cross-sectional door-to-door survey was conducted in December 2023 in Inkanamongo village (Lokolia Health Area, Boende Health Zone, Tshuapa Province). Blood samples were collected from 379 adults; malaria infection was assessed by using HRP2-based rapid diagnostic tests, and arboviral IgG antibodies were measured on dried blood spots using Luminex® multiplex immunoassay. Sociodemographic data were collected via standardized questionnaires. Results: Malaria prevalence was 51.7% (95%CI: 46.7-56.7). Overall arboviral seroprevalence reached 78.4% (95%CI: 73.1-81.5), dominated by O'nyong-nyong virus, 42.8% (95%CI: 37.6-47.5), Rift Valley fever virus, 32.0% (95%CI: 26.9-36.2), and chikungunya virus, 23.4% (95%CI: 19.0-27.4). Concurrent malaria infection and arboviral exposure were observed in 40.4% (95%CI: 35.6-45.4) of participants. No sociodemographic factors were significantly associated with co-exposure in the multivariable analysis. Conclusions: Substantial co-exposure of malaria and multiple arboviruses occurs in this remote Congo Basin setting. Integrated surveillance and improved diagnostics are urgently needed to guide febrile illness management and preparedness in under-resourced regions.