Burden and determinants of asymptomatic malaria among adults living in urban and rural areas in Gabon in 2023: a community-based cross-sectional study

Background: Asymptomatic malaria represents a major challenge for malaria control and elimination efforts, particularly in endemic regions such as Gabon, where adult reservoirs are under-investigated. This study aimed to assess the burden and determinants of asymptomatic Plasmodium falciparum infection among adults in urban and rural communities in Gabon. Methods: A community-based cross-sectional survey was conducted between January and December 2023 in Bitam (rural), Libreville, and Owendo (urban). Adults aged ≥18 years with no malaria symptoms or recent antimalarial treatment were included. Demographic, socio-economic, and ITN-use data were collected via structured questionnaire. Malaria was diagnosed by microscopy. Logistic regression models were used to identify factors associated with asymptomatic infection. Results: Among 1,496 participants, the overall prevalence of asymptomatic P. falciparum infection was 15.3%, significantly higher in rural areas (22.4%) than in urban settings (4.1%; p<0.01). Parasite densities were also higher in rural participants. Independent risk factors included rural residence (aOR: 7.1; 95% CI: [4.4–9.8]), being a worker (aOR: 5.2; 95% CI: [3.4–7.8]), and having primary or secondary education (aOR: 2.6; 95% CI: [1.6–4.0]). ITN use was low (32.7%) and not significantly protective in multivariate analysis. Conclusion: The substantial burden of asymptomatic malaria in adults, particularly in rural Gabon, underscores the need to broaden malaria control strategies. These interventions must be tailored to adult populations, considering occupational exposure and local transmission dynamics. Expanding screening and improving ITN access and use are critical to reduce the hidden reservoir and achieve malaria elimination.