INFLUENCE OF BIOCLIMATIC CONDITIONS ON REPORTED UNCOMPLICATED AND SEVERE MALARIA CASES IN THE SECOND DISTRICT OF COTONOU, BENIN

Abstract

Malaria remains a major public health concern in Benin, and its seasonal pattern may be influenced by local climate. This study examined associations between bioclimatic conditions and reported uncomplicated and severe malaria cases in the second district of Cotonou. Monthly temperature, relative humidity and rainfall data for 1995-2024 were obtained from Météo-Bénin, while monthly malaria data for 2005-2024 were obtained from the Littoral Departmental Health Directorate. A field survey involving 142 adults provided contextual information on local vulnerability and adaptation. Two study-specific indicators, an air enthalpy index and an adjusted rainfall-temperature index, were calculated. Monthly patterns were described and exploratory Pearson correlations were estimated using 12 calendar-month observations. The district has a subequatorial climate with two rainy and two dry seasons. Reported uncomplicated malaria cases peaked in July at 2743, whereas severe malaria cases peaked in August at 1050. Rainfall correlated more strongly with uncomplicated malaria (r=0.419) than with severe malaria (r=0.096). Relative humidity showed correlations of r=0.641 with uncomplicated malaria and r=0.528 with severe malaria. The adjusted rainfall-temperature index correlated moderately with uncomplicated malaria (r=0.396) but only weakly with severe malaria (r=0.070). The hypothesis was therefore partially supported: climatic conditions were more closely associated with uncomplicated malaria than with severe disease. Climate-informed surveillance and intensified vector-control activities should be prioritized before and during high-risk rainy months, while the ecological design and absence of population denominators require cautious interpretation.