Spatio-temporal dynamics of malaria incidence in children under five years of age and correlation with meteorological variability in the North and Far North regions of Cameroon between 2015-2022

Changes in environmental temperature, humidity, and rainfall can affect the survival and behavior of the mosquito vector of malaria parasites, thereby influencing malaria incidence rates. We investigated the spatiotemporal dynamics of malaria incidence in two geo-epidemiological transmission zones (North and Far North regions) of Cameroon and assessed its correlation with various meteorological factors. Malaria and meteorological data were obtained from the local health information system and by remote sensing, respectively. Malaria risk was stratified according to spatial heterogeneity of incidence. The strength of the association between malaria incidence and meteorological variables was measured using distributed lag nonlinear models (DLNM). A generalized additive quasi-Poisson regression model was used to account for over-dispersion in the number of cases. The values observed during the non-epidemic season were used as exposure reference values for the effects predicted by the DLNM. Between 2015 and 2022, the maximum recorded incidence was 190.6 (189.5-191.8) per 1000 person-years for the North region and 243.8 (242.9-244.7) for the Far North region. Stratification of health districts by malaria risk showed that most health districts are located in areas of very low to low transmission. From more than one millimeter rainfall per day (1 mm/day) on average, the risk of malaria transmission was 1.2 times higher (RR = 1.2, 95 % CI: 1.1-1.2) in the North region and 1.4 times higher (RR = 1.4, 95 % CI: 1.3-1.5) in the Far North region and increased with rainfall intensity. Humidity at 70 % increased the risk of transmission 2 times higher (RR = 2, 95 % CI: 1.4-2.8) in the North region and 3.7 times higher (RR = 3.7, 95 % CI: 2-4.6) in the Far North region. Collectively, the data reveal significant year-to-year variations in malaria incidences in the North and Far North regions of Cameroon, and a strong association with meteorological factors such as humidity and rainfall.