Spatio-temporal epidemiology of intestinal infectious diseases in Blantyre District, Malawi

Intestinal infectious diseases remain among the leading causes of death, mainly in sub-Saharan Africa. In Malawi's commercial hub, Blantyre, the spatiotemporal dynamics of these diseases have not been extensively studied, despite their significant public health burden. We studied high-risk areas and analyze the spatial and temporal patterns of intestinal infectious diseases, including cholera, schistosomiasis, and Other Diarrheal Diseases (ODDs) in Blantyre district from 2018 to 2023. Descriptive statistics were used to evaluate the epidemic characteristics of the intestinal infectious diseases. Spatial autocorrelation with Local Moran's I was employed to detect spatial clusters, and the Kulldorf retrospective method for space-time analysis. ODDs had the highest incidence rates, ranging from 2714/100,000 to 3631/100,000, while cholera had the lowest, ranging from 0 to 320/100,000. Temporal characteristics showed that ODDs and cholera peaked during the rainy season (October-March), while schistosomiasis occurred from April to June. Spatial clustering of schistosomiasis declined from two High-High (HH) clusters in Blantyre's northern and western parts (2018- 2020) to one (2021-2023). Cholera exhibited High-High (HH) clusters only in the northern part from 2021 to 2023. ODDs expanded from two to three HH clusters extending southward between 2018-2020 and 2021-2023. Space-time analysis identified nine most likely clusters for schistosomiasis and ODDs and two for cholera. Most likely, clusters were in the city, with secondary clusters in the northern and western parts. Given their high incidence, focused public health strategies for schistosomiasis and ODDs should be prioritized in future planning.