Spatial and Space-time Clustering of Diarrhoeal Cases among Under-Five Children in Karkala, Karnataka: A Geospatial Analysis

Introduction: Globally, India tops by contributing the maximum number of diarrhoeal fatality. Forecasting the path and spread of diarrhoeal disease is critical due to its multifactorial cause, which needs robust spatial analysis and experiential investigations of communicable disease. Aim: To investigate purely spatial, purely temporal, and space-time clusters of diarrhoea among under-five children using a Geographic Information System (GIS) in Karkala taluk of the Udupi district of Karnataka, India. Materials and Methods: A retrospective longitudinal study was conducted involving all the primary health centres of Karkala taluk by the investigators, from the Department of Public Health, K S Hegde Medical Academy, Nitte (DU), Mangalore, Karnataka, India. The data on diarrhoea among under-five children was collected for three years, i.e., from 1st April 2015 to 31st March 2018, at the Udupi district health office. A total of 49 village data were obtained, and 3894 under-five childhood diarrhoea were reported during the study period. The annual incidence of childhood diarrhoea at the taluk level was calculated using excel. The spatial, temporal and space-time diarrhoeal clusters were identified using Kulldorff SaTScan software. Geographic Information System, QGIS 3.20.2 software was used to plot the maps. Results: The analysis of the spatial cluster using SaTScan software for three years in the study area identified eight high-risk areas (p-value<0.0001), covering 17 villages. The most likely spatiotemporal cluster region was located at the northern Karkala, and the most-at-risk period was 1st April 2016 to 30th September 2017 {Log Likelihood Ratio (LLR) = 114.67 and p-value < 0.00001}. The analysis of purely temporal cluster showed that one most likely cluster happened in all villages (LLR = 73.89, p-value < 0.001) from 1st April 2017 to 3rd March 2018. Conclusion: The diarrhoea among under-five children at Karkala taluk was not randomly distributed over space and time.