Spatial Clustering of Dengue Fever and Urban Water Storage: A Policy Analysis for Kinondoni Municipality, 2017

Dengue fever is a significant public health threat in urban Africa, intensified by climate variability and unplanned urbanisation. In Dar es Salaam, Tanzania, unreliable piped water supplies compel widespread household water storage, which can create breeding sites for the Aedes mosquito vector. Kinondoni Municipality reports recurrent outbreaks, but the spatial links between cases and water storage practices are not well defined for policy. This analysis aimed to identify spatial clusters of dengue fever cases in Kinondoni Municipality and examine their association with common urban water storage practices. The objective was to produce spatially explicit evidence to guide local vector control and urban health policy. A retrospective, ecological study design was used, analysing secondary data. Laboratory-confirmed dengue cases were geocoded. Spatial autocorrelation was measured using Global and Local Moran's I statistics to identify significant case clusters. These clusters were analysed against spatial data on water storage practices, including container density and type, derived from municipal environmental health surveys. A significant high-high cluster of dengue cases was identified in the central and coastal wards. A strong spatial correlation was found between this cluster and areas with a high density of improperly covered water storage containers, particularly 200-litre drums used for long-term storage. A majority of cases within the primary cluster were located in sub-wards where a high proportion of households reported inadequate container covering. Dengue transmission in Kinondoni shows distinct spatial patterning, closely associated with localised water storage behaviours necessitated by water infrastructure deficits. Existing blanket vector control policies are inadequately targeted to address these specific, high-risk micro-environments. Policy should prioritise targeted, ward-level interventions integrating community-led container management programmes with improvements to municipal water supply reliability. Vector control resources should be redirected towards identified high-risk clusters, focusing on promoting safe water storage practices and container covering. dengue fever, spatial clustering, water storage, urban health, vector control, policy analysis, Tanzania This analysis provides spatially explicit evidence linking dengue fever clusters to specific water storage practices, offering a rationale for moving from uniform to geographically targeted vector control policies in water-insecure urban settings.