Spatial overlaps in the distribution of HIV/AIDS and malaria in Zimbabwe

Abstract

Background: In most developing economies particularly in Africa, more people are likely to die of HIV/AIDS and malaria compared to other diseases. HIV/AIDS tends to be superimposed on the long standing malaria burden particularly in sub-Saharan Africa. The detection and understanding of spatial overlaps in disease occurrence is important for integrated and targeted disease control. Integrated disease control can enhance efficiency and cost-effectiveness through the development of drugs targeting multiple infections in the same geographic space.

Methods: Using Zimbabwe as a case study, this study tests the hypothesis that malaria clusters coincide with HIV/AIDS clusters in space. Case data for the two diseases were obtained from the Ministry of Health and Child Care in Zimbabwe at district level via the District Health Information System (DHIS). Kulldorff's spatial scan statistic was used to test for spatial overlaps in clusters of high cases of HIV/AIDS and malaria at district level. The spatial scan test was used to identify areas with higher cases of HIV/AIDS and malaria than would be expected under spatial randomness.

Results: Results of this study indicate that primary clusters of HIV/AIDS and malaria were not spatially coincident in Zimbabwe. While no spatial overlaps were detected between primary clusters of the two diseases, spatial overlaps were detected among statistically significant secondary clusters of HIV/AIDS and malaria. Spatial overlaps between HIV/AIDS and malaria occurred in five districts in the northern and eastern regions of Zimbabwe. In addition, findings of this study indicate that HIV/AIDS is more widespread in Zimbabwe compared to malaria.

Conclusions: The results of this study may therefore be used as a basis for spatially-targeted control of HIV/AIDS and malaria particularly in high disease burden areas. This is important as previous interventions have targeted the two diseases separately. Thus, targeted control could assist in resource allocation through prioritising areas in greatest need hence maximising the impact of disease control.

Keywords: Disease clusters; GIS; HIV/AIDS; Malaria; SaTscan; Spatial overlap.

Fig. 1

Spatial distribution of annual (a) HIV/AIDS and (b) Malaria prevalence per 1000 of the population in Zimbabwe in 2016

Fig. 2

Distribution of HIV/AIDS and malaria primary and secondary clusters and their relative risk in Zimbabwe. Black Circles indicate HIV/AIDS clusters while the red circles indicate malaria clusters. Districts with hatching pattern indicate areas in which HIV/AIDS and malaria overlap in space. The letters h and m on the cluster numbers indicate HIV/AIDS and malaria clusters, respectively. RR denotes reletive risk