Spatio-temporal patterns observed during the 2008-2009 cholera outbreak in Zimbabwe

Cholera has emerged as a major threat to public health in Zimbabwe. One of the largest cholera outbreaks in recent history in the country occurred during 2008-2009 resulting in about 100,000 reported cases and a case fatality ratio of about 4.3%. Using weekly district level data on reported cholera cases and deaths obtained from the Zimbabwe Ministry of Health and Child Welfare (MoHCW), we carried out spatio-temporal analysis of the outbreaks to identify areas with an increased burden of disease and described the spatial patterns of the epidemic. Results show that the distribution of cases and deaths was spatially heterogeneous. Cumulative attack rates/100,000 population varied widely ranging from 4.3 (95% CI: 3.0, 6.0) in Shurugwi to a high of 4943.8 (95% CI: 481.1, 508.1) in Beitbridge. Case fatality ratios also showed wide variation ranging from 0% (95% CI: 0, 41) in Lupane to 29.6% (95% CI: 23.2, 36.7) in Murehwa. Clustering was identified in districts in the northern, eastern, and south eastern borders of the country. These areas have a history of previous cholera outbreaks and highlight the need for targeted interventions. Cholera deaths were shown to be higher in the rural districts of the country, suggesting poor access to health care facilities or basic oral rehydration solution for cholera treatment. The findings here point to the importance of recognizing the heterogeneous nature of cholera outbreaks and the need to identify key factors that may help improve surveillance and disease control.