Precipitation Associated with Increased Diarrheal Disease in Mozambique; A Time Series Analysis

Abstract

Background Diarrheal diseases are a leading cause of morbidity and mortality in Africa. Though research has shown diarrheal diseases to be impacted by weather, there is limited evidence of this association in sub-Saharan Africa and no studies conducted in Mozambique. Our study aimed to determine if variation in diarrheal disease counts was associated with precipitation in Mozambique. Estimating this association is the first step in an effort to determine whether the relationship is robust enough to support developing an early warning system to improve health system preparedness and response, and to project future burdens of diarrheal disease associated with climate change. Methods Weekly diarrheal disease data were available for 1997-2014 from the Mozambique Ministry of Health (n = 7,324,661). We estimated the association between cases of disease and precipitation, defined as the number of wet days (precipitation > 1mm) per week, in each of Mozambique’s four regions, comprising a total of 141 districts. Time series analyses were conducted using a distributed lag Poisson regression model. Models were adjusted for time, maximum temperature, and district. Results Using a four-week lag, chosen a priori, we found that precipitation was associated with diarrheal disease in adjusted models. One additional wet day in a week was associated with a 1.86% (95% CI: 1.05-2.67%), 1.37% (95% CI: 0.70-2.04%), 2.09% (95% CI: 1.01-3.18%), and 0.63% (95% CI: 0.11-1.14%) increase in diarrheal disease in Mozambique’s northern, central, southern, and coastal regions, respectively. Conclusions Our study indicates a strong association between diarrheal disease and weather. Additional diarrheal prevention efforts should be targeted to areas with increased rainfall. As climate change increases the number of wet days and heavy precipitation, the burden of diarrheal disease in Mozambique may increase unless additional health system interventions are undertaken.