Malaria epidemics detection and associated climatic factors in the Hauts Bassins Health Region of Burkina Faso

Abstract

Background: Malaria is endemic in the Hauts Bassins Health Region, making it necessary to detect epidemics. Though malaria is a climatic sensitive disease, the association between malaria occurrence and climate is not well known in the Hauts Bassins Health Region. The study sought to detect malaria epidemics and assess the correlation of malaria cases with climate. Methods: A secondary analysis of ecological data from the National Health Information System (NHIS) and the General Directorate of Meteorology of Burkina Faso was conducted. Mean, quartiles and cumulative sum methods were performed to set epidemic thresholds. Correlation between malaria and climatic factors in the health region was assessed using Spearman's test. A Mann-Whitney test determined the association of malaria transmission seasons with climatic variables, at 5%. Kruskal-Wallis test evaluated the relationship between malaria and the years of the occurrence, at a 5% significance level. Results: From 2013 to 2016, 2,521,789 malaria cases were reported in the region, with a mean incidence of 269 cases per 10,000 people. The annual incidence increased from 2,048 cases per 10,000 people in 2013 to 5,277 cases per 10,000 people in 2016. Regardless of the method used, cases were high in 2016, with few exceptions. There was a weak negative correlation between malaria and minimum (r=-0,292; p-value=0.044) and maximum (r=-0,391; p-value=0.006) temperatures. The relationship between relative humidity and malaria was positive and weak (r=0,304; p-value=0.036). Lowest temperatures and highest relative humidity simultaneously drove malaria within-year variability during the high transmission season. Conclusion: Malaria incidence increased unexpectedly in 2016. Malaria endemicity hides a within-year and year-to-year variability, partially driven by the temperature, relative humidity and rainfall.