Geo-epidemiology of Malaria in Burkina Faso, 2013-2018: a recent re-increase.

Introduction After a global decline, malaria cases re-increases have been shown recently. The aim of this analysis was to update the epidemiological facies of malaria in Burkina Faso (5% of malaria cases worldwide) by estimating weekly malaria incidences at health district levels, from 2013 to 2018, associated to environmental and meteorological factors. Methods Malaria case weekly reports were extracted by the National Malaria Control Program in Burkina Faso for each health district from 2013 to 2018. Population data were extracted from the reports of the national statistics council. Environmental data were collected from remote sensing. After estimating incidences through time and space, trend was assessed by an additive decomposition of the incidence and malaria seasons of transmission was estimated by change point analysis (PELT algorithm). Incidence maps, for each malaria season, were assessed to highlight spatial variability through years. Maps of rainfall, temperature, and vegetation (NDVI) were produced to characterize the health district environmental variability. Results In 2013, 775 cases /100,000 inhab.week were observed in average, and remain roughly constant until 2015. Malaria re-increased from 2016, reaching 2428 cases /100,000 inhab.week in 2018. From 2013 to 2016, two transmission periods were observed: low from January to July (included) and high from August to December (included). From 2017 to 2018, an intermediate transmission period from mid-November to early January intercalated between the low transmission period from mid-February to early June and the high transmission period from July to late December From 2013 to 2015, the most affected districts were located in the center and central-eastern part of the country. From 2016 to 2018 all health districts, except those in the Sahel region, were affected with at least 45,000 cases per 100,000 persons/year. This south-to-north gradient was also observed with rainfall, temperature and NDVI. Conclusion Malaria incidences re-increased through years and across the country since 2016. But no modification of the environmental factor variability was observed during the same period, in time or space. The re-increase of malaria in Burkina Faso could be due to a real increase of the disease, or to a better access to diagnostic and cure, together with the development of the epidemiological information system.