Study of patients with acute undifferentiated fever identifies dengue as a growing threat to public health in Mali

Résumé fourni par la source

The circulation of arboviruses in sub-Saharan African countries remains poorly documented. The associated health burden may be underestimated and masked by the significance of malaria. Here, we have investigated acute undifferentiated fevers for arboviral infections in Mali (2016-2024). To estimate the proportion of patients with arboviral infection, and in particular dengue. A retrospective (2016-2022) and a prospective (2023-2024) studies were conducted in patients from health centers and hospitals of Mali (mainly in the Bamako region) selected by health professionals. Studies included patients with acute fever lasting less than 7 days; the prospective sub-study excluding pyogenic, urinary, tuberculosis, viral hepatitis, typhoid fever and post-traumatic infections. Blood samples were tested for arboviruses using molecular detection (including serotyping) and genomic sequencing. We collected demographic data and results of malaria testing for all patients and, in the prospective study, a set of clinical data. A total of 2,022 patients were included. Dengue virus (DENV) was the most frequently detected pathogen (retrospective study: 7.6%, 16/210 patients; prospective study: 29.5%, 535/1812 patients). We also detected chikungunya virus (n = 7), West Nile virus (n = 2) and Rift Valley fever virus (n = 1). Three serotypes of dengue were identified: DENV-2 (n = 185), DENV-1 (n = 113) and DENV-3 (n = 105); 148 DENV cases could not be typed. For each serotype, phylogenetic analyses identified a major lineage recently originating from the subregion (DENV-1-III; DENV-2-II; DENV-3-III). In contrast to malaria, the dengue detection rate was higher among patients over 18 years of age. The most frequently observed symptoms were headache, asthenia, arthralgia, myalgia and back pain. The mean number of those symptoms per patient was significantly higher in dengue patients. We recorded 6 cases of hemorrhagic dengue, but no deaths and no case requiring transfer to intensive care. Our findings confirm the threat posed by arbovirus infections in Mali, and more specifically the growing burden of dengue fever on public health. Monitoring dengue fever has become a major challenge in sub-Saharan countries in order to determine the conditions necessary for the future implementation of a dengue vaccination policy tailored to the public health objectives of these countries.

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