Epidemiological trends and clinical manifestations of Dengue in Sudan (2009-2015)

Abstract

Background: Dengue fever (DF) is a vector-borne disease, transmitted mainly by the female of the Aedes aegypti. The disease has now expanded geographically and by 2011 had reached 128 countries, with estimated that half of the population at risk annually Objective: To describe the epidemiological characteristics and the clinical manifestation of dengue fever, while highlighting gaps in the quality and completeness of the surveillance reporting over a seven-year period in Sudan. Methods: All dengue fever (DF) cases reported from 2009 to 2015 at the Sudan Federal Ministry of Health (FMoH) were retrospectively analyzed. Incidence and case-fatality rates were calculated, and described geographically, historically and demographically (age and gender). The clinical and laboratory characteristics of reported DF cases were also tabulated. Finally, variable-specific rates of incomplete reporting in records at the FMoH were studied. Results: There were 5,923 cases reported from five Sudanese states, especially in two peak outbreak years (2010 and 2014), of which 59percent were males and the mean age of cases about 20 years. The highest overall year-to-year incidence rate was 257.6 per 100,000 (95percent CI: 249.4-265.8) and the overall case fatality rate was 1.3percent. Outbreak case-loads continued a previously recorded decreasing trend. Of cases with laboratory results (55percent), 76.5percent tested positive for dengue, 62.4percent being a primary infection. The classical dengue fever clinical presentation was present in 90percent of cases, while the more serious hemorrhagic sub-type composed the remaining 10percent. The least completeness report was found for laboratory data (71.5percent). Conclusions: DF outbreaks in the studied years in Sudan are characterized by lower relative severity and low fatality rate. In the five-state involved, two Eastern ones (Red Sea and Kassala) are known to be endemic, while the disease was considered as emergent in three Western states (North Darfur, South Kordofan and North Kordofan). Outbreaks in the former are linked to peak