A serologic study of dengue in northwest Ethiopia: Suggesting preventive and control measures

Background: Dengue is one of the most serious and rapidly spreading arboviral diseases in the world. Despite many acute febrile illnesses in Ethiopia, the burden of illness due to dengue in the country is largely unknown. Thus, the present study aimed to provide the first baseline data on seroprevalence and associated risk factors of dengue virus (DENV) infection in the country. Methods: A cross-sectional study of febrile patients who were visiting Metema and Humera hospitals in Northwest Ethiopia from March 2016 to May 2017 was conducted. Blood samples were collected from each participant and serum samples were separated and tested for IgM and IgG antibodies against DENV infection by enzyme-linked immunosorbent assay (ELISA). Risk factors associated with the prevalence of anti-DENV antibodies were tested using logistic regression analysis. Results: Of the 600 samples tested, the overall seroprevalence against DENV infection was 33.3%, while the seroprevalence by the study area was 40% in Metema and 27.5% in Humera. The overall prevalence of IgM and IgG antibodies against DENV infection was 19% and 21% respectively. Of these, 6.7% were positive for both IgM and IgG antibodies. Residence and occupational status were significantly associated with the prevalence of anti-DENV IgM seropositivity and anti-DENV IgM-/G+serostatus. The seasonal variation was significantly associated with the prevalence of anti-DENV IgM but not with anti-DENV IgM-/G+serostatus. The prevalence of anti-DENV IgM-/G+serostatus was significantly higher in Metema than Humera. High prevalence of anti-DENV IgM seropositivity was found in the summer and spring, with a peak in the month of August. The presence of uncovered water either indoor or outdoor and lack of mosquito net use was identified as risk factors for DENV infection. Conclusions: These findings provide the preliminary data on seroprevalence and associated risk factors of DENV infection in the country. The presence of antibodies against DENV infection indicates dengue as one of the causes of undifferentiated febrile illnesses in the study areas. This suggests that prevention and control measures should be designed considering the risk factors identified by this study. Furthermore, we recommend a large-scale study to include DENV infection in the differential diagnosis of all febrile illnesses in Ethiopia. Author summary: Despite dengue is currently one of the leading causes of arboviral diseases in the globe, it is unrecognized and underreported in Africa, particularly in Ethiopia. Thus, we conducted a cross-sectional study among febrile patients who were attending health institutions to document seroprevalence and associated risk factors of DENV infection in the country. The study illustrated the presence of antibodies against DENV infection for the first time in both study areas, an awaking message for those who were involved in health sectors. Most of the active DENV transmission was found in monsoon and post-monsoon periods with a peak in the month of August. In multivariate analysis residence, occupational status and seasonal variations were significantly associated with the prevalence of anti-DENV IgM seropositivity. Moreover, individuals who lack a mosquito net use and the presence of uncovered water storages either indoors or outdoors were identified as the risk factors of DENV infection. Therefore, we recommend that preventive measures should be considered. Moreover, nationwide surveillance should be carried out at large.