Detection of dengue virus serotype 4 in Sudan.

Background: Dengue virus infection is spreading globally and most parts of Sudan have witnessed repeated dengue outbreaks, with the detection of DENV-1, DENV-2 and DENV-3 serotypes.

Aims: In this report we describe the dengue fever outbreaks that occurred in eastern Sudan (Kassala and Port Sudan cities) from August to November 2019.

Methods: We enrolled 79 (29.8%) suspected cases from Kassala and 186 (70.2%) from Port Sudan who presented with fever. The participants were medically examined and their clinical signs recorded. Blood samples were collected for complete blood count, detection of anti-dengue virus IgM, detection of NS1 dengue antigen and identification of the virus serotype using RT-PCR.

Results: The main clinical presentations were fever, abdominal pain, joint pain and vomiting, and thrombocytopenia was the main laboratory finding. One hundred and twenty-five blood samples tested positive for the anti-dengue IgM antibody, and 145 were positive for the NS1 antigen. Using RT-PCR, we identified 35 (24%) infections with DENV-2, 100 (69%) with DENV-3 and 10 (7%) with DENV-4 serotypes.

Conclusions: We identified multiple serotypes - DENV-2, DENV-3 and DENV-4 - as the causes of the outbreak. The presence of DENV-4 serotype was documented for the first time in Sudan.