Simultaneous circulation of all four dengue virus serotypes during a single outbreak in Kassala, Eastern Sudan 2023

Dengue is one of the major health problems worldwide and Sudan is one of thecountries with high burden of the disease especially the eastern part which is endemic fordengue. This study aimed to identify the circulating dengue serotypes during the outbreak of thedisease in Kassala 2023. We prospectively enrolled 548 febrile patients suspected of dengue infection who visitedKassala teaching hospital between September 2023 and February 2024.Diagnostic confirmation was achieved through rapid tests (NS1 antigen, IgM, and IgG), and reverse transcription polymerase chain reaction (RT-PCR) was employed to identify various dengue serotypes. Of the 548 febrile patients, dengue was confirmed in 50.4% (276/548) using rapid diagnostic tests. Among these, the NS1 antigen was positive in 70.7% (195/276), while IgM was detected in 0.4% (1/276). Seropositivity for both NS1 antigen and IgM was observed in 27.5% (76/276), with IgM and IgG co-detected in 1.4% (4/276). Serotype differentiation via RT-PCR revealed that DENV-III was the most prevalent at 50% (133/266), followed by DENV-II at 39.8% (106/266). DENV-IV accounted for 3% (8/266), and a co-detection of DENV-II and DENV-III in same sample was observed in 4.9% (13/266) as well as serotypes I and III together constituted 2.4% (6/266). The patient demographic included predominantly males (56.8%, 151/276), laborers (45.7%, 126/276), individuals with secondary education (41.7%, 115/276), and urban residents (83.7%, 231/276). The mean age of patients was 32.1 ± 12.9 years. The most common symptoms included fever (100%), headache (95.7%), back pain (91.7%), joint pain (87.7%), sweating (84%), nausea (84.8%), chills (83%), and hemorrhagic manifestations (15.6%). Statistical analysis indicated significant associations between male gender (P = 0.014), headache (P = 0.040) and chills (P = 0.010) with dengue serotypes III. This study highlights the high prevalence of dengue infection among febrile patients at Kassala Teaching Hospital, with all four dengue virus serotypes being circulated duringthe outbreakof the disease 2023. Further large-scale studies, including genomic analyses of dengue, are essential to elucidate the relationships among dengue serotypes, genotypes, and clinical manifestations.