Serological Evidence of Dengue Virus Exposure and Possible Active Infection in Stored Serum Samples from a University Medical Centre in Ilara-Mokin, Southwest Nigeria

Abstract

Dengue virus infection is a major global public health concern; however, its true burden in many parts of sub-Saharan Africa, including Nigeria, remains underrecognised and often misdiagnosed, particularly in malaria-endemic settings. This pilot surveillance study aimed to investigate the serological evidence of dengue virus exposure and active infection in a university community in southwest Nigeria. A total of 106 stored serum samples from patients who sought care at Elizade University Medical Centre were analysed. Samples were tested for dengue virus NS1 antigen (NS1Ag) and IgG/IgM antibodies using the SD BIOLINE Dengue Duo rapid diagnostic kit. Descriptive statistics were used to analyse the demographic data and prevalence of dengue markers. Overall, 22.64% (24/106) of individuals whose stored serum samples were analysed showed serological evidence of dengue virus infection (any marker positive). One individual (0.94%) tested positive for NS1Ag, indicating an acute infection. IgM antibodies, suggestive of recent infection, were detected in nine individuals
(8.49%), while IgG antibodies, indicating past exposure, were found in 22 individuals (20.75%). Males showed a positivity rate (27.94%;  19/68) compared to females (13.16%; 5/38). Among the 90 participants with age data, younger age groups (<20 years: 30.00%; 20-29 years: 26.00%) showed higher positivity. Among the 92 participants with known states of origin, Ondo State residents showed the highest positivity (33.33%; 9/27), followed by Bayelsa (29.17%; 7/24) and Delta (17.14%; 6/35). This pilot study provides serological evidence of
both recent and past dengue virus infections in the Ilara-Mokin university community, suggesting local transmission and a notable level of exposure to the virus. These findings underscore the need for increased awareness, enhanced surveillance, and the integration of dengue diagnostics into routine febrile illness management in Nigeria to accurately determine its prevalence and mitigate its public health impact. Further studies, including molecular characterisation, are required.