Enhancing Surveillance for Dengue Fever in Oyo State, Nigeria – a One Health Approach

Background The threat from Dengue Fever (DF) is fast becoming a global menace. The burden of DF in Oyo State and indeed in Nigeria remains unclear, as cases go underdiagnosed or misdiagnosed as malaria. This is attributable to poor health-seeking behavior of the population, weak surveillance systems, and poor health infrastructure. Consistent surveillance of this pathogen using a one-health approach is necessary to assess the public health impact, meteorological influence, vectoral abundance, high-risk groups, and locations associated with Dengue Virus (DENV) infections. Methods A cross-sectional study was conducted from Jan 2022 to April 2023. It involved screening DENV in 289 human blood samples and 1,015 Aedes species mosquitoes. Viral RNA was extracted and purified using Jena Bioscience Viral DNA + RNA purification kit. These were analyzed using the One-Step PrimeScript III RT-qPCR mix. Serological detection of DENV-specific antibodies IgM and IgG in humans was analyzed using a one-step lateral flow immunoassay cassette test kit. Patients who were DENV IgM positive were screened for Lassa Virus (LASV) to rule out coinfection. Adult Aedes mosquitoes were trapped using Biogents Sentinel Trap. Mosquitoes recovered were morphologically identified and classified using appropriate taxonomical keys. Meteorological data was obtained from NIMET. Data was abridged as proportions; correlation analysis was done to determine associations. Result The overall seroprevalence of DENV was 128/289 (44.2%) with 19/289 (6.6%) and 109/289 (37.7%) being IgM and IgG positive. DENV was detected all year round with more cases in the rainy season. LASV and DENV coinfection was detected in a participant. DENV RT-qPCR analysis in febrile patients and mosquitoes was negative. There was a high abundance of Aedes aegypti (79.5%) in all the locations surveyed with Aedes albopictus (12.3%) detected in Ido LGA and Ibadan South-East LGA while Aedes simpsoni (9.1%) was found at Iwajowa LGA. Mosquito populations varied during the study period in response to prevailing weather conditions. Conclusion The high seroprevalence in this study demonstrates an ongoing transmission and exposure to DENV in Oyo State, this further underscores the need to include DF as a differential diagnosis for febrile illnesses. Surveillance system strengthening, as well as timely, accessible, and sensitive laboratory diagnosis for DF, is advocated.