Study of the circulation of dengue, yellow fever, and West Nile viruses in Guinea: implications for achieving the health objectives of the Simandou 2040 program.

backgroundDiseases such as dengue, yellow fever and West Nile virus, which are transmitted by arthropods, pose public health problems in tropical and subtropical regions. Like many West African countries, Guinea possesses all the conditions conducive to the circulation of these viruses. These include local ecology and climate, as well as the presence of vectors that transmit these viruses. Despite their medical importance, these viruses have received limited study, and up-to-date information on their circulation remains scarce. In this context, the present study examined the prevalence of these three arboviruses (DENV, YFV and WNV) in human and vector populations. METHODOLOGY: This study covered 18 Guinea prefectures, which are spread across the country's four ecological zones. The study was conducted from 27 May to 27 November 2024. In health centers selected in each prefecture, 5 ml samples of venous blood were collected from asymptomatic patients aged 1-90 years who had visited for consultations and had given their consent. Additionally, mosquitoes were collected via an "AMPLECTA MOSQUITO TRAP" light trap. Two ELISA tests were performed on the blood samples: the first for detection and the second for confirmation of the presence of these viruses in human serum. The mosquito samples were analyzed to determine diversity, and real-time PCR was employed to check for viral infection in the vectors following viral RNA extraction via the RIBO-prep AmpliSens® Kit.

resultsSerological evidence of exposure to all three viruses in the eighteen surveyed prefectures indicates their widespread distribution across the country. The highest seroprevalence of dengue virus antibodies was observed in N'Zerekore (43.9% [38.5-49.4%]), whereas the highest seroprevalence of yellow fever virus antibodies was recorded in Kankan Prefecture (54.7%; 95% CI: 41.5-67.3). In Forecariah, up to 53.0% (95% CI: 42.4-63.4) of participants were seropositive for West Nile virus antibodies. Seropositivity for these arboviruses was more frequently observed among adults. Higher seroprevalence of dengue and yellow fever antibodies was also observed among farmers and livestock breeders. Higher seroprevalence of dengue and yellow fever antibodies was also observed among farmers and livestock breeders. No dengue or yellow fever infections were detected in the vectors, whereas the Culex quinquefasciatus population was found to be infected with WNV.

conclusionThis study provides serological evidence of exposure to dengue, yellow fever, and West Nile viruses across all the ecological regions of the Republic of Guinea. In addition, antibodies against these viruses were detected in human populations, and arbovirus-positive mosquito pools were identified during entomological investigations. Evidence of West Nile virus was also detected in mosquito pools containing Culex quinquefasciatus, suggesting a possible role of this species in the local transmission cycle. Adult farmers and livestock breeders appear to be at the greatest risk of contracting dengue and yellow fever. These results highlight the need for an integrated arbovirus surveillance system in Guinea. This system must combine serological surveillance with entomological surveys to support the public health objectives of the Simandou 2040 program.