Strengthening diagnostic capacity for viral hemorrhagic fevers in Forest Guinea: advances in Lassa fever case detection

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Abstract Viral hemorrhagic fevers (VHFs), including filoviruses, Lassa virus, yellow fever virus and dengue virus, remain a major public health threat in resource-limited settings. The 2014–2016 Ebola epidemic exposed critical gaps in laboratory preparedness and diagnostic capacity in most-at-risk countries, including Guinea. In order to implement sustainable in-country laboratory capacity for early detection and rapid response to VHF outbreaks, a decentralized diagnostics laboratory strengthening program started in the forested region of Guinea in Guéckédou (2017) and N’Zérékoré (2021). Between 2017 and 2024, a total of 4683 samples from suspected VHF cases were tested across the two laboratories. Of those, 47 (1%) were identified as positive for VHFs by molecular testing, including the 2021 Ebola virus disease resurgence and Marburg virus disease emergence samples, for which the laboratories supported rapid outbreak detection and case management. Notably, between 2020 and 2024, 30 Lassa fever cases were laboratory-confirmed with a case fatality rate of 67.9%. Of those, 66.7% were men, with 50.0% and 27.6% of the cases originating from the Guéckédou and N’Zérékoré prefecture, respectively. Prior to this program, Lassa fever detection in Guinea remained anecdotic. One case of yellow fever and one of dengue were also identified by molecular assays. The establishment of locally embedded laboratory infrastructure enhanced VHFs preparedness, surveillance, and response in Guinea. Beyond improving understanding of Lassa fever epidemiology, this program highlights the value of sustained laboratory capacity for early detection and health system resilience in VHF-endemic settings.