First laboratory-confirmed fatal dengue virus infection and its implications for national arboviral surveillance in Liberia

Introduction Dengue Virus (DENV) is an emerging public health threat in Africa, where its impact is underestimated due to non-specific clinical manifestations and restricted diagnostic capabilities. In Liberia, laboratory-confirmed cases of DENV were initially recorded in an urban febrile surveillance study (2018–2020), yet severe or fatal outcomes had not been previously reported. This paper reports the first laboratory-confirmed fatal dengue case and its implications for national surveillance and policy in Liberia. Case Report On February 2, 2026, a 38-year-old Liberian male arrived at J.J. Dossen Hospital in Maryland County, located in the Southern region of Liberia, who presented with a two-day history of high fever, severe headache, myalgia, weakness, and abdominal discomfort. He had no recent history of travel. The first laboratory investigation using rapid test and microscopy ruled out malaria. Molecular detection performed at the National Public Health Reference Laboratory (NPHRL) was negative for Lassa, Ebola, and Marburg. Despite management with supportive care, his condition deteriorated clinically upon re-admission, and the patient died on February 6, 2026. Serological testing performed at an external laboratory in Ghana detected DENV IgG antibodies and a positive NS1 antigen result, prompting further investigations. Consequently, blood sample was referred to the Institut Pasteur de Dakar, Senegal, where confirmatory testing was conducted to include differential RT-PCR for a diverse array of arboviruses and viral hemorrhagic fevers and differential viral-specific IgM ELISA. The sample tested positive for DENV RNA by RT-PCR, negative for other viruses and negative for Dengue-specific IgM. The absence of detectable IgM may reflect specimen collection during an early stage of infection before seroconversion. However, IgM negativity alone cannot distinguish between primary and secondary infection. Conclusion This is the first molecular confirmation of fatal dengue in Liberia. It highlights the potential for severe outcomes and indicates local transmission in a rural, cross-bordered region of the country. There is critical need for swift implementation of integrated arboviral surveillance in both urban and rural settings, better diagnostic capabilities, and possibly a nationwide sero-epidemiological study to estimate the actual burden of dengue in the country.