Descriptive epidemiology of Lassa fever outbreak in Taraba State, Nigeria, 2025

Introduction: Lassa fever (LF) is endemic in West Africa, representing a significant public health security threat. While Nigeria bears the highest burden, detailed state-level epidemiological data, particularly in North-Eastern states like Taraba, remain scarce. This study provided a comprehensive descriptive epidemiological pattern of Lassa fever in Taraba State from epidemiological weeks 1 – 7, 2025, addressing a critical evidence gap and informing targeted public health interventions. Methods: We conducted a descriptive epidemiological study analysing Taraba State surveillance and contact tracing data during the outbreak response from epidemiological week 1 – 7, 2025. A suspected case was defined as any person with malaise, fever, headache, sore throat, cough, nausea, vomiting, diarrhoea, myalgia, chest pain, hearing loss and a history of contact with rodent excreta or with a case of Lassa fever, while a confirmed case was defined as a suspected case that is laboratory-confirmed with Reverse-Transcription Polymerase Chain Reaction. We reviewed response logs, risk communication, and medical supply distribution. Descriptive statistics, including frequencies, proportions, positivity rate, and case fatality rate (CFR), were calculated, and the temporal distribution was analysed. Results: A total of 165 suspected cases were reported, of which 70 (42.6%) were laboratory-confirmed cases. Three suspected cases (1.8%; 3/165) occurred among healthcare workers. Thirty-seven confirmed cases died, giving a case fatality rate of 52.9%. The 15- 24-year age group accounted for 40.6% (67/165) of suspected cases, and 52.7% (87/165) were male. Bali LGA recorded the highest positivity rate (67.7%; 23/35), accounted for the highest proportion of confirmed cases (32.9%; 23/70) and high CFRs were noted in Ibbi and Wukari LGA (100%), Gassol (75%), Ardo-Kola (53.3%) and Bali (52.2%). The outbreak peaked during epidemiological week 4 (late January 2025). Conclusion: The Lassa fever outbreak in Taraba State was characterised by a high CFR, concentration of cases among young adult males and the epidemiological week 4 peak necessitated immediate and targeted public health interventions, including strengthening surveillance, implementing intensive community awareness campaigns for high-risk groups, and ensuring prompt access to life-saving treatment in high-burden LGAs.