Background: Bauchi State has been recording seasonal outbreaks of Lassa Fever (L.F) with increasing magnitudes, widening geographical spread and worsening mortality since 2012. Confirmed cases of L.F. have been reported since then and another outbreak of L.F was declared in Bauchi State on the 13th of November 2023. We investigated the outbreak and conduct its epidemiologic characterization in the state.
Method: We conducted active case searches for L.F. in affected communities, reviewed hospital and mortuary records. Blood samples were taken from suspected and high-risk cases for serology to confirm cases. Line-listed and followed up cases and contacts. Conducted data abstractions from case investigation forms, verbal autopsies, epidemiologic characterization of cases, environmental assessments and risk analysis across the state. We defined a suspected case as any person working or residing within the affected L.G.As and environment with fever of 380C, not responding to the usual anti-malarial or antibiotics within 24-72 hours with or without hemorrhagic symptoms, travel history, or contact with a known case between November, 2023 and March, 2024, and a confirmed case as any suspected case with laboratory confirmation (positive IgM antibody or viral isolation).Then, calculated required frequencies, proportions and associations.
Result: To date 171 cases were PCR-confirmed with L.F. with an attack rate(A.R) of 33.2% and case fatality rate (CFR) of 26.3%. The median age of the confirmed cases was 25 years (range: 0-62 years) with a slight male preponderance 96(56.2%). Although confirmed cases are being reported from the other senatorial zones, Bauchi South senatorial zone still accounted for most 162(94.7%) and the majority 107(62.6%) were now from Jama’a district of Toro LGA.
Conclusion: Outbreaks of L.F were confirmed in Bauchi State with widening geographical spread of confirmed cases, and increased CFRs since 2102. We intensified strategic risk communication and social mobilization activities to increase timely case detection and isolation. Recommended the development of a more efficient state emergency preparedness and outbreak response plan (EPR), strengthening of the State’s surveillance system and effective implementations of its preventive strategies.
Keywords: Lassa fever, Outbreak investigation, Attack rate, Case Fatality Rate, Bauchi state
