Temporal trends and epidemiological patterns of Lassa fever outbreaks in Ebonyi State, Nigeria: A retrospective study (2018–2023)

Abstract

Ebonyi State in southeastern Nigeria has experienced a notably high number of deaths from Lassa fever (LF). Despite this, there is a dearth of studies on the epidemiological and management outcomes of LF outbreaks over the years. The study aims to describe and analyze the epidemiological and management factors of LF for a period of six years (2018-2023) in Ebonyi State with a view to informing targeted interventions, control, and prevention of LF in the state. Secondary data of the LF outbreak from January 2018 to December 2023 were obtained from the Ebonyi State Ministry of Health. The primary outcome was survival from LF, assessed by identifying predictors through logistic regression and estimating survival probability using survival analysis. Associations between demographic and clinical variables were evaluated using odds ratios, chi-square, and Fisher's exact tests. Geospatial mapping with ArcGIS explored the spatial distribution of LF cases. A total of 1,910 suspected cases were reported, with 368 confirmed. The case fatality rate (CFR)among confirmed cases was 33.97%, increasing yearly. Nearly half (49.7%) were from Abakaliki Local Government Area (LGA), showing a clustered spatial pattern. The median age was 32 years (IQR: 22-42), with 52.7% male. Dehydration (OR: 0.45), nausea/vomiting (OR: 0.57), neurologic disorders (OR: 0.33), bleeding (OR: 0.48), sepsis (OR: 0.39), and respiratory disorders (OR: 0.44) significantly reduced survival odds. Median time from symptom onset to hospital presentation was 10 days (IQR: 7-18), and from presentation to diagnosis was 12 days (IQR: 4-23). The CFR of LF in Ebonyi State is high, with Abakaliki LGA as the hotspot. Delays in hospital presentation and diagnosis exist. Regular community sensitization and improved training of medical personnel are needed to promote early symptom reporting and enhance timely LF management.