Seroprevalence of Lassa Virus Infection and Associated Risk Factors in North-Central Nigeria: A Community-Based Multi-State Study

Abstract

Background: Lassa fever remains a major public health threat in West Africa, with Nigeria accounting for the highest burden of disease. However, the true extent of population-level exposure is poorly defined, particularly in North-Central Nigeria. Methods: A community-based cross-sectional seroprevalence of LASV was conducted across five states in North-Central Nigeria (Benue, Kogi, Nasarawa, Plateau, and the Federal Capital Territory-FCT) between January and July 2024. A total of 958 participants were enrolled using a multistage sampling method. Serum samples were tested for LASV-specific IgG and IgM antibodies using a validated recombinant nucleoprotein enzyme-linked immunosorbent assay. All IgM-positive samples and a random subset of IgM-negative samples underwent RT-PCR testing for the detection of active infection. Standardised questionnaires captured sociodemographic, environmental, and behavioural exposures. Multivariable logistic regression was used to identify factors independently associated with seropositivity. Results: IgM seroprevalence was low (1.15%), and all 91 samples tested by RT-PCR were negative. In multivariable analysis, participants from FCT (adjusted odds ratio [aOR] 0.07, 95% CI 0.03–0.15), Kogi (aOR 0.05, 95% CI 0.02–0.14), Nasarawa (aOR 0.18, 95% CI 0.09–0.40), and Plateau (aOR 0.22, 95% CI 0.10–0.49) had significantly lower odds of IgG seropositivity compared to Benue State. Living in non-concrete houses was associated with increased odds of seropositivity (aOR 2.66, 95% CI 1.79–3.95). In contrast, rodent consumption was associated with reduced odds of seropositivity (aOR 0.23, 95% CI 0.12–0.44). Conclusion: LASV exposure is widespread but heterogeneously distributed across North-Central Nigeria, with strong influence from geographical and housing-related factors.