Abstract
Background: Brucellosis is an abortifacient zoonosis that represents a major burden on livestock productivity and public health in sub-Saharan Africa, yet baseline epidemiological and economic data for small ruminants remain limited or unavailable in many countries, including Benin. Despite small ruminants constituting the most numerically dominant livestock population and directly contributing over 6% to national Gross Domestic Product (GDP) there has been no structured serological investigation, or economic assessment, of brucellosis in Benin. Methods: A cross-sectional study was conducted from August 2024 to September 2025 across three municipalities of Benin (Parakou, Dassa-Zoumé and, Abomey-Calavi,). Sheep and goats (n = 308) were sampled from farms (n = 47) and screened for brucellosis using the Rose Bengal Test (RBT) for brucellosis screening. Species-specific seroprevalence was estimated with Wilson 95% confidence intervals. Risk factors were assessed using Firth’s penalized logistic regression on sex, municipality origin and species parameters. An epidemio-economic model, was further applied with the corrected true prevalence to estimate the monetary and population cost of inaction toward brucellosis in small ruminant production. The model used demographic parameters, brucellosis impact parameters on reproduction, and offtake market values, projected over 10-, 20-, 30-, and 50-year horizons and extrapolated to national scale under Monte Carlo simulation. Results: Overall seroprevalence was 6.17% (95% CI: 3.98-9.43%) at animal level and 29.79% (18.65-43.98%) at farm level. Species-specific seroprevalence was 6.21% (3.51-10.78%) in sheep and 6.11% (3.13-11.59%) in goats. Farm-level clustering was substantial (ICC = 0.459; MOR = 4.92), confirming the farm as the primary epidemiological unit of brucellosis risk. Multivariable Firth regression identified male sex (OR = 3.75; 95% CI: 1.18-10.63; p = 0.027) as significant risk factors. The annual economic cost of inaction was estimated at 6,629.70 FCFA (USD 11.73) per infected sheep and 3,851.26 FCFA (USD 6.82) per infected goat, accumulating to a median combined national-level loss of 12.81 billion FCFA (USD 22.67 million) over 10 years. Conclusions: This study confirms that brucellosis is endemic in small ruminant farms in Benin and provides the first municipality-level quantification of the economic losses attributable to the disease. Elasticity analysis identified wholesale price and abortion probability as the principal drivers of economic losses, with vaccination-based control strategies targeting abortion being the highest-return intervention. These findings provide a municipality-level, decision-ready evidence base for aligning a national brucellosis control programme with the One Health Joint Plan of Action framework.