Seroprevalence and Risk Factors of Brucellosis in Sedentary Livestock Farms of Hadjer-Lamis Province (Chad)

Brucellosis remains a major bacterial zoonosis affecting both livestock health and public health, causing severe economic losses in developing countries. This study aimed to determine the seroprevalence of brucellosis and identify the associated risk factors within sedentary livestock farms in Hadjer-Lamis Province, Chad. A cross-sectional epidemiological study was carried out between May 2024 and September 2025. A total of 299 blood samples were randomly collected from cattle, sheep, goats, and dromedaries in various sedentary farms. The collected sera were systematically screened using the Rose Bengal Test (RBT) to detect antibodies against Brucella spp. The overall seroprevalence of the region was 6.69% (20/299). Among the tested animals, cattle exhibited the highest prevalence rate at 8.86%. Following multivariate logistic regression analysis adjustment, only the cattle species demonstrated a significant association with brucellosis seropositivity (aOR = 3.21; 95% CI : 1.07–9.62 ; p = 0.038). This field study confirms the active circulation of Brucella spp. in Hadjer-Lamis Province. The findings highlight an urgent public health need to introduce the Rose Bengal Test as a mandatory sanitary prerequisite before the commercialization of fresh raw milk or its processing into dairy products in sedentary livestock farms to mitigate human contamination risks.