Epidemiological trends and animal-human relationships of brucellosis in Algeria from 2010 to 2022: A one health approach.

Brucellosis is a bacterial disease transmitted from livestock to humans, causing fever, joint pain, and reproductive disorders in animals and people. In Algeria, tens of thousands of human cases are reported, yet animal sources are incompletely captured by routine surveillance. Thus, a retrospective epidemiological study using 13 years of national human surveillance data, combined with a cross-sectional seroprevalence survey of 816 dairy cattle in eastern Algeria, was carried out to better characterize the epidemiological link between human and animal brucellosis. Cattle blood samples were screened using the Rose Bengal Plate Test (RBPT), with positive cases confirmed by indirect ELISA (cELISA). As a result, human incidence peaked at 27 per 100,000 in 2018, with two wilayas accounting for over 40% of cases. Similarly, in cattle, an overall seroprevalence of 18.01% (95% CI: 15.43-20.85) was observed, with marked geographic variation ranging from 0% to 30%. Cattle with retained placenta were 6.53 times more likely to be seropositive (aOR=6.53; 95% CI: 4.18-10.29). Notably, we observed nearly 12 times more reported human cases than animal outbreaks, underscoring a major gap in surveillance. Monitoring reproductive failures in cattle can therefore serve as an early warning for human risk, and control will require coordinated veterinary and public health action under a One Health approach.