A spatiotemporal analysis of bovine brucellosis cases in dairy herds from Argentina, from 2014 to 2023.

Brucellosis is a bacterial infection that causes abortion in cattle, poses a significant public health risk, and causes economic losses in livestock production. This study analyzed passive epidemiological surveillance data on brucellosis in Argentine dairy herds collected by the Brucellosis Laboratory LRS 0331, located at Estación Experimental Agropecuaria Rafaela of Instituto Nacional de Tecnología Agropecuaria, Argentina from 2014 to 2023. Positive herds were detected using indirect ELISA on bulk tank milk. The proportion of tested and positive herds was assessed by province and district, and high-risk spatiotemporal clusters were identified. The average number of dairy herds tested per year from 2014 to 2023 was 3,209.7 (SD = 555.9). The average percentage of dairy herds tested out of the total number of dairy herds was 27.1% in the whole country and 47.5% in the areas with a high density of dairy herds. The average rate of brucellosis positive dairy herds was 2.9% (SD = 0.54%) in the whole country and 1.6% (SD = 0.56%) in the high density area. Seven significant (P < 0.01) spatio-temporal clusters of high risk for brucellosis-positive herds were detected. Two of them were located in the high density area. Although this analysis was performed on the results of passive surveillance, the proportion of analyzed dairy herds is high, especially in the high density area. The prevalence of brucellosis in dairy herds in Argentina is low (2.9%) and has remained stable over the years. In Argentina, vaccination, testing and culling of positive animals is mandatory, but farmers bear the costs of veterinary services, laboratory analysis and culling. As a result, some farms do not determine their brucellosis status or take eradication measures. Previous studies have shown that compensation for culled animals is essential, thus monetary compensation could be a tool to reduce prevalence and eradicate the disease.