Risk factors for bovine tuberculosis persistence in beef herds of Southern and Central Spain

In order to assess risk factors related to bovine tuberculosis (bTB) persistence, a case-control study, comparing persistent versus transient bTB infected beef farms from Central and Southern Spain, was conducted. Farms were matched by herd size and geographical location (county). A questionnaire administered by personal interview was conducted on 150 herds (80 controls and 70 cases) from Andalucia and Castilla La Mancha regions. The questionnaire included questions related to the personnel involved in routine diagnostics, structure of the farm and of the herd, management, presence of other domestic species and of wildlife reservoirs.According to the results of our study, farms with large pasture areas and bTB infected neighbors had more difficulties in eradicating the disease, and therefore, were more likely to suffer a persistent bTB infection. The odds of bTB persistence were between 1.2 and 5.1 (i.e., 95% confidence interval of the OR) times higher in those herds that had a neighbor infected herd. Farms with large pasture areas had odds between 1.2 and 12.7 (i.e., 95% confidence interval of the OR) times higher of having a persistent bTB episode than farms with small pasture areas.