Risk factors associated with the seroprevalence of paratuberculosis in sheep flocks in the hot-arid region of Sonora, Mexico

Paratuberculosis is caused by Mycobacterium avium subspecies paratuberculosis (MAP), a chronic disease of a negative economic impact on sheep production. In the state of Sonora, Mexico, there are no reports on the prevalence of MAP in sheep and risk factors associated with it. The objective of this study was to estimate the seroprevalence of MAP and risk factors associated by testing antibody-positive in sheep flocks located in the arid and hot region of Sonora, Mexico. A cross-sectional study was conducted from February 2012 to December 2014, in 43 flocks. Serum samples from 1178 individual sheep were obtained to detect antibodies against MAP by immunodiffusion in agar-gel. During blood sampling, information about animal and flock management risk factors were obtained by applying a questionnaire to the owners. Risk factors associated with seroprevalence of MAP were estimated using binary logistic regression. The true prevalence of MAP was 7.48% (95% CI 5.98, 8.98) and 53.5% of flocks had at least one seropositive animal. An animal was more likely to be seropositive if it was from a large flock (> 300 animals; OR 3.52, 95% CI 1.24, 9.99) and was born outside the farm (OR 6.24; 95% CI 2.9-1, 3.52). This is the first report of Mycobacterium avium subspecies paratuberculosis seroprevalence in sheep, in Sonora, Mexico. Large flocks and the entry of new animals to the flock were critical risk factors associated with MAP seropositivity.