Factors affecting the risk of infection with pseudorabies virus in Illinois swine herds

A case-control study of pseudorabies virus (PRV) infection in Illinois swine herds was conducted to identify risk factors associated with PRV infection. Factors identified as being associated with increased risk of PRV infection included percentage of herd in total confinement (adjusted OR (aOR) = 19.7, 95% confidence interval (CI): 3.3-117.2) and having two or more PRV positive herds in the township (aOR=3.2, 95% CI: 1.0-10.2). A protective factor identified in the study included using one's own vehicle to transport pigs to market rather than hiring truckers (aOR=0.2, 95% CI: 0.07-0.6). A protective factor for producers who used their own vehicle for transporting pigs was cleaning the truck after off-site trips (aOR = 0.09, 95% CI: 0.03-0.2). Management factors which can be most easily altered by producers who wish to prevent PRV infection in their herd include purchasing one's own vehicle for transport of pigs, and cleaning out this vehicle carefully after off-site visits. Total confinement herds arid herds in areas where PRV is endemic appear to be at higher risk of becoming infected with PRV, and managers should be especially aware of herd security measures.