Apparent Prevalence of Swine Brucellosis in Feral Swine in the United States

Samples were collected in 35 states as part of a national monitoring system to detect multiple diseases in feral swine (Sus scrofa). During March 2009 through December 2010, we collected serum samples from 4,479 feral swine from 13 states, and 159 animals tested were seropositive for brucellosis. No difference in likelihood of infection was found between males and females, but adults were more likely than sub-adults or juveniles to be exposed to brucellosis. Feral swine sampled during winter months also were more likely to be seropositive than animals sampled during other seasons. Apparent prevalence varied among states, and seropositive animals often were clustered in specific counties within a state. We recommend improved diagnostics and stricter regulations on movement of feral swine both intra- and inter-state to minimize further spread of the disease and to decrease the risk of reintroduction of brucellosis into livestock