Seroprevalence of Neospora caninum in feral swine (Sus scrofa) in the United States.

The protozoon Neospora caninum is a major cause of abortion in cattle worldwide. Canids (Canis familiaris, Canis latrans, Canis lupus) are definitive hosts whereas many other animal species, including pigs, are intermediate hosts for the parasite. Between 2012 and 2014, serum samples from 1059 feral swine (Sus scrofa) from 29 states of the USA were tested for N. caninum antibodies, using the N. caninum agglutination test (NAT). Of these, 159 (15.0%) feral pigs from 21 states tested positive, with a range of titers of 1:25 (cut-off) (n=153), 1:200 (1), 1:400 (1), 1:800 (3) and 1:3200 (1). Results indicate widespread exposure of feral swine to N. caninum infection across the USA.