Prevalence of antibodies to Neospora caninum in wild animals.

Antibodies to Neospora caninum were determined in several species of wild animals in the United States by the Neospora agglutination test (NAT). Antibodies (NAT 1:40 or higher) were found in 5 of 249 bison (Bison bison), 5 of 160 caribou (Rangifer tarandus), 4 of 162 moose (Alces alces), 4 of 122 wolves (Canis lupus), and 1 of 224 musk ox (Ovibos moschatus) but not in 197 black bears (Ursus americanus). To our knowledge, this is the first report of antibodies to N. caninum in bison and caribou. The total absence of N. caninum antibodies in black bears indicates that bears are not a host for N. caninum and that there is no cross-reactivity between the NAT and the modified agglutination test (MAT) for Toxoplasma gondii, because more than 80% of black bears in eastern United States have MAT antibodies at a 1:25 serum solution.