Seroprevalence of Neospora caninum infection in dairy cattle in northeastern China.

The seroprevalence of Neospora caninum infection in China's northeastern Heilongjiang Province was surveyed between 2007 and 2008. In total, 540 serum samples of dairy cattle from 9 counties were examined for antibodies to N. caninum by enzyme-linked immunosorbent assay (ELISA). The overall seroprevalence of N. caninum in dairy cattle was 13.3% (72/540). The seroprevalence of N. caninum in aborting cows (14.9%) was slightly higher than that in nonaborting cows (10.3%). Dairy cattle with 5 pregnancies had the highest seroprevalence (22.7%). However, there was no apparent association between N. caninum seropositivity and aborting age or number of pregnancies (P > 0.05). There was, however, an apparent association between N. caninum seroprevalence and animal husbandry practices, with the cattle under confinement feeding having significantly lower seroprevalence than the grazing cows (P < 0.05). The results of the present survey indicates that infection with N. caninum in dairy cattle is widespread in Heilongjiang Province, and that it appears to be an important cause of bovine abortion.