Serological study of Neospora caninum in pregnant dairy cattle in Tehran, Iran

Seven hundred and sixty-eight blood samples of pregnant cattle from four Holstein dairy herds that are farmed in the vicinity of Tehran were used to evaluate the seroprevalence of Neospora caninum infection by enzyme-linked immunosorbent assay (ELISA). Two hundred and ninety-eight of the 768 blood samples (38.8%) were positive for this infection. The prevalence of infection in the herds varied from 18.7% to 65.1%. The abortion rate in seropositive and seronegative animals was 20.67% and 10.11%, respectively. Thus, the risk of abortion was approximately double the rate in seropositive cows (p<0.0005). There was a high correlation between the infection rate and the age in one herd. In other three herds, no significant correlation was found between infection rate and age. This is the first extended study with regards to the rate of Neospora caninum infection in pregnant cattle in the vicinity of Tehran.