Seroprevalence of Neospora caninum and abortion in dairy cows in northern Spain

The seroprevalence of Neospora caninum infection was estimated from a sampl e of 889 cattle from 43 dairy herds in three counties in the Asturias regio n of Spain. The true prevalence of infection was estimated to be 30.6 per c ent (95 per cent confidence interval (CI) 27.6 to 33.6). Seropositivity was associated with abortion during the previous year (odds ratio (OR)=3.31, P <0.001) and was slightly higher among purchased cattle (37.6 per cent), tha n among cattle raised on the farm (29.1 per cent) (P=0.078). Seropositive c ows were more likely than seronegative cows to have had a seropositive dam (OR=2.3, P=0.011), suggesting that congenital transmission contributed to a bout 56 per cent of the infections. Herds with a true seroprevalence above 10 per cent had more dogs on the farm, than herds with a lower prevalence ( P=0.032). The ORs relating abortion to seropositivity in individual herds r anged from 0.7 to 19, indicating that some herds experienced few abortions caused by N caninum, while others experienced more abortions due to the org anism. Overall, 38.7 per cent of the abortions were estimated to have been attributable to N caninum.