Seroprevalence and spatial distribution of Neospora caninum in a population of beef cattle.

A cross-sectional serological survey for Neospora caninum was carried out in Swedish beef cattle in order to estimate the seroprevalence and investigate any geographical patterns of the infection. Blood samples were collected from 2754 animals in 2130 herds and analysed for presence of antibodies to N. caninum. The study included 18.5% of all Swedish beef herds. Spatial autocorrelation was assessed by calculating Moran's I and cluster detection was performed using LISA- and spatial scan statistics. The seroprevalence of N. caninum was 2.8% (95% CI: 2.18-3.44). Positive samples were found only in the southern half of Sweden. Moran's I was positive (I=0.045, p<0.01) and indicated global spatial autocorrelation. Using the spatial scan test based on a Bernoulli model, a cluster comprising 16 postal code areas and including 19 seropositive animals was identified. The results indicate that there is a cluster of higher risk of N. caninum (relative risk=3.95) in the southern part of Sweden, in the counties of Kronoberg and Skåne. This is the first report on the seroprevalence of N. caninum in beef cattle in Sweden.