Supranational comparison of Neospora caninum seroprevalences in cattle in Germany, The Netherlands, Spain and Sweden

Abstract

Herd, within-herd and animal prevalences for Neospora caninum in beef and dairy cattle were compared between four countries. In randomly selected herds from regions of Germany, The Netherlands, Spain and Sweden that were representative for the cattle production of these countries, all animals ≥2 years were examined serologically by enzyme-linked immunosorbent assays (ELISAs) with high test specificity (>98.0%). In a previous study, the ELISAs had been validated against each other. Single reacting animals within a herd were confirmed by immunobloting. At the time of sampling, animal (age, breed, herdtype, sex, lactation stage) and herd data (region) were collected. Considerable differences in N. caninum herd, within-herd, and overall animal prevalence estimations were observed between countries, regions, herdtype, age categories and breeds. Herd prevalences, based on confirmation of single reactors, for dairy herds were estimated to be 16% (95%CI: 10–24%) in Sweden, 49% (95%CI: 39–59%) in Germany, 63% (95%CI: 57–69%) in Spain and 76% (95%CI: 67–84%) in The Netherlands and for beef herds 41% (95%CI: 31–50%) in Germany, 46% (95%CI: 41–51%) in Spain and 61% (95%CI: 50–72%) in The Netherlands. No beef herds were examined in Sweden. The lowest animal true prevalence was estimated in dairy cattle in Sweden (0.5% (95%CI: 0.1–0.8%)) while the highest animal true prevalence was estimated for dairy cattle in Spain (16.2% (95%CI: 14.9–17.5%)). Within-herd prevalences varied greatly, with very few farms in Sweden having more than 10% seropositive animals while in Spain more than 10% of the herds had within-herd prevalences between 50 and 100%. Seropositivity was significantly associated with herdtype (beef versus dairy), age, breed and region within countries. The results of this supranational comparative study showed that the importance of N. caninum infection varied greatly within in Europe. Estimates of prevalence can be used to calculate the economic impact of N. caninum infection as well as to evaluate the effect of prevention and control strategies over time.