Neospora caninum infection in breeder bulls: seroprevalence and comparison of serological methods used for diagnosis.

Aims: To investigate the seroprevalence of Neospora caninum infection in breeder bulls. In addition, the level of agreement of serological methods used was evaluated.

Methods: A total of 285 bulls of different ages and breeds raised for reproductive purposes in Spain were sampled for serum antibody activity to N. caninum. Sera were tested using three validated assays: the indirect fluorescent antibody test (IFAT) and two commercially available enzyme-linked immunosorbent assays (ELISA).

Results: Antibodies to N. caninum were found in 13.7% of bulls sampled by at least one of the three validated serological assays. The seroprevalence of neosporosis oscillated between 11.2 and 13.3% depending on the serological technique used. No significant associations (P > 0.05) were observed between N. caninum infection and bull breed or age. The serum antibody levels were predominantly low and close to threshold levels in all positive samples. A very good agreement was found among the serological methods used.

Conclusions: This is the first seroprevalence study of bovine neosporosis in breeder bulls and results showed a moderate presence of N. caninum chronic infections.