MOLECULAR AND IMMUNODIAGNOSTIC INVESTIGATIONS ON BOVINE NEOSPOROSIS IN SWITZERLAND

Neospora caninum has gained considerable attention through its role in the aetiology of bovine abortion. Due to its close phylogenetic relat ionship with Toxoplasma gondii, respective unequivocal differential di agnosis deserves special consideration. In order to evaluate the diagn ostic performance of molecular and immunodiagnostic techniques and to provide insights into the epidemiological significance of bovine neosp orosis in Switzerland, we conducted a study on 83 cases of bovine abor tion: of these, 24 (29%) foetal brains were positive by Neospora-PCR, six of these foetuses were simultaneously seropositive in Neospora-IFA T and/or somatic antigen-ELISA. Conversely, four (5%) foetal brains we re considered positive by Toxoplasma-PCR, two Of which were also serop ositive in the Toxoplasma-P30-ELISA and/or direct agglutination test. The seroprevalence in 1689 cattle sera obtained from 113 dairy farms w as 11.5% (95% confidence interval: 9.2-13.8) by Neospora-somatic antig en-ELISA and 10.7% (95% confidence interval: 8.3-12.6) by Toxoplasma-P 30-ELISA. From the same samples, 1.1%, less than statistically expecte d, were positive in both ELISA. Within selected groups of cow-calf far ms, the seroprevalence determined using the Neospora-somatic antigen-E LISA was 14% (95% confidence interval: 5.0-23.0) for dams and 15% (95% confidence interval: 3.0-28.0) for offspring calves. Seroprevalences determined by Toxoplasma-P30-ELISA were 8% (95% confidence interval: 4 .0-12.0) for dams and 3% (95% confidence interval: 0.3-6.0) for calves . None of the sera gave a positive reaction in both ELISA. Our data in dicated that prenatal neosporosis appears as an important cause of bov ine abortion in Switzerland. (C) 1998 Australian Society for Parasitol ogy. Published by Elsevier Science Ltd.