Aetiology of bovine abortion in Switzerland from 1986 to 1995--a retrospective study with emphasis on detection of Neospora caninum and Toxoplasma gondii by PCR.

In a retrospective study, covering the period from 1986 to 1995, tissues of aborted fetuses were re-examined. A total of 347 cases were tested immunohistochemically, among them samples of 223 brains were examined for Neospora caninum, Toxoplasma gondii and Bovine Virus Diarrhoea Virus (BVDV), and 249 placentae for Chlamydiaceae. Two real-time PCR assays, one for N. caninum, and one for T. gondii, were developed. These potential abortion-inducing agents were detected - and confirmed by PCR, except for BVDV - in 16.1% (N. caninum), 0% (T. gondii), 9.9% (BVDV) and 0.8% (Chlamydiales) of the cases examined. Immunohistochemistry proved to be inadequate for the detection of the protozoal epitopes, whereas it was confirmed as a very useful tool for the detection of BVDV. In abortion material, PCR is considered to be more suitable for the detection of protozoa and Chlamydophila abortus, an adequate sampling presupposed.