Molecular and immunodiagnosis of bovine neosporosis in Switzerland

Cyst-forming coccidia may cause significant losses in livestock, primarily due to abortion,loss of young animals and neuromuscular diseases. Rather re cently, Neospora caninum has been recog nized as one of the major protozoal abortion-inducing parasites in cattle. The present study addressed the per formance of different diagnostic tools (in vitro-cultivation; histology; im munohistochemistry; serology; PCR) suitable for the direct or indirect dete ction of N. caninum. By PCR, Neospora-DNA was detected in 24 brains (29%) f rom 83 bovine abortion, many of these brains were simultaneously characteri zed by histopathological findings typical for a protozoal, cerebral parasit osis. The diagnostic methods were furthermore assessed using samples of dif ferent tissues and body fluids from three experimentally Neospora-infected pregnant cows and their foetuses. The diaplacental passage of N. caninum to the foetus was successful in two of the three cases. In theses two cases, PCR was positive for different foetal organs and, additionally for the abom asal and amniotic fluid. The succesfully infected cows developed anti-Neosp ora serum antibodies between 10 and 17 days post infection, foetuses remain ed serologically negative in all cases. The results obtained in the present study demonstrated the usefulness of PC R, complemented by serology, for the specific diagnosis of bovine neosporos is. Such tests may prove suitable to perform epidemiological in investigati ons. Taken together, our data indicated that prenatal neosporosis may be an important cause of infectious bovine abortion in Switzerland.