[Diagnosis and epidemiology of Neospora caninum-associated abortions in cattle]

Abstract

Neospora caninum, a recently discovered protozoan parasite closely related to Toxoplasma gondii, has world-wide been recognized as an important cause of bovine abortion. N. caninum possesses a wide host range. The dog can be a definitive host for N. caninum. In cattle, the infection is transmitted transplacentally with high efficiency, while the majority of congenitally infected calves is clinically normal at birth and thereafter. Whether horizontal transmission occurs in cattle and whether this potential mode of transmission has epidemiological significance, remains to be elucidated. N. caninum-associated abortions can occur in epidemic or endemic form in a herd. The clinical symptoms of bovine neosporosis are confined to the occurrence of abortion, stillbirth and weak calves. Multifocal nonsuppurative encephalitis represents the most frequent pathohistological finding in N. caninum-associated abortions. The causative agent can be demonstrated by immunohistochemistry or polymerase chain reaction. Serological techniques can be used for indirect diagnosis. On the basis of the available diagnostic methods and the present knowledge about the epidemiology of the infection proposals are made regarding diagnosis, epidemiological assessment and prophylaxis of N. caninum-associated abortion problems in cattle herds.