Increased risk of abortion following Neospora caninum abortion outbreaks: A retrospective and prospective cohort study in four dairy herds.

摘要

The results of a cohort study of 4 dairy herds that had outbreaks of abortions associated with Neospora caninum infection are reported. In 50 of 51 fetuses submitted during the first 3 weeks of the outbreak, characteristic histological lesions compatible with N. caninum infection were seen. Diagnosis of infection was confirmed by immunohistochemistry in 40 fetuses (78%). No other abortifacients were detected. A prospective study showed that cows aborting during the outbreak (cohort 1) and N. caninum seropositive non-aborting cows (cohort 2) had a 2- to 3-fold increased risk of abortion compared with N. caninum seronegative cows (cohort 3). A retrospective examination showed that cows in cohort 2 had an increased risk of abortion (9.8%) than thosein cohorts 1 and 2 (1.8 and 2.3% respectively) before the outbreak, indicating that cohort 2 animals were infected with N. caninum prior to the outbreak.