EVALUATION OF PROCEDURES FOR THE DIAGNOSIS OF BRUCELLA OVIS INFECTION IN RAMS

Abstract

Procedures for the diagnosis of B. ovis infection in rams were evaluated by examining 10 rams artificially infected by preputial inoculation. Observations were undertaken at weekly intervals for 1 yr to follow changes in clinical, bacteriological and serological findings. Clinical lesions were detected in 1 ram 3 wk after inoculation and in all rams by 8 wk; lesions were undetectable in 3 rams at the completion of the trial. The presence of inflammatory cells in semen samples was the earliest indication of infection, being demonstrated in 2 rams at 2 wk and in all rams by 8 wk; subsequently 86% of samples were positive. B. ovis was detected in semen smears from 3 rams at 4 wk but only once in all rams (at 27 wk); overall, 52% of semen smears were positive from 4 wk onwards. B. ovis was cultured from semen of 5 rams after 4 wk and from all rams at 5 wk; thereafter 97% of samples were positive. All rams developed significant titers to the CFT [complement fixation test] by 2-9 wk; thereafter the CFT was a reliable indication of infection in 6 rams, highly suggestive in 3 and unreliable in 1. By 8-10 wk, all rams developed significant titers to the IHA [indirect hemagglutination assay] which were then maintained in all rams for the remainder of the trial.