Abstract

AIMS: Assess the prevalence of Mycobacterium bovis bacilli in faecal samples of tuberculous cattle, to better understand the risk of environmental dissemination of bovine tuberculosis (TB) through the spreading of manure or slurry. METHODS AND RESULTS: Faecal samples were collected from 72 naturally infected cattle with visible lesions of TB that had reacted to the tuberculin skin test and 12 cattle experimentally infected with M. bovis. These were examined by microbial culture and PCR to assess the presence of M. bovis bacilli. There were no positive cultures from any naturally infected test reactor animal. A single M. bovis colony was cultured from a faecal sample from one of the experimentally infected animals. A single PCR positive result was obtained from the faecal sample of one naturally infected test reactor. CONCLUSION: The prevalence of M. bovis in the faecal samples of TB-infected cattle was extremely low. SIGNIFICANCE AND IMPACT OF STUDY: The results suggest that the risk of spreading TB through the use of slurry or manure as an agricultural fertiliser is lower than suggested in some historical literature. The results could inform a reconsideration of current risk assessments and guidelines on the disposal of manure and slurry from TB-infected herds.