The detection of Mycobacterium bovis (M. bovis) in environmental samples with precision is imperative to control bovine tuberculosis (bTB) infections at the herd level, as residual M. bovis remains one of the major causes of recurring infections. In this study, a nested PCR method for the detection of M. bovis in environmental samples was applied to identify potential environmental reservoirs of the bacterium. A set of 200 environmental samples (167 fecal samples and 33 water samples) from 39 herds with a history of bTB outbreak was analyzed using a nested PCR method to detect residual M. bovis. Amplicon libraries of the IS6110 target gene fragment were amplified from M. bovis DNA using two established primer sets. A positive nested PCR result was observed in 69.5% of fecal samples and 66.7% of water samples, thus showing that residual M. bovis was present in the environmental samples of bTB-positive herds in a high proportion. This study is the first to demonstrate high levels of M. bovis DNA in environmental samples and to show that environmental reservoirs of this pathogen contribute to recurring outbreaks of bTB. Environmental monitoring of herds in which bTB outbreaks have occurred with high sensitivity and specificity is expected to help prevent the recurrence of potential bTB disease and improve the herd environment.

The aim of the present study was to evaluate the use of an immunochromatographic test (ICT) strip using recombinant MPB70 (rMPB70) protein as a complementary tool for the diagnosis of naturally occurring tuberculosis in cattle. The study was performed on 249 cattle from populations known to be free from Mycobacterium bovis (M. bovis) and 119 cattle with M. bovis infection, confirmed postmortem. Compared to reference standards (culture isolation and/or visible lesion), the sensitivity of ICT was 94.12% (95% CI: 89.89∼98.35%) while the specificity was 96.80% (95% CI; 94.62∼96.82%). The findings indicate that the ICT strip is efficient for diagnosing bovine tuberculosis in cattle from Korea.