Low rate of detectable in utero transmission of Mycobacterium avium subspecies paratuberculosis in a dairy herd with a low prevalence of Johne's disease

In an effort to correlate the likelihood of in utero transmission of Mycobacterium avium subsp. paratuberculosis (MAP), the causal organism of Johne's disease, with the test status of the dam, tissues from neonatal calves borne to known test status cows were cultured for the presence of MAP. Tissues from a single calf borne to a test-positive cow shedding large numbers of organisms in the feces were positive for MAP. The detected overall transmission rate was approximately 2% (1/49), and the detected transmission rate in cows that were fecal culture positive and serum enzyme-linked immunosorbent assay suspect or positive was approximately 4.3% (1/23).