Journal of the American Veterinary Medical Association 194 10 1423 1426 UNITED STATES

Abstract

In utero transmission of Mycobacterium paratuberculosis, the causative agent of paratuberculosis in cattle, has been suggested. Tissue specimens were obtained at a packing plant from pregnant dairy cows and their fetuses and from cows with clinical signs of paratuberculosis and from their fetuses. Specimens were processed according to methods described for isolating M paratuberculosis from bovine tissues and were incubated on Herrold egg yolk medium for 16 weeks. Presumed positive specimens were confirmed to be M paratuberculosis, using acid-fast staining and subculturing. Of 407 lymph nodes from cows, 34 (8.4%) were culture positive for M paratuberculosis; 9 of 34 (26.4%) of these culture-positive cows had fetuses from which specimens were also culture positive. The results estimated the risk of fetal infection with M paratuberculosis to be 26.4% (95% confidence interval between 11.3 and 40.7%)