Vertical and Horizontal Transmission of Mycobacterium paratuberculosis
DOI:
https://doi.org/10.21423/aabppro19926420Keywords:
Mycobacterium paratuberculosis, Johne's disease, Milk sample, M. paratuberculosis, Fetal infection, direct excretionAbstract
Fetuses were obtained from 58 pregnant cows naturally infected with Mycobacterium paratuberculosis (as determined by fecal culture), but showing no clinical signs of Johne's disease. Fetal tissues (spleen, liver, kidney, ileum, mesenteric lymph node) were cultured for M. paratuberculosis. Only 5 of 58 fetuses were culture positive (8.6%). All 5 culture-positive fetuses were from asymptomatic cows shedding high numbers of organisms in the feces.
Milk samples were collected aseptically from 77 cows naturally infected with M. paratuberculosis but showing no clinical signs. Of 77 samples, 9 (11.6%) were culture positive for M. paratuberculosis. Supramammary lymph nodes were culture positive form 22 of 81 cows (27%).
Fetal infection and direct excretion of M. paratuberculosis in milk can occur in asymptomatic infected cows, but with lower frequency than cows with signs of Johne's disease.
