Preliminary study on localization of Mycobacterium avium subsp. paratuberculosis in udder of seropositive ewes [Studio preliminare della localizzazione di Mycobacterium avium subsp. paratuberculosis nella mammella di pecore sieropositive]

In order to evaluate the presence of Mycobacterium avium subsp. paratuberculosis (MAP) in milk and mammary apparatus of seropositive ewes, samples of intestine, mammary gland, mammary and mesenteric lymph nodes, and milk were collected from 20 Comisana breed sheep for bacterial culture and PCR (IS900). Samples embedded in paraffin were tested by Ziehl-Neelsen staining and immunohistochemistry (PoAb anti- MAP).The different diagnostic methods carried out on intestine and mesenteric lymph nodes confirmed the MAP infection in all ewes. Ziehl-Neelsen staining and immunohistochemistry detected the mycobacteria respectively in 4 and 10 samples of mammary gland and in 12 and 13 samples of mammary lymph nodes. MAP DNA was detected by PCR in 16 samples of mammary gland, 20 of mammary lymph nodes and 6 of milk; bacterial culture are in progress.The results obtained demonstrated a frequent localisation of MAP in mammary gland and mainly in mammary lymph nodes. PCR has proved to be more sensitive than the other methods used and the results confirm the possibility of MAP transmission with milk. These data arouse interest in further investigations on mycobacteria excretion via udder and on evaluation of the sanitary risks for human health.