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 mammary gland and supramammary lymph nodes were collected from 20 Comisana breed sheep. Milk of 14 out of 20 ewes was available for sampling. Intestine and mesenteric lymph nodes were also collected in order to confirm MAP infection. Frozen samples were used for bacteriological examination and PCR (IS900), and samples embedded in paraffin were tested by Ziehl-Neelsen staining and immunohistochemistry (PoAb anti-MAP). The MAP infection was confirmed by the detection of mycobacteria in intestine and mesenteric lymph nodes of the 20 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 supramammary lymph nodes. MAP DNA was detected by PCR in 16 samples of mammary gland, 20 of supramammary lymph nodes and 6 of milk; bacterial isolation and identification was obtained from 17 samples of mammary gland. The results 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 spread via udder and on evaluation of the sanitary risks for human health.