Presence of Chlamydia abortus in colostrum, milk and vaginal discharge samples of sheep

32 Background: The main route of transmission of Chlamydia abortus is the ingestion of 33 the microorganism that has been eliminated in vaginal secretions, placental membranes 34 or abortions that contaminate the environment, and possibly through milk and colostrum. Elimination through vaginal secretions is well documented. However, there are no reports of the isolation and identification of C. abortus in the colostrum or milk of infected sheep, so it is important to determine whether or not the bacteria may be present in these secretions, which are the only food of lambs. Objective: Detect the presence of C. abortus in colostrum, milk and vaginal secretions of sheep with a history of reproductive 40 disorders. Methods: In order to isolate and identify C. abortus in these secretions, 41 colostrum, milk and vaginal exudate were collected from 66 sheep. The samples were 42 inoculated in mouse fibroblast cell cultures and the presence of the bacteria determined 43 by direct immunofluorescence. Results: 19 of 66 colostrum samples (28.7%), 14 of 66 44 milk samples (21.2%) and 17 of 66 vaginal swabs (25.7%) being positive. The 50 samples 45 positive for isolation and detected by immunofluorescence, together with 42 negative 46 ones, were subjected to qPCR to amplify a fragment of the omp A gene from C. abortus . 47 Thirty-eight of the 92 samples processed by this technique were positive for C. abortus . 48 Conclusion: The results of the present study demonstrated the presence of C. abortus in 49 a high proportion in colostrum, milk and vaginal secretions of infected sheep. This work 50 is the first field study in the scientific literature confirming the presence of C. abortus in 51 colostrum, which shows that the excretion of Chlamydia by lactogenesis could occur in 52 the first hours after birth. 53