Presence of Mycobacterium avium subspecies paratuberculosis, in goats milk, natural rennet and fresh cheese from San Luis Potosi, Mexico

Mycobacterium avium subspecies paratuberculosis (Map) is the etiological agent of paratuberculosis, which is one of the chronic diseases that cause financial losses in livestock production. Map can be present in cheese and other dairy products, especially those made with unpasteurized milk. Contamination of the food supply chain exposes humans to the bacteria, making the disease an important zoonosis of public health significance and a one-health emergency. The purpose of the study was to determine the presence of Map in raw goat milk, natural rennet, and artisanal fresh cheese. A total of 18 milk samples were collected directly from the bulking tank, 23 from fresh cheese, and 10 from milk rennet from five municipalities in the State of San Luis Potosi, Mexico. Samples were analyzed through bacteriological culture and IS900 PCR-n. Statistical analysis was carried out in STATA® 7.0, analyzing frequencies and the Kappa test to determine the concordance index between bacteriological culture and IS900 PCR-n results. Map was isolated from four milk samples (n=4/18, 22%), one from cheese (n=1/23, 4.3%), while none were obtained from rennet samples. IS900 PCR-n detected 22 positive samples: 6/18 (33.3%) in milk, 8/10 (80%) in rennet and 8/23 (34.74%) in cheese. Concordance between IS900 PCR-n and bacteriological culture in milk samples was high (0.7273) but low in cheese samples (0.0707). Map was detected in milk and artisanal cheese, although it is noteworthy that Map genomic material was detected in 80% of rennet samples analyzed with PCR. Quality control of milk, rennet, and all the inputs used for making cheese is necessary. Key words:  Paratuberculosis, map, fresh milk, cheese, rennet, goats