Most consumers of dairy products accept that pasteurization provides a guarantee that products are safe to eat and drink. However, research [1] using a new highly sensitive technology has revealed that live mycobacteria can exist in retail milk even after pasteurization and explains how this may happen. Live Mycobacterium avium subspecies paratuberculosis (MAP) - which causes Johne’s disease in cattle and has been implicated in Crohn’s disease in humans - was found in just over 10% of shop-bought pasteurized milk samples that were tested in the UK.