Mycobacterium avium subspecies paratuberculosis (MAP) is the etiological agent of paratuberculosis, a chronic gastroenteritis of ruminants and has zoonotic importance. We present here a review of MAP with respect to--(i) present diagnostic techniques and important developments; and (ii) MAP strain-typing tools. A summary of the findings to date is presented, and advantages and disadvantages of each of the methods are compared and discussed.