Leprosy is one of the major mycobacterial diseases caused by Mycobacterium (M.) leprae or M. lepromatosis. While there is scientific evidence for human leprosy from Iron Age, it became more prevalent during medieval times, deeply affecting society and social life. Leprosy was considered a consequence of sin and was later thought to a certain extend to be inherited. Lepers were declared legally dead and excluded from normal social life. In the 14th century, the medicalization of leprosy began. Leprosaria became the earliest hospitals in Middle Ages that were specialized for a single disease. They had their own churches, cemeteries and priests. Treatment included both medical and spiritual approaches.