Lepra: Various etiologies from miasma to bacteriology and genetics

Leprosy is a chronic infectious disease caused by a close relative of Mycobacterium tuberculosis: Mycobacterium leprae. There have been various beliefs in its etiology with two main concepts emerging: anticontagion and contagion. From ancient times through the early Middle Ages, the miasmatic theory of leprosy was the main anticontagion view. The development of histopathologic and cytologic studies in the second half of the 19th century provided a starting point to explain the etiology of leprosy bacteriologically.