what causes leprosy
Leprosy Causes. Leprosy is an acquired infectious disease that can affect individuals of all ages. It is caused by the acid-fast, rod-shaped bacteria Mycobacterium leprae, which was discovered in 1873 by G.A. Hansen. 1  Because the bacterium multiplies very slowly, the signs and symptoms of leprosy may not develop until much later after exposure to M. leprae (ranging from several weeks to 20 years or more).