Leprosy diagnosis. 16th-century illustration of physicians examining skin lesions on a patient with leprosy (a leper). They are using a flask called a matula (right) to carry out analysis of the patient's urine. A treatment is being prepared at left. Leprosy is a neurological disease caused by the bacterium Mycobacterium leprae. The damage to the nerves leads to disfiguring skin lesions and deformities. Artwork published in Strasbourg in 'Feldtbuch der Wundartzney' (1540) by Hans von Gersdorff (c.1455-1529).