Leprosy or
Hansen's disease is a
chronic disease caused by the
bacteria Mycobacterium leprae and
Mycobacterium lepromatosis.
Named after
physician Gerhard Armauer Hansen, leprosy is primarily a
granulomatous disease of the
peripheral nerves and
mucosa of the
upper respiratory tract; skin lesions are the primary external sign.
Left untreated, leprosy can be progressive, causing permanent damage to the skin, nerves, limbs and eyes. Contrary to folklore, leprosy does not cause body parts to fall off, although they can become numb or diseased as a result of secondary infections; these occur as a result of the body's defenses being compromised by the primary disease.
Secondary infections, in turn, can result in tissue loss causing fingers and toes to become shortened and deformed, as cartilage is absorbed into the body.