n.
or Hansen disease
Chronic disease of the skin and superficial nerves, caused by the bacterium Mycobacterium leprae .
In the lepromatous (cutaneous) type, grainy masses infiltrate inflamed tissue under the skin, in the lining of the upper respiratory tract, and in the testes; if this form of the disease is left untreated, the outlook is poor. The tuberculoid type, marked by spots having raised, reddish borders and patches that spread and lose feeling, may not progress or may improve. Long-term sulfa drug therapy usually helps; rehabilitation is usually also needed. Leprosy has a long history, but the disease seen today may not be the same one known in antiquity. A variety of infectious diseases that reached Europe from the East, especially with the returning Crusaders, led to the creation of leper colonies, where the ill were segregated and cared for. How leprosy spreads is still unclear; prolonged close contact with an infected person usually precedes infection. Prevention depends on recognizing cases for isolation and treatment.