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Leprosy - Medical

Leprosy or Hansen's disease (HD) 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 infection; infection results in tissue loss, so fingers and toes become shortened and deformed as the cartilage is absorbed into the body.

Although the mode of transmission of Hansen's disease remains uncertain, most investigators think that M. leprae is usually spread from person to person in respiratory droplets. The minimum incubation period reported is as short as a few weeks and this are based on the very occasional occurrence of leprosy among young infants. The maximum incubation period reported is as long as 30 years, or over, as observed among war veterans known to have been exposed for short periods in endemic areas but otherwise living in non-endemic areas. It is generally agreed that the average incubation period is between three and five years. Leprosy is now known to be neither sexually transmitted nor highly infectious after treatment. Approximately 95% of people are naturally immune and sufferers are no longer infectious after as little as 2 weeks of treatment.

Hansen's disease (HD) or Leprosy may also be divided into the following types:

Tuberculoid leprosy:

Tuberculoid leprosy is a skin condition characterized by solitary skin lesions that are asymmetrically distributed.

Borderline tuberculoid leprosy:

Borderline tuberculoid leprosy is a cutaneous condition similar to tuberculoid leprosy except the skin lesions are smaller and more numerous.

Borderline leprosy:

Borderline leprosy is a cutaneous skin condition with numerous skin lesions that are red irregularly shaped plaques.

Borderline lepromatous leprosy:

Borderline lepromatous leprosy is a skin condition with numerous, symmetrical skin lesions.

Lepromatous leprosy:

Lepromatous leprosy is a skin condition consisting of pale macules.

Histoid leprosy:

Histoid leprosy is a skin condition, a rare form of multibacillary leprosy.