Information on Leprosy (Hansen's Disease)

What is Leprosy?
Leprosy is a chronic disease caused by a bacillus, Mycobacterium leprae. M. leprae multiplies very slowly and the incubation period of the disease is about five years. However, symptoms can take as long as 20 years to appear.

What are the symptoms?
Leprosy mainly affects the skin and nerves. If untreated, there can be progressive and permanent damage to the skin, nerves, limbs and eyes. Symptoms vary from asymptomatic (no symptoms) infections through to severe disfiguring disease. Following infection, skin lesions may appear and heal spontaneously. Infection slowly affects the skin, nerves and mucous membranes. As the disease progresses (usually over a period of several years) skin lesions may increase in number or spread. These lesions range from white patches - usually with loss of skin sensitivity - to extensive skin thickening and folding. Lesions of the nerves can lead to loss of sensation and to muscle weakness and atrophy, and unnoticed burns and ulcers - especially on the hands and feet - resulting in deformities.

How is leprosy transmitted?
Leprosy is not highly infectious. Transmission is thought to be human-to-human, via nasal discharge and droplets from the respiratory tract of untreated patients with severe disease, although it may also occur via skin contact. Humans seem to be the only natural host of M. leprae. The only exception is the 9-banded armadillo found in parts of Central America, which has been used to provide a source of parasite material for research purposes.

Can leprosy be treated?
Leprosy is a curable disease and treatment provided in the early stages averts disability. Treated patients are generally cured within six to 12 months. Patients are no longer infectious to others after the first dose of treatment. In other words, transmission of leprosy is interrupted. No drug resistance has been detected. There are virtually no recurrences of the disease after treatment is completed.

How is leprosy diagnosed?
With minimal training, leprosy can be easily diagnosed on clinical signs alone.

How can leprosy be prevented?
Avoiding contact with persons with leprosy and completing treatment regimens as directed can help limit and prevent the transmission of leprosy.

Source: World Health Organization, July 5, 2006