Disease Fact Sheet Series:

What is leprosy?
Leprosy is a bacterial disease of the skin and nervous system caused by Mycobacterium leprae. The two main types of leprosy are called lepromatous and tuberculoid. Tuberculoid leprosy is not related to tuberculosis.

Who gets leprosy?
Leprosy is usually found in South Asia, Southeast Asia, tropical Africa and some areas of Latin America. Although it is occasionally found in the southern part of the United States, most persons diagnosed with leprosy in this country are immigrants or refugees who were infected in their native countries.

What are the symptoms of leprosy?
In lepromatous leprosy, the skin lesions are many and widespread. Infection in the nose may cause crusting, bleeding and blockage; infection in the eye may cause inflammation of the iris and cornea. In tuberculoid leprosy, the skin lesions are fewer and have little or no feeling. There may also be numbness in the hands, feet or other parts of the body. Lepromatous leprosy is much more contagious than tuberculoid leprosy.

How soon after exposure do symptoms appear?
The range is from 9 months to 20 years. It usually takes 4 years from the time of exposure for symptoms of tuberculoid leprosy to appear and 8 years for symptoms of lepromatous leprosy to appear.

How is leprosy spread?
Although not clearly understood, Leprosy is thought to spread through prolonged close contact (as may occur in a household) with an untreated lepromatous patient. The bacteria enter the air from the patient's nose (by nose blowing, for example) and probably spread to others by being breathed in or coming into contact with broken skin. Untreated mothers may pass the infection to their unborn children.

When and for how long is a person able to spread leprosy?
Usually, after three months of treatment with dapsone or clofazimine, or after three days of treatment with rifampin, a person will no longer be infectious to others. No restrictions in employment or school attendance are indicated for persons whose disease is determined to be non-infectious.

How can leprosy be prevented?
Household contacts of persons with leprosy, especially children, should be examined yearly for at least five years after their last contact with an infectious person. Household contacts of patients with lepromatous leprosy who are less than 25 years old may be considered for preventive treatment.

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Last Revised: June 22, 2011