Diseases Home > What Causes Leprosy?
What causes leprosy? Mycobacterium leprae is responsible for the disease. This bacteria grow very slowly and mainly affect the skin, nerves, and mucous membranes. When a person becomes infected with Mycobacterium leprae, the bacteria begin to multiply within the body; symptoms often begin after three to five years. Even in severe cases, damage is limited and generally affects feet, hands, and peripheral nerves.
Mycobacterium leprae are part of the family Mycobacteriaceae, which is the same family as the bacteria that cause tuberculosis (Mycobacterium tuberculosis). Mycobacterium leprae grow slowly and mainly affect the skin, nerves, and mucous membranes. Even in severe cases of leprosy, the destruction caused by Mycobacterium leprae is limited to the:
- Peripheral nerves
- Front portion of the eyes
- Upper respiratory passages.
Most scientists believe that leprosy spreads from person to person through infected respiratory droplets. While this may be one mode of leprosy transmission, more than 50 percent of people who develop the disease have no confirmed contact with an infected person. Other factors that may play a role in a person developing leprosy include:
- The extent of exposure
- Environmental conditions.
When a person becomes infected with Mycobacterium leprae, the bacteria begin to multiply within the body. After three to five years, leprosy symptoms can begin. This period between becoming infected and the start of symptoms is called the "leprosy incubation period." In most cases, the incubation period for leprosy is typically between three and five years. However, the incubation period can range from six months to several decades.