Cause of Leprosy

An infection with Mycobacterium leprae is the cause of leprosy. Most scientists believe that the bacteria is spread from person to person through infected respiratory droplets. However, over half of those who develop leprosy have no confirmed contact with an infected person. Other factors that may play a role in the cause of leprosy include genetics, the extent of exposure, and environmental conditions.

Leprosy Facts

Cause of Leprosy: An Overview

The cause of leprosy is an infection with the bacteria Mycobacterium leprae.

Mycobacterium Leprae as the Cause of Leprosy

Mycobacterium leprae are part of the family Mycobacteriaceae. This 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:

Skin
Peripheral nerves
Front portion of the eyes
Upper respiratory passages
Testes
Hands
Feet.

Most scientists believe that leprosy spreads from person to person through infected respiratory droplets. While this may be one mode of leprosy transmission, over half of the 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:

Genetics
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, symptoms of leprosy can begin. This period between becoming infected and the start of symptoms is the "leprosy incubation period." Although the incubation period is typically between three and five years, it can range from six months to several decades.