Diseases Home > Important Information on Leprosy
There is a limited form of leprosy called tuberculoid or paucibacillary (few bacilli) and a more generalized form called lepromatous or multibacillary (many bacilli).
Despite first discovering Mycobacterium leprae in 1873, research scientists still do not completely understand how the disease is spread.
Most scientists believe that it spreads from person to person through infected respiratory droplets. While this may be one mode of transmission, over half of the people who develop leprosy have no confirmed contact with an infected person. Other factors that may play a role in a person developing the condition include:
- The extent of exposure
- Environmental conditions.
(Click How Is Leprosy Spread? for more information.)
When a person becomes infected with the bacteria that cause the disease, the bacteria begin to multiply within the body. After three to five years, symptoms can begin. This period between becoming infected and the start of symptoms is called the "leprosy incubation period." Although the incubation period for leprosy is typically between three and five years, it can range from six months to several decades.
Leprosy usually affects the skin and peripheral nerves. However, once a person starts experiencing symptoms, they can range in type and severity. The symptoms will also vary based on the form of leprosy that a person has (tuberculoid leprosy versus lepromatous leprosy).
(Click Symptoms of Leprosy to read about specific symptoms of the disease.)