Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacteria Mycobacterium leprae or Mycobacterium lepromatosis. Initially, a person who is infected does not have symptoms and typically remains this way for 5 to 20 years. Infection can lead to damage of the nerves, respiratory tract, skin, and eyes. This damage may result in a lack of ability to feel pain, which can lead to the loss of parts of extremities from repeated injuries or infection due to unnoticed wounds. An infected person may also experience weakness and poor eyesight.