Leprosy, also known as Hansen's disease, is a highly contagious infection caused by a bacterium. It primarily affects the skin, mucous membranes, and nerves, but can affect other areas of the body. Scientists are still not quite sure how the disease is spread, especially since over half of the people who develop leprosy have no confirmed contact with an infected person.
There are two different types of leprosy -- tuberculoid and lepromatous -- with lepromatous being the more generalized form. Today, treatment consists of antibiotics and supportive care and can last for up to two years.
(Click Leprosy to learn more about this disease, including possible symptoms, how it is diagnosed, conditions that share similar symptoms, and more.)