Leprosy (Hansen’s disease) is caused by the bacillus Mycobacterium leprae. M.leprae multiplies very slowly, often inside the Schwann cells of the peripheral nervous system. The incubation period of the disease is often five years or more and symptoms can take as long as 20 years to appear. More than 200,000 new cases per year are reported globally, with a majority of the cases found in low-income communities in India, Brazil and Indonesia. The disease mainly affects the skin, the peripheral nerves, mucosa of the upper respiratory tract and the eyes. Leprosy is curable and early treatment with MDT usually prevents disability. When left untreated the disease can cause progressive and permanent damage to the skin, nerves, limbs and eyes. Once peripheral nerves are affected, loss of sensation can occur in eyes, hands or feet. As a result, injuries may go unnoticed (i.e. burns or cuts), become infected and lead to permanent impairments, including blindness, shortening of fingers and toes, contractures of fingers and toes and weakness or paralysis of hands and feet. Treatment halts the progression of the disease itself, but it cannot reverse these impairments. New nerve damage may even occur after completing leprosy treatment, due to immunological reactions to the bacterial antigen, which is cleared from the body only very slowly. While contractures of fingers and paralysis of hands or feet may be restored with reconstructive surgery, any loss of feeling in hands and feet is permanent, unless treated very early. This means that persons with nerve impairment can easily injure themselves, which in turn may lead to the above secondary impairments. The total number of individuals who live with leprosy-related chronic disfigurement and physical disabilities is estimated to be between one and two million. Even worse than the physical impairments is social exclusion due to leprosy-related stigma, which is common in most endemic countries. This leads to many forms of discrimination and human rights abuses. It is also often internalized, leading people to isolate themselves due to fear of disclosure, rejection, negative impact on their family, etc.
The above has caused leprosy to have a frightening image in history and human memory, one of mutilation, disability and social exclusion. New preventative measures, effective treatment and interventions aimed at reducing stigma and social inclusion of those affected, such as rehabilitation, are hoped to contribute to a more positive image of leprosy and to its eventual elimination.