Leprosy, also known as Hansen's disease, is a devastating chronic infectious disease caused by Mycobacterium leprae and Mycobacterium lepromatus. The disease predominantly affects the skin and peripheral nerves. Left untreated, it may cause progressive and permanent disabilities.

The bacteria are transmitted via droplets from the nose and mouth during close, prolonged and frequent contacts with untreated cases. Leprosy is curable with Multiple Drug Therapy (MDT). The patient stops transmitting the disease when they begin treatment.