Leprosy is a chronic disease caused by the bacillus Mycobacterium leprae. Leprosy is transmitted via droplets from the nose and mouth during close and frequent contact with untreated cases, but is not highly infectious. M. leprae multiplies very slowly with an incubation period of about 5 years, but symptoms can take as long as 20 years to appear. If left untreated, however, leprosy can cause progressive and permanent damage to the skin, nerves, limbs and eyes.
Leprosy is curable, and treatment provided in the early stages averts disability. Early diagnosis and treatment with multidrug therapy (MDT) remain the key elements in eliminating the disease as a public health concern. Leprosy can be easily treated with a 6-12-month course of multidrug therapy. Since 1995, WHO has made MDT available free of charge to all patients worldwide. This treatment provides a simple yet highly effective cure for all types of leprosy with few side-effects and low relapse rates.