Target product profile for a diagnostic test to confirm leprosy in individuals with clinical signs and symptoms

Overview

Leprosy, also known as Hansen’s disease, is a chronic infectious disease caused by Mycobacterium leprae or, in some cases, by Mycobacterium lepromatosis. The bacteria is likely transmitted via tiny droplets (aerosols) from the nose and mouth during close and frequent contact with untreated cases. In some circumstances, skin-to-skin contact has also been implicated. Close and frequent contact increase the risk of contacts developing leprosy. Stigmatization and discrimination impede the life of an individual suffering from leprosy; overcoming them is an essential part of leprosy control. As with other neglected tropical diseases (NTDs), the occurrence of leprosy is often related to socioeconomic determinants of health.

M. leprae multiplies slowly and the incubation period of the disease averages 5 years. Symptoms may occur within 1 year but can also take up to 20 years or longer to appear. The disease mainly affects the skin, the peripheral nerves, the mucosal surfaces of the upper respiratory tract and the eyes. Leprosy is known to occur at all ages, from early infancy to advanced old age. It is curable with multidrug therapy (MDT) and treatment administered in the early stages can prevent disability. Untreated, leprosy can cause progressive and permanent damage to the skin, nerves, limbs and eyes.

Despite the available treatment, more than 200 000 new leprosy patients were diagnosed globally in 2019, with more than 120 countries reporting cases (including non-autochthonous cases); 80% of the burden is in India, Brazil and Indonesia. Early case detection is important to help contain the spread of infection and prevent disabilities.