Your Guide to
Neglected Tropical Diseases

Leprosy, also known as Hansen's disease, is a chronic bacterial infection caused by Mycobacterium leprae that affects the skin, nerves, and eyes and airways. The disease progresses very slowly, with symptoms typically appearing about five years after infection, though it can take much longer. Early symptoms include skin patches that are lighter or darker than normal with loss of feeling. The nerve damage means people cannot feel pain in affected areas, which can lead to unnoticed injuries and infections.

Without early treatment, leprosy can cause permanent disabilities including deformities, muscle weakness, and blindness. Despite its reputation, leprosy is not highly contagious and is completely curable with treatment. However, people with leprosy often face severe stigma and discrimination.

Leprosy spreads through respiratory droplets from the nose and mouth of untreated people during prolonged, close contact over many months. When an infected person coughs or sneezes, they release droplets containing bacteria. The disease does not spread through casual contact like shaking hands, hugging, or sharing meals.

Most people who are exposed do not get sick because the disease is not very contagious. Those at highest risk are family members or people living in close contact with untreated cases. Once treatment begins, a person stops spreading the disease and can live normally among family and friends.

Geographic scope:

• Leprosy occurs in more than 120 countries, but most cases are concentrated in just three countries: India, Brazil, and Indonesia.
• India has the most cases by far- accounting for approximately 40% of new cases. globally as of 2024.
• Brazil has the second-highest number of cases, representing most cases in the Americas.
• 55 countries reported zero cases and 117 reported fewer than 1,000 new cases as of 2024.

Population affected:

• About 170,000-180,000 new cases are reported each year worldwide.
• More than 16 million people have been successfully cured since the 1980s.
• Between 3 and 4 million people are estimated to be living with permanent disabilities caused by leprosy, including visible deformities and nerve damage, compounded by stigma and social exclusion（ Reference: Towards zero leprosy. Global leprosy (Hansen’s Disease) strategy 2021-2030） .
• About 1 in 20 new cases already has visible disabilities when diagnosed, showing the importance of early detection and treatment.

Leprosy is curable with multidrug therapy (MDT), which combines three medicines: dapsone, rifampicin, and clofazimine. Treatment lasts 6 months for less severe cases and 12 months for more severe cases.

WHO has provided MDT free to all patients worldwide since 1995, initially supported by The Nippon Foundation and later donated by Novartis. Early treatment prevents disabilities. Once treatment starts, the person quickly stops being infectious and can continue normal activities. WHO also recommends giving a single dose of rifampicin to close contacts of diagnosed cases to prevent infection. The BCG vaccine for tuberculosis may provide some protection against leprosy, though no vaccine specifically prevents leprosy.

Prevention focuses on finding and treating cases early, and reducing stigma so people seek care promptly. Education helps communities understand that leprosy is not highly contagious, does not spread through casual contact, and is completely curable.