Bangladeshi man and cows
Photo credit: Lepra

About Leprosy (Hansen’s disease)

Leprosy, also known as Hansen’s disease, is preventable and curable. In fact, 95% of the world population has natural immunity.

Leprosy is caused by Mycobacterium leprae and transmitted via droplets through the nose and mouth of untreated persons affected by leprosy. After infection, it can take up to 20 years before symptoms begin to appear.

Since 1981, more than 16 million persons affected by leprosy have been treated with multi-drug therapy (MDT), donated at first by The Nippon Foundation, and since 2000 by Novartis, through the World Health Organization (WHO). Access to MDT has reduced the global number of people being treated for M. leprae infection by 99%. However, the number of people newly diagnosed with leprosy has plateaued at more than 200,000 per year for over a decade. The majority of new leprosy diagnoses occur in India, Brazil, and Indonesia, where persons affected often delay medical attention due to limited access to health services or fear of stigma and discrimination.

Leprosy has medical and social implications, forcing people to abandon professions, lose sources of income, and limit access to health services. These implications affect individuals, families, and society as a whole.

Where is leprosy found?

Communities are affected by leprosy all around the world, with most new diagnoses in India, Indonesia, and Brazil. The map below from The Leprosy Mission shows the number of new diagnoses per country, based on data from WHO.

TLM Case Detection Map

Leprosy and neglected tropical diseases

Leprosy is one of 19 neglected tropical diseases recognized by the WHO. Learn about the WHO Global Leprosy Programme’s Global Leprosy Strategy, and view the WHO LEprosy Fact Sheet for information on leprosy transmission, symptoms, and treatment.

WHO’s Leprosy Fact Sheet

Disability and stigma

Multi-drug therapy (MDT) can prevent many permanent physical effects of the disease. However, persons affected by leprosy are often challenged with physical disabilities and the social stigma and discrimination that accompanies the disease. Find answers to common questions about the medical and social implications of leprosy, and learn the language we use to talk about the disease and the people it affects.

ILEP’s Leprosy Q&AALM FAQILEP Policy for Language and ImageryIDEA: Words and Photos MatterGPZL Glossary


World Health Organization, Weekly Epidemiological Record, 1 September 2017. Vol. 92, 35 (pp. 501-520). Available at:

Smith, C. S., Noordeen, S. K., Richardus, J. H., Sansarricq, H., Cole, S. T., Soares, R. C., … & Baruaf, S. (2014). A strategy to halt leprosy transmission. The Lancet Infectious Diseases, 14(2), 96-98. Available at:

Peter Steinmann, Steven G Reed, Fareed Mirza, T Déirdre Hollingsworth, Jan Hendrik Richardus. Innovative tools and approaches to end the transmission of Mycobacterium leprae. Lancet Infect Dis 2017; 17: 298–305

World Health Organization. (2016). Strategy 2016-2020: Accelerating Towards a Leprosy-free World. WHO SEARO/Department of Control of Neglected Tropical Diseases, New Delhi. Available at:

Richardus, J. H., Nicholls, P. G., Croft, R. P., Withington, S. G., & Smith, W. C. S. (2004). Incidence of acute nerve function impairment and reactions in leprosy: a prospective cohort analysis after 5 years of follow-up. International journal of epidemiology, 33(2), 337-343. Available at:

World Health Organization, Leprosy factsheet. Available at: