Leprosy
Leprosy is a curable infectious disease, endemic in many countries, caused by the bacterium Mycobacterium leprae (M. leprae). It mainly affects the skin, peripheral nerves, mucosa of the upper respiratory tract and eyes. Untreated, it can lead to permanent disability (adapted from WHO, 2025).
Primary reference(s)
WHO, 2025. Leprosy. World Health Organization (WHO). Accessed 25 May 2025.
Annotations
Additional scientific description
Leprosy is an age-old disease and is described in the literature of ancient civilizations. It is a chronic infectious disease which is caused by a type of bacteria called Mycobacterium leprae. The disease affects the skin, the peripheral nerves, mucosa of the upper respiratory tract, and the eyes. Leprosy is curable and treatment in the early stages can prevent disability. Apart from the physical deformity, persons affected by leprosy also face stigmatization and discrimination (WHO, 2025).
During 2023, a total of 182,815 new cases were reported globally, corresponding to a new case detection rate of 22.7 per million population. The number of new cases detected globally was 5% higher than in 2022 (174,094). Globally, the number of new cases decreased by 14.6% during the decade 2014-2023. The decrease in 2014-2019 was 5.3% (WHO, 2024a).
Mycobacterium leprae multiplies very slowly with an incubation period of about five years, but symptoms can take as long as 20 years to appear. If left untreated, 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. Since 1995, WHO has made MDT available free of charge to all patients worldwide (WHO, 2022).
Laboratory diagnosis is via the identification of acid-fast bacilli in a slit-skin smear. Other tests (such as serological markers) are associated with low diagnostic accuracy (WHO, 2018).
The first breakthrough for leprosy treatment occurred in the 1940s with the development of the medicine dapsone. The duration of treatment lasted many years, often a lifetime, making compliance difficult. In the 1960s, M. leprae started to develop resistance to dapsone, the only known anti-leprosy medicine at that time. In the early 1960s, rifampicin and clofazimine were discovered and found to be effective.
In 1981, the World Health Organization (WHO) recommended multidrug therapy. The currently recommended multidrug therapy regimen consists of medicines: dapsone, rifampicin and clofazimine. This treatment lasts for six months for pauci-bacillary and 12 months for multi-bacillary cases. Multidrug therapy kills the pathogen and cures the patient. Since 1995, the WHO has provided multidrug therapy for leprosy free of cost. Free multidrug therapy was initially funded by The Nippon Foundation, and since 2000 it is donated through an agreement with Novartis until at least 2020. More than 16 million leprosy patients have been treated with multidrug therapy over the past 20 years (WHO, 2025).
The Centers for Disease Control and Prevention has published information on Hansen's Disease/Leprosy case definitions (CDC, 2021).
Metrics and numeric limits
The elimination of leprosy as a public health problem is defined as a registered prevalence of less than 1 case per 10,000 population. This was achieved globally in 2000, but pockets of higher prevalence within some countries continue to persist. Based on 184,212 cases at the end of 2018, the prevalence rate corresponds to 0.2/10,000 (WHO, 2025).
Key relevant UN convention / multilateral treaty
Convention on the rights of persons with disabilities (CRPD) (UNGA, 2007).
International Health Regulations (2005), 3rd ed. (WHO, 2016).
Drivers
Leprosy is transmitted via droplets, from the nose and mouth, during close and frequent contact with untreated cases (WHO 2023a). Leprosy is a highly variable disease, affecting different people in different ways, according to their immune response. Those at one end of the spectrum, with a high level of immunity is Paucibacillary (PB) leprosy, usually manifesting as a case of leprosy with 1 to 5 skin lesions, without demonstrated presence of bacilli in a skin smear. Those with many bacilli in the body are referred to as patients with Multibacillary (MB) defined as a case of leprosy with more than five skin lesions; or with nerve involvement (pure neuritis, or any number of skin lesions and neuritis); or with the demonstrated presence of bacilli in a slit-skin smear, irrespective of the number of skin lesions (WHO, 2025).
Impacts
Leprosy is a neglected tropical disease (NTD) which still occurs in more than 120 countries, with more than 200,000 new cases reported every year. Elimination of leprosy as a public health problem globally (defined as prevalence of less than 1 per 10,000 population) was achieved in 2000 (as per World Health Assembly resolution 44.9) and in most countries by 2010 (WHO, 2025).
The reduction in the number of new cases has been gradual. As per data from 2023, Brazil, India and Indonesia continue to report more than 10,000 new cases, while 12 other countries (Bangladesh, Democratic Republic of Congo, Ethiopia, Madagascar, Mozambique, Myanmar, Nepal, Nigeria, Philippines, Somalia, Sri Lanka and the United Republic of Tanzania) each reported 1,000–10,000 new cases. Fifty-six countries reported 0 cases and 112 reported fewer than 1,000 new cases. (WHO, 2025).
Multi-hazard context
Leprosy disproportionally affects impoverished populations with limited access to sanitation and education (Leano et al., 2019).
Stigma and discrimination against persons affected by leprosy and their families are almost as old as recorded history. Effects may include social exclusion, loss of income, reduced access to health care and education, and reduced mental well-being. Changing beliefs and prejudices is not easy. Reduction in community prejudice promotes early detection of leprosy and improves acceptance of diagnosis and adherence to treatment and self-care practices. Official processes should be in place to register and take action on reports of discriminatory behaviour. Special attention should be given to vulnerable populations including women, children, immigrants, refugees, the elderly, the homeless, residents of deprived leprosy ‘colonies’ and those living in geographically inaccessible areas (WHO SEARO, 2017).
The social, emotional and economic impacts of leprosy are arguably a greater burden than the disease itself. Persons affected by leprosy need access to mainstreamed, community-based rehabilitation services focused on mitigating the effect of impairments, enabling livelihoods and optimising inclusion in the community. Access to a country’s social entitlements and other welfare measures is also essential to reduce adverse socio-economic consequences, and to ensure appropriate care for older persons living with disabilities (WHO SEARO, 2017).
Risk Management
Case detection and treatment with MDT alone have proven insufficient to interrupt transmission. To boost the prevention of leprosy, with the consent of the index case, WHO recommends tracing household contacts along with neighbourhood and social contacts of each patient, accompanied by the administration of a single dose of rifampicin as preventive chemotherapy (WHO, 2025).
After detailed consultations with countries, experts, partners and persons affected by leprosy, WHO released the Towards Zero Leprosy: Global Leprosy (Hansen’s disease) Strategy 2021–2030, aligned to the neglected tropical diseases road map 2021–2030 (WHO SEARO, 2017). The Strategy calls for a vision of zero leprosy: zero infection and disease, zero disability, zero stigma and discrimination and the elimination of leprosy (defined as interruption of transmission) as its goal. The four strategic pillars of the Strategy include: implementing integrated, country-owned zero leprosy roadmaps in all endemic countries; scaling up leprosy prevention alongside integrated active case detection; managing leprosy and its complications and preventing new disability; and combatting stigma and ensuring human rights are respected. The Strategy also recognizes that global and national investment in research is essential to achieving zero leprosy and includes a set of key research priorities (WHO SEARO, 2017; WHO, 2025).
In 2023, WHO released technical guidance on interruption of transmission and elimination of leprosy disease. At the core of this guidance is the Leprosy Elimination Framework, which provides a clear pathway through 3 phases, i.e. interruption of transmission, elimination of leprosy disease and post-elimination surveillance, defined in terms of epidemiological milestones (WHO, 2023b).
Monitoring
WHO collects relevant epidemiological and programmatic data from countries to assess the global leprosy situation and to publish an update. Annual data on leprosy are collected by WHO through a customized application with DHIS2 software (WHO, 2024a).
References
CDC, 2021. Hansen’s Disease / Leprosy (Mycobacterium leprae) 2013 Case Definition. Centers for Disease Control and Prevention (CDC). Accessed 25 May 2025.
Leano, H.A.M., Araújo, K.M.D.F.A., Bueno, I.C., Niitsuma, E.N.A., Lana, F.C.aF., 2019. Socioeconomic factors related to leprosy: an integrative literature review. Rev Bras Enferm. 72(5):1405-1415. English, Portuguese. doi: 10.1590/0034-7167-2017-0651. PMID: 31531668. Accessed 25 May 2025.
UNGA, 2007. Convention on the rights of persons with disabilities (CRPD): resolution / adopted by the General Assembly, 24 January 2007, A/RES/61/106. United Nations General Assembly (UNGA). Accessed 25 May 2025.
WHO, 2016. International Health Regulations (2005), 3rd ed. World Health Organization (WHO). Accessed 25 May 2025.
WHO, 2018. Guidelines for the diagnosis, treatment and prevention of leprosy. World Health Organization (WHO). Accessed 25 May 2025.
WHO, 2022. Health Topic: Leprosy. World Health Organization (WHO). Accessed 9 January 2025.
WHO, 2023. Technical guidance on interruption of transmission and elimination of leprosy disease. Geneva: World Health Organization (WHO). Accessed 9 January 2025.
WHO, 2024a. Global leprosy (Hansen disease) update, 2023: Elimination of leprosy disease is possible – Time to act: Weekly Epidemiological Record. World Health Organization (WHO). Accessed 9 January 2025.
WHO, 2024b. Leprosy (Hansen’s disease). World Health Organization (WHO). Accessed 25 May 2025.
WHO, 2025. Leprosy. World Health Organization (WHO). Accessed 25 May 2025.
WHO SEARO, 2017. Towards Zero Leprosy. Global Leprosy (Hansen’s disease) Strategy 2021–2030. New Delhi Licence: CC BY-NCSA 3.0 IGO. World Health Organization. Regional Office for South-East Asia (WHO SEARO). Accessed 25 May 2025.