Leprosy is a chronic infectious disease. It mainly affects the skin, the peripheral nerves, mucosa of the upper respiratory tract, and also the eyes. Leprosy is curable with multidrug therapy.

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Leprosy

Fact sheet
Updated October 2016

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Key facts

• Leprosy is a chronic disease caused by a slow multiplying bacillus, Mycobacterium leprae.
• M. leprae multiplies slowly and the incubation period of the disease is about 5 years. Symptoms can take as long as 20 years to appear.
• The disease mainly affects the skin, the peripheral nerves, mucosa of the upper respiratory tract, and also the eyes.
• Leprosy is curable with multidrug therapy (MDT).
• Although not highly infectious, leprosy is transmitted via droplets, from the nose and mouth, during close and frequent contacts with untreated cases.
• Untreated, leprosy can cause progressive and permanent damage to the skin, nerves, limbs and eyes.
• Official figures from 138 countries from 6 WHO regions show the global registered prevalence of leprosy to be at 176 176 cases at the end of 2015. During the same year, 211 973 new cases were reported.

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Introduction

Leprosy is a chronic infectious disease caused by Mycobacterium leprae, an acid-fast, rod-shaped bacillus. The disease mainly affects the skin, the peripheral nerves, mucosa of the upper respiratory tract, and the eyes.

Leprosy is curable and treatment provided in the early stages averts disability.

Multidrug therapy (MDT) treatment has been made available by WHO free of charge to all patients worldwide since 1995. It provides a simple yet highly effective cure for all types of leprosy.

Elimination of leprosy as public health problem (with a prevalence less than 1 case per 10 000 persons) was achieved globally in the year 2000. More than 16 million leprosy patients have been treated with MDT over the past 20 years.

Leprosy today

Leprosy control has improved significantly due to national and subnational campaigns in most endemic countries. Integration of basic leprosy services into general health services has made diagnosis and treatment of the disease more accessible.

Detection of all cases in a community and completion of MDT treatment were the basic tenets of the “Enhanced Global Strategy for Further Reducing Disease Burden Due to Leprosy” (2011–2015).

In 2016 WHO has launched a new global strategy – “The Global Leprosy Strategy 2016–2020: Accelerating towards a leprosy-free world” – which aims to reinvigorate efforts for leprosy control and to avoid disabilities, especially among children affected by the disease in endemic countries.

• The Global Leprosy Strategy 2016–2020: Accelerating towards a leprosy-free world

This strategy emphasizes the need to sustain expertise and increase the number of skilled leprosy staff, to improve the participation of affected persons in leprosy services, and to reduce visible deformities – also called grade-2 disabilities (G2D) – as well as stigma associated with the disease. The strategy also calls for renewed political commitment and enhanced coordination between partners, and highlights the importance of research and improved data collection and analysis.

According to official reports received from 138 countries from all WHO regions, the global registered prevalence of leprosy at the end of 2015 was 176 176 cases (0.2 cases per 10 000 people)1. The number of new cases reported globally in 2015 was 211 973 (2.9 new cases per 100 000 people). In 2014, 213 899 new cases were reported, and in 2013, 215 656 new cases.

The number of new cases indicates the degree of continued transmission of infection. Global statistics show that 199 992 (94%) of new leprosy cases were reported from 14 countries reporting more than 1000 new cases each and only 6% of new cases were reported from the rest of the world.

Pockets of high endemicity still remain in some areas of many countries, including countries reporting less than 1000 new cases. Some of these areas show very high notification rates for new cases and may still witness intense transmission.

Brief history of the disease and treatment

Leprosy was recognized in the ancient civilizations of China, Egypt and India. Throughout history, people afflicted have often been ostracized by their communities and families.

Although leprosy was managed differently in the past, the first breakthrough occurred in the 1940s with the development of the drug dapsone. The duration of the treatment was many years, often a lifetime, making it difficult for patients to adhere to it. In the 1960s, M. leprae started to develop resistance to dapsone, the world’s only known anti-leprosy drug at that time. In the early 1960s, rifampicin and clofazimin were discovered and subsequently added to the treatment regimen, which was later labelled as multidrug therapy (MDT).

In 1981, a WHO Study Group recommended MDT. MDT consists of 2 or 3 drugs: dapsone and rifampicin for all patients, with clofazimine added for multibacillary disease. This drug combination kills the pathogen and cures the patient.

Since 1995, WHO has provided free MDT for all leprosy patients in the world, initially through the drug fund provided by The Nippon Foundation, and since 2000 through a donation agreement with Novartis.

Elimination of leprosy as a public health problem

In 1991 the World Health Assembly passed a resolution to “eliminate” leprosy as a public health problem by the year 2000. Elimination of leprosy is defined as a registered prevalence rate of less than 1 case per 10 000 persons. The target was achieved on time.

The widespread use of MDT and the reduction in duration of treatment dramatically contributed to this reduction:

• Over the past 20 years, more than 16 million leprosy patients have been treated.
• The prevalence rate of the disease has dropped by 99%: from 21.1 per 10 000 in 1983 to persons to 0.24 per 10 000 in 2014.
• A dramatic decrease has been achieved in the global disease burden: from 5.2 million people with leprosy in 1985 to 805 000 in 1995, 753 000 in 1999 and 175 554 people with leprosy at the end of 2014.
• With the exception of few small countries (with populations of less than 1 million), leprosy has been eliminated from all countries.
• So far, there has been no resistance to antileprosy treatment when used as MDT, even if sporadic cases of resistance to a single drug are observed. Vigilance is maintained though a global sentinel surveillance mechanism.
• Efforts currently focus on promoting early detection of cases to reduce disease burden (in particular disabilities) and to interrupt transmission. This will ultimately contribute to eliminating leprosy at sub-national levels.

Actions and resources required

In order to reach all patients, leprosy treatment needs to be optimally integrated into general health services. Moreover, political commitment needs to be sustained in all countries even after reaching elimination. Partners in leprosy elimination also need to ensure that human and financial resources continue to be available.

The age-old stigma associated with the disease remains an obstacle to self-reporting and early treatment. The image of leprosy must be changed at the global, national and local levels. A new environment, in which patients will not hesitate to come forward for diagnosis and treatment at any health facility, must be created ensuring no discrimination and promoting inclusion.

WHO response

In order to reinvigorate efforts for leprosy control WHO has developed the “Global Leprosy Strategy 2016‒2020”, which is structured around the following 3 core pillars:

Pillar I: Strengthen government ownership, coordination and partnership

Key activities of Pillar I include:

• Ensuring political commitment and adequate resources for leprosy programmes.
• Contributing to universal health coverage with a special focus on children, women and underserved populations including migrants and displaced people.
• Promoting partnerships with state and non-state actors and promote intersectoral collaboration and partnerships at the international level and within countries.
• Facilitating and conducting basic and operational research in all aspects of leprosy and maximize the evidence base to inform policies, strategies and activities.
• Strengthening surveillance and health information systems for programme monitoring and evaluation (including geographical information systems).

Pillar II: Stop leprosy and its complications

Key activities of Pillar II include:

• Strengthening patient and community awareness of leprosy.
• Promoting early case detection through active case-finding (such as campaigns) in areas of higher endemicity and contact management.
• Ensuring prompt start of and adherence to treatment, including working towards improved treatment regimens.
• Improving prevention and management of disabilities.
• Strengthening surveillance for antimicrobial resistance including laboratory network.
• Promoting innovative approaches for training, referrals and sustaining expertise in leprosy, such as e-health.
• Promoting interventions for the prevention of infection and disease.

Pillar III: Stop discrimination and promote inclusion

Key activities of Pillar III include:

• Promoting societal inclusion by addressing all forms of discrimination and stigma.
• Empowering persons affected by leprosy and strengthening their capacity to participate actively in leprosy services.
• Involving communities in action for improvement of leprosy services.
• Promoting coalition-building among persons affected by leprosy and encouraging the integration of these coalitions and or their members with other community-based organizations.
• Promoting access to social and financial support services, for example to facilitate income generation, for persons affected by leprosy and their families.
• Supporting community-based rehabilitation for people with leprosy-related disabilities.
• Working towards abolishing discriminatory laws and promoting policies facilitating inclusion of persons affected by leprosy.

Targets of the strategy

The targets of the new global strategy to be met by 2020 are:

• Zero disabilities among new paediatric patients.
• A grade-2 disability rate of less than 1 case per 1 million people.
• Zero countries with legislation allowing discrimination on basis of leprosy.

Sustained and committed efforts by the national programmes along with continued support from national and international partners have led to a decline in the global burden of leprosy. Increased empowerment of people affected by the disease, together with their greater involvement in services and the community, will bring us closer to a world without leprosy.

1Based on population of countries that reported leprosy to WHO; not the total world population.