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Leprosy

Fact sheet
Updated February 2017


Key facts

  • Leprosy is a chronic disease caused by a bacillus, Mycobacterium leprae.
  • M. leprae multiplies slowly and the incubation period of the disease, on average, is 5 years. In some cases, symptoms may occur within 1 year but can also take as long as 20 years to occur.
  • 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.

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 in the early stages can prevent disability.

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

Elimination of leprosy as public health problem (defined as a registered prevalence of 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 leprosy case detection and awareness campaigns in several endemic countries. Integration of basic leprosy services into general health services has made diagnosis and treatment of the disease more accessible.

In 2016 WHO has launched 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.

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, enhanced coordination between partners, inclusion of persons affected by leprosy in programme management, 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 (0.18 cases per 10 000 people). The number of new cases reported globally in 2015 was 211 973 (0.21 new cases per 10 000 people). In 2014 the number of new cases reported was 213 899, and in 2013 the number of new cases reported was 215 656.

The number of new cases indicates the degree of continued transmission of infection. Global statistics show that 203 600 (96%) of new leprosy cases were reported from 22 priority countries.

Pockets of high endemicity still remain in some areas of many countries, including countries which report relatively few 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 is an age-old disease, described in the literature of ancient civilizations. 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 clofazimin added for multibacillary disease. This drug combination kills the pathogen and cures the patient.

Since 1995 WHO has provided MDT free of cost to all leprosy patients in the world. Free MTD was initially funded by The Nippon Foundation, and since 2000 it is donated through an agreement with Novartis who recently committed to extend the donation to at least 2020.

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 at global level.

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 cases per 10 000 people in 1983 to 0.2 cases per 10 000 people in 2015.
  • A dramatic decrease has been achieved in the global disease burden: from 5.2 million people with leprosy in 1985, to 805 000 people in 1995, 753 000 in 1999, and 176 176 people with leprosy at the end of 2015.
  • With the exception of few 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 though sporadic cases of resistance to a single drug are observed. Vigilance is enhanced through 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, which will ultimately contribute to eliminating leprosy.

Actions and resources required

In order to reach all patients, leprosy treatment needs to be optimally integrated into general health services. Specialist services are to be retained at referral level. Moreover, political commitment needs to be sustained in all countries even after reaching elimination. Monitoring of programme implementation needs to be strengthened. 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 promoting intersectoral collaboration and partnerships at the international and national levels.
  • Facilitating and conducting basic and operational research in all aspects of leprosy and maximizing 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.

In August 2016, WHO published an Operational Manual to facilitate adaptation and implementation of the Global Leprosy Strategy 2016‒2020. The purpose of this manual is to provide guidance for managers of national leprosy programmes (or equivalent entities) to adapt and implement the Global Leprosy Strategy according to the epidemiological burden of their own country.

WHO will soon publish a Monitoring and Evaluation Guide to facilitate the monitoring of the implementation of the strategy.

The Global Leprosy Programme is taking the lead in expanding the network for surveillance of drug resistance in leprosy, defined as a key intervention under the Global Leprosy Strategy. Improved surveillance guidelines are under preparation and integration of surveillance within WHO’s global antimicrobial resistance programme is being promoted.