Leprosy (Hansen's disease)

March 2012

Key facts

  • Leprosy is a chronic infectious disease caused by a slow-growing bacteria, Mycobacterium leprae (M. leprae).
  • The incubation period can range from 3 to 20 years.
  • Leprosy is not highly infectious. It is transmitted via droplets, from the nose and mouth, during close and frequent contacts with untreated cases.
  • An infectious case is rendered non-infectious after the very first dose of treatment.


  • Leprosy mainly affects the skin and peripheral nerves.
  • If left untreated, it can damage the nerves, leading to loss of sensation and the ability to sweat in the extremities and paralysis of muscles in the hands, feet and face.

Multidrug therapy

  • In 1981, a WHO study group recommended multidrug therapy
  • Since 1995, WHO has been providing free multidrug therapy for all patients in the world, initially through a fund provided by the Nippon Foundation and currently through donations provided by Novartis Foundation for Sustainable Development.
  • Multidrug therapy comprises three drugs: dapsone, rifampicin and clofazimine. Rifampicin and clofazimine were discovered in the early 1960s.
  • Multidrug therapy effectively kills M. leprae and cures the patient.
  • Multidrug therapy is safe, effective and easily administered under field conditions.
  • Treatment provided in the early stages averts disability.
  • Multidrug therapy is available in convenient monthly calendar blister packs.
  • WHO estimates that early detection and treatment with multidrug therapy has prevented about four million people from becoming disabled.
  • Multidrug therapy is very cost-effective as a health intervention, considering the economic and social losses averted.

Elimination of leprosy as a public health problem

  • Elimination does not mean there are no cases of leprosy in a country.
  • The technical definition of leprosy elimination (less than one case per 10 000 of population) was endorsed by WHO's Member States during the World Health Assembly in 1991.
  • The target was achieved globally in 2000. WHO's Western Pacific Region met the target in 1991, the very year the target was set.
  • 34 of the 37 countries and areas in the Western Pacific Region have eliminated leprosy, but many people are still affected (2873 cases reported in the Philippines in 2010).
  • The Federated States of Micronesia, Kiribati and the Marshall Islands have not achieved leprosy elimination.
  • Leprosy is considered one of the neglected tropical diseases.

Social aspects

  • Treatment with multidrug therapy is not the end of care for a person affected with leprosy.
  • A person affected with leprosy who does not receive treatment, or whose diagnosis and treatment are late, may suffer from disabilities in the eyes, hands and feet.
  • These physical disabilities are often accompanied by the social rejection and mental suffering caused by stigma and discrimination.
  • People affected by leprosy need counselling and rehabilitation
  • Efforts to fight stigma and discrimination must also be increased.

Integrated approach to leprosy services

  • Leprosy control activities should be implemented by the general health services and specialty/referral facilities.
  • There should be a smooth referral system. This is an integrated approach that improves access to treatment and reduces stigma and discrimination.

Burden of leprosy in the Western Pacific Region

  • The prevalence of leprosy in the Western Pacific Region has declined by nearly 90% over the past 10 years.
  • In 2010 there were 5,055 new cases reported and 8,386 cases were on treatment.
  • Among the countries in the Western Pacific Region, in 2010, the Philippines reported the highest number of new cases (2,041).