leprosy

Introduction
Mysteries of the disease
Transmission
Course of the disease
Therapy
History

References & Edit History Quick Facts & Related Topics

Images & Videos

Sign reading Gandhiji Prem Nivas Leprosy Centre Titagarh conducted by Missionaries of Charity, with a crucifix above the sign on a decorated building facade.

Kalaupapa was the site of a leprosy treatment center

The surprising history of Christmas tinsel

At a Glance

leprosy summary

Quizzes

A Yorkshire terrier dressed up as a veterinarian or doctor on a white background. (dogs)

A Visit with the Word Doctor: Medical Vocabulary Quiz

44 Questions from Britannica’s Most Popular Health and Medicine Quizzes

Related Questions

Can leprosy be transmitted through unbroken skin?
Can leprosy enter the body through the nose?
Can leprosy treatment reverse nerve damage that has already become permanent?
Does leprosy usually shorten a person's life?
How can unnoticed injuries lead to deformities in people with leprosy?
How did European colonists and western African slaves bring leprosy to the Americas?
How did sulfone drugs change leprosy treatment in the 1940s?
How do tuberculoid leprosy and lepromatous leprosy differ?
How does dapsone interfere with the growth of Mycobacterium leprae?
How long does treatment for localized leprosy usually last?
How long is the usual incubation period before leprosy symptoms appear?
How was chaulmoogra oil used to treat leprosy before the 1940s?
What bacterium causes leprosy?
What does genetic evidence suggest about the ancient origins of Mycobacterium leprae?
What evidence links nine-banded armadillos to some leprosy cases in the southern United States?
What percentage of people are not susceptible to the leprosy bacillus?
What physical changes can lepromatous leprosy cause in the face?
What role did the Carville, Louisiana, facility play in the history of leprosy treatment?
What skin changes occur in tuberculoid leprosy?
When did leprosy begin to decline in much of Europe?
Where did G.H. Armauer Hansen make his discovery in 1873?
Where was the oldest archaeological evidence of leprosy found?
Who discovered the bacterium that causes leprosy?
Who was Baldwin IV of Jerusalem and why was he called the leper king?
Why can lepromatous leprosy damage the nose and palate?
Why can leprosy cause a loss of sensation?
Why can tuberculoid leprosy cause claw hand and foot deformities?
Why did effective drug treatment make leper colonies unnecessary?
Why did health authorities adopt the name Hansen’s disease?
Why did the World Health Organization recommend combination drug treatment for leprosy in the 1980s?
Why do the skin diseases called leprosy in the Bible not necessarily mean Hansen’s disease?
Why does multidrug therapy help prevent drug-resistant leprosy?
Why is leprosy difficult for most people to contract?
Why is prolonged close contact important in the transmission of leprosy?
Why was chaulmoogra oil eventually replaced as a leprosy treatment?
What are the different forms of anthrax in humans?
What causes plague and how is it transmitted?
What are the three clinical forms of plague in humans?
What causes tuberculosis?
How does tuberculosis spread?
What are the symptoms of pulmonary tuberculosis?
How is tuberculosis diagnosed?
What are the challenges in treating drug-resistant tuberculosis?
What is cholera?
How does cholera spread?

Health & Medicine Conditions & Diseases Infectious Diseases

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External Websites

Cleveland Clinic - Leprosy
WebMd - Leprosy: Causes, Symptoms, and Treatment
Healthdirect - Leprosy
MSD Manual - Professional Version - Leprosy
World Health Organization - Leprosy
BBC - Leprosy: the ancient disease scientists can't solve
Centers for Disease Control and Prevention - Hansen's Disease (Leprosy)
Dermnet - Leprosy

Britannica Websites

Articles from Britannica Encyclopedias for elementary and high school students.

leprosy - Children's Encyclopedia (Ages 8-11)
leprosy - Student Encyclopedia (Ages 11 and up)

leprosy

infectious disease

Also known as: Hansen disease, Hansen’s disease

Written by

Susannah C.J. Kearns

Communications officer, The Leprosy Mission International, Brentford, England.

Susannah C.J. KearnsAll

Fact-checked by

Britannica Editors

Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....

Britannica Editors

Last updated

Oct. 1, 2026 •History

leprosy, chronic infectious disease that affects the skin, the peripheral nerves (nerves outside the brain and spinal cord), and the mucous membranes of the nose, throat, and eyes. It is caused by the leprosy bacillus, Mycobacterium leprae. Destruction of the peripheral nerves by the bacillus leads to a loss of sensation, which, together with progressive tissue degeneration, may result in the extremities’ becoming deformed and eroded. In almost all cultures throughout history, leprosy has aroused...

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