Key facts

• Leprosy is a chronic infectious disease caused by Mycobacterium leprae that mainly affects the skin and nerves.
• The disease progresses slowly, and symptoms may take years to appear.
• Leprosy is curable and early diagnosis and treatment prevent disability and stop the disease’s spread.
• While the disease is nowhere near as widespread as it once there are still around 200,000 cases a year

Overview

The disease is caused by the bacterium Mycobacterium leprae, which primarily damages the skin and peripheral nerves. Leprosy develops slowly, and its incubation period is unusually long, ranging from several years to over a decade.

Leprosy is not highly contagious, and most people exposed to the bacterium never develop the disease. However, if left untreated, it can cause irreversible damage to nerves, skin, and other tissues. Stigma remains one of the greatest challenges, often leading to discrimination and social isolation for those affected.

Signs and symptoms

The first signs of leprosy are usually changes to the skin and nerves. Symptoms may be mild at the onset and progress slowly over years, making diagnosis difficult in the early stages.

Common symptoms include:

• Discoloured or light patches of skin
• Numbness or tingling in hands, feet, arms, or legs.
• Muscle weakness or paralysis, particularly in hands and feet.
• Thickened skin or nodules.
• Ulcers on the soles of the feet.

Dangers and complications

If untreated, advanced leprosy can cause severe and permanent nerve damage. Hands and feet can become crippled and paralysed.

Complications also include blindness due to damage to the eyes, kidney failure, and disfigurement caused by skin nodules. Stigma and discrimination can have profound psychological and social consequences, often isolating individuals from their communities.

Transmission

Leprosy is spread through droplets from the nose and mouth of untreated individuals, usually during prolonged close contact. It is not spread by casual contact such as shaking hands, sharing meals, or touching.

Treatment

Leprosy is curable with a combination of three antibiotics for six months or 12 months, depending which type of leprosy the patient has. Since 2000 the treatment has been provided free of charge by drug company Novartis.

Prevention

Prevention relies on early detection, timely treatment of patients, and monitoring of close contacts. Prompt treatment stops its spread. A single dose of the antibiotic rifampicin is given as a prophylaxis to close contacts of affected individuals.

History

Leprosy is one of the most ancient and feared diseases, with references to it in the Bible. It is thought to have originated in India before spreading to Europe, where it died out by the 1600s – the reasons for this are unclear although some believe that improved immune systems and living conditions may have played a part.

Because of the severe disfigurement suffered by people with leprosy, huge stigma and fear grew up around the disease. Transmission was poorly understood and patients were exiled to leper colonies and sanatoria, removed from society. In 1873 a Norwegian physician, Gerhard Armauer Hansen, discovered the bacterium that causes leprosy – the condition is sometimes known as Hansen’s disease. The advent of antibiotics and advances in science has led to the disease’s decline.

Useful links

who.int/fact-sheets/leprosy

cdc.gov/leprosy/about

leprosymission.org/the-history-of-leprosy

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