What Is Leprosy?

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Leprosy, known as Hansen’s Disease, is a disease from ancient times that still exists today. It affects the skin, peripheral nerves, and mucosal membranes. Across the world, there were more than 127,000 new cases in 2020, according to the World Health Organization (WHO). More than 16 million people have been cured of this disabling, disfiguring disease since treatments became available in the 1980s.

The first breakthrough came in 1873, when Dr. Armauer Hansen of Norway found it was caused by the Mycobacterium leprae bacteria. In the 1940s, there was a drug to treat leprosy, and in the early 1960s, there were two more. Today, all three are used together to treat leprosy in people.

An illustration with symptoms of leprosy

Illustration by Julie Bang for Verywell Health

Leprosy also occurs in animals, like armadillo, and is considered a zoonotic disease in the United States. That means it can be transmitted from animals to people.

This article explains the causes and symptoms of leprosy. More important is that it will help you to understand that leprosy can be cured, and why it is so critical to seek and complete treatment.

Symptoms of Leprosy

The earliest sign of leprosy is commonly a spot on the skin that may be slightly redder, darker, or lighter than the person’s normal skin. Symptoms vary based on what body part is affected.

The Leprosy Mission
Stephen J. Boitano / Getty Images

Symptoms related to the skin include:

  • Small growths on the skin
  • Thick or stiff skin
  • Painless sores on the soles of feet
  • Swelling or lumps on the face and ears
  • Loss of eyebrow or eyelash hair

If left untreated, leprosy can cause nerve damage. This usually begins as a sense of numbness in spots where nerves are involved. Leprosy may then progress to cause the following symptoms:

  • Paralysis in the hands or feet
  • Potential amputation of the hands or feet
  • Permanent curling or total loss of toes or fingers
  • Loss of vision if nerves around the eyes are infected
  • Nosebleeds


Experts say about 95% of people have a natural immunity to the disease. Leprosy also is not very contagious.

But when it is, leprosy is spread through the air through droplets when someone with an untreated case coughs or sneezes. This close contact is important, and it’s one reason why the WHO recommends anyone who has been in contact with an infected person also get treated.

The National Hansen’s Disease Program makes the first connection between leprosy and animals in 2011. Specifically, researchers discovered that about a third of the leprosy cases that arise yearly in the United States almost certainly result from contact with infected armadillos.

Another study in 2015 confirmed leprosy in both the armadillo and humans in the southeastern U.S.

Additional studies since then have found zoonotic leprosy in other countries and other animals, including monkeys. This supports concern over animal-human transmission.


Leprosy cases continue around the world, as the bacterial infection is spread from human to human or through contact with infected animals. It has been curable since 1981, and the damage can be limited if people seek treatment fast enough. Because leprosy is so rare in the United States, it’s important to tell your healthcare provider if you think you may have symptoms.


Leprosy is diagnosed by taking a skin sample (biopsy) and examining it under a microscope to look for leprosy bacteria.

Another test used for diagnosis is a skin smear. A small cut is made in the skin, and a small amount of tissue fluid is taken. This also is put under a microscope to confirm the presence of leprosy bacteria.


The good news is that leprosy is curable. In 1981, WHO recommended using multidrug therapy (MDT), a combination of three antibiotics—usually dapsone, rifampicin, and clofazimine—for treatment. This treatment may take six months to a year.

In 2018, WHO continued the multidrug approach but also added a single-dose approach using rifampicin for leprosy prevention in family, friends, and other social contacts of a confirmed case. WHO has made these antibiotics free since 1995.

During the course of treatment, the body may react to the dead bacteria with pain and swelling in the skin and nerves. This is treated with medication. In 2020, WHO also issued guidelines for treating the recurring inflammation that happens in about 50% of cases.


Before treatment was available, a diagnosis of leprosy meant suffering and pain and being shunned by society. Today, antibiotics and good skin care prevent the disease from destroying the body. Perhaps in the future, a vaccine will eliminate it altogether.


Leprosy is an ancient disease with a historical stigma attached. Yet it’s also a modern disease, with thousands of cases yearly—including some in the developed world. What may seem like a rash can grow into a serious bacterial infection that affects vision and may cause paralysis or the loss of feet and hands should it progress.

Fortunately, people respond well to treatment where it is available. The risk may be low in the U.S., but knowing the symptoms of leprosy and how it is treated may be the best way to protect yourself and those around you.

A Word From Verywell

Many people in the United States have heard of leprosy but think it’s a condition seen only in the developing world. But that’s not true. The Centers for Disease Control and Prevention says that 150 to 250 cases are reported yearly in the U.S. There’s no reason to be overly vigilant because it’s still quite rare. What it does mean is that leprosy may seem obvious in another country but get missed in the U.S. If you have reason to think it’s leprosy, insist that a healthcare provider checks for that.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Mary Kugler, RN
Mary Kugler, RN, is a pediatric nurse whose specialty is caring for children with long-term or severe medical problems.