Hansen’s disease, once known as leprosy, is a bacterial infection that affects the nervous system, skin, nose, and eyes. It is curable. But without early treatment, it can cause irreversible damage.

In the past, people believed that Hansen’s disease could spread easily. Now, experts know that this is not true, and treatment can cure the infection. However, the treatment cannot reverse any existing damage.

The bacteria responsible, called Mycobacterium leprae,grow very slowly and do not spread easily. People with Hansen’s disease can continue to work and have active lives during their treatment.

In the United States, around 150 people receive a diagnosis of Hansen’s disease each year, according to the Centers for Disease Control and Prevention (CDC). In 2018, there were about 208,600 registered cases throughout the world.

This article looks at the symptoms of Hansen’s disease, how doctors diagnose it, and the treatment options.

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The bacteria that cause Hansen’s disease grow slowly, and symptoms can take up to 20 years to appear. Often, a person does not notice the changes or otherwise realize that the disease is progressing.

In time, a person may notice a decreased ability to feel touch and pain, as well as skin changes.

In 90% of people with Hansen’s disease, the first noticeable symptom is numbness. This loss of sensation may begin several years before skin changes occur, and it usually concerns:

  1. temperature
  2. light touch and pain
  3. deep pressure

The numbness can increase the risk of injuries and infections.

The first skin changes usually involve one or a few patches of skin losing their color. Other skin changes include:

  • lightening or darkening
  • dryness or flakiness
  • signs of inflammation, such as redness
  • a burning sensation
  • the growth of nodules
  • the formation of painless ulcers on the feet
  • thickened skin surrounding lesions
  • lumps or swellings of the face or earlobes

The symptoms can vary from person to person. As well as skin changes and a loss of sensation, Hansen’s disease can cause:

  • nasal congestion and nosebleeds
  • muscle weakness
  • weakness and numbness in the hands and feet
  • swollen nerves, especially around the knees, elbows, and neck
  • enlarged nerves, especially in the elbows and knees
  • problems with the eyes

As the condition progresses, a person may develop:

  • a loss of eyebrows
  • ulcers on the soles of the feet that do not heal
  • paralysis and distortion of the hands and feet
  • a “disappearance” of the fingers and toes, as their cartilage shortens and the body reabsorbs them
  • vision loss

Also, damage to the mucous membrane inside the nose can sometimes lead to internal damage and scarring. As this affects the septum, which is the cartilage between the nostrils, the nose might eventually collapse.

The disease can affect the nerves responsible for blinking, causing the eyes to become very dry and prone to infection. Ulceration and vision loss can result.

A physician usually diagnoses Hansen’s disease by considering the symptoms. Testing a skin or nerve sample in a laboratory can confirm the diagnosis.

To treat the disease, the doctor prescribes a combination of two or three antibiotics. A person needs this treatment for 1–2 years. Combining several antibiotics helps reduce the risk of developing antibiotic resistance, according to the CDC.

Once a person starts the treatment, the bacteria cannot pass to others. However, take care to:

  • avoid injuries that may lead to further damage
  • report any new symptoms to the doctor, especially if there are signs of inflammation, fever, or new areas of skin change or numbness
  • take the full course of antibiotics as the doctor prescribed it

Antibiotics can kill the bacteria causing the symptoms, stopping the disease. However, it cannot reverse existing damage. It is essential to contact a doctor as soon as possible if the symptoms start to appear.

In the U.S., there is a dedicated program, the National Hansen’s Disease (Leprosy) Program, that provides treatment throughout the country and Puerto Rico, and it also carries out research.

Hansen’s disease is a bacterial infection. The main bacterium responsible is M. leprae.

In 2008, however, scientists identified another type, Mycobacterium lepromatosis, in Mexico. These bacteria produce slightly different symptoms. So far, there has been very little research into this type.

The bacteria spread slowly through the body. As they do so, they attack macrophages, which are cells that represent a key part of the immune system and support the nervous system. This can lead to a thickening of the nerves under the skin.

The authors of a 2015 review reached no definite conclusion regarding how the bacteria transmit. The studies they analyzed suggested that the transmission might involve contact with animals, skin-to-skin contact, or droplets from a cough or sneeze.

The World Health Organization (WHO) report that the bacteria most likely transmit through droplets from the nose and mouth during close, frequent contact with a person who has untreated Hansen’s disease.

Hansen’s disease is not particularly contagious. Around 95% of people have a natural immunity to the bacteria and, even after prolonged exposure, do not develop symptoms.

Hansen’s disease develops slowly. A person would need to be in close contact with someone who has the disease, but is not receiving treatment, for several months in order to contract it.

According to the CDC, the bacteria that cause Hansen’s disease cannot pass on through:

  • casual contact
  • shaking hands or hugging
  • sitting nearby
  • eating together
  • sexual contact

The bacteria also do not pass to a fetus during pregnancy.

Some armadillos may carry the bacteria. Anyone who has regular contact with armadillos should speak with their doctor about appropriate precautions.

Hansen’s disease progresses slowly and is not highly contagious. Once a person starts treatment, the bacteria cannot pass on to others.

However, a stigma remains, and many people with the condition experience prejudice and discrimination. These can also lead to further complications.

Some problems facing people with noticeable signs of the disease include:

  • reduced job opportunities
  • lower pay for the same work as someone without the condition
  • difficulty finding a partner
  • rejection from the community
  • isolation and marginalization
  • feelings of worthlessness

These and other pressures can increase the risk of mental health problems, leading to further isolation, and possibly an inability to continue with treatment.

The stigma can affect others, too. For example, a person with Hansen’s disease may stop breastfeeding their baby due to a mistaken belief that the bacteria can pass on in this way.

Also, a fear of discrimination may cause a person to hide their symptoms and avoid seeking support or treatment, according to older research published in 2010.

However, the longer treatment is delayed, the greater the chance of experiencing irreversible damage and severe complications. Delays also provide more opportunity for the bacteria to transmit to others.

Hansen’s disease, once called leprosy, is a curable bacterial infection. In the past, people believed that it was highly contagious, but this is not true. Symptoms develop slowly and often start with numbness.

Treatment with antibiotics can cure the infection, but it cannot reverse any damage.

If a person may have Hansen’s disease, they should receive medical attention as soon as possible to prevent lasting damage and complications.