Leprosy (Hansen's Disease)

Reviewed on 8/8/2022

What is Leprosy?

Leprosy (Hansen's disease)
The progression of leprosy includes skin ulcers and lesions accompanied by loss of sensation and eventual loss of digits and other extremities.
  • Leprosy, also called Hansen's disease, is a chronic infectious disease that primarily affects the skin, the peripheral nerves, the mucosa of the upper respiratory tract, and the eyes. Leprosy can lead to progressive permanent damage to these structures, and the resulting devastating disfigurement and disability have led to the historical social stigma and isolation (leper colonies) of those affected by the disease.
  • Historically speaking, leprosy has existed since at least 4000 BC, and the disease was present and described in the ancient civilizations of China, India, and Egypt. The first known written reference to the disease on Egyptian papyrus dates from about 1550 BC. It is believed that leprosy was brought to Europe by the Romans and the Crusaders and that later the Europeans brought it to the Americas. For centuries, leprosy remained a poorly understood disease characterized by human suffering and social isolation.
  • In 1873, G.A. Hansen discovered the bacterial cause of this infectious disease. The first medication breakthrough occurred in the 1940s with the development of the drug dapsone, and later it was discovered that the bacteria which caused leprosy was more effectively killed by using multiple medications.
  • Leprosy is a curable disease with the use of multidrug therapy (MDT). In 1991, the World Health Assembly passed a resolution to eliminate leprosy as a public-health problem by the year 2000. The elimination of leprosy was defined as a prevalence rate of less than one case per 10,000 people in all countries, focused primarily on those where leprosy was commonly found.
  • In the year 2000, the global elimination of leprosy, according to the prevalence rate, was achieved. With assistance from the World Health Organization (WHO), MDT has been distributed free to all patients with leprosy since 1995. Though leprosy is still endemic in a few developing countries (primarily in the tropics), there has been a dramatic worldwide decrease in the prevalence of the disease due to this successful public-health initiative. Over the past 20 years, close to 16 million leprosy patients have been cured, and the prevalence rate of the disease has decreased by 90%.
  • Leprosy has been eliminated from 119 countries out of the 122 countries where previously leprosy had previously been deemed a public-health concern in 1985. Official reports from 115 countries around the world reported 232,857 new cases of leprosy in 2012, with about 95% of these cases occurring in only 16 different countries.
  • Countries in which leprosy is more commonly found include Angola, Bangladesh, Brazil, China, Central African Republic, Ethiopia, India, Indonesia, Madagascar, Myanmar, Nepal, Nigeria, Philippines, Sudan, South Sudan, Sri Lanka, United Republic of Tanzania, the Democratic Republic of the Congo, and Mozambique.
  • In the United States, according to the National Hansen's Disease Registry, 294 new cases were reported in 2010, with 65% of these cases occurring in California, Florida, Hawaii, Louisiana, New York, Texas, and Massachusetts. On average, 150-250 new cases of leprosy are diagnosed each year in the United States, with most cases occurring in immigrants.
  • However, because the bacteria can be found in wild animals (for example, armadillos and chimpanzees), it is unlikely that leprosy will be totally eliminated like smallpox.

Leprosy Causes

Leprosy is an acquired infectious disease that can affect individuals of all ages. It is caused by the acid-fast, rod-shaped bacteria Mycobacterium leprae, which was discovered in 1873 by G.A. Hansen.

  • Because the bacterium multiplies very slowly, the signs and symptoms of leprosy may not develop until much later after exposure to M. leprae (ranging from several weeks to 20 years or more).
  • Though humans are the major reservoir and host for infection with M. leprae, other animals such as armadillos, chimpanzees, mangabey monkeys, and macaques also serve as reservoirs of infection.
  • Leprosy is thought to be transmitted via droplets from the nose and mouth during close prolonged contact with affected individuals, though the exact route of transmission has yet to be proven definitively.
  • Not all individuals infected with M. leprae will go on to develop leprosy because only 5%-10% of the population is thought to be susceptible to the infection for immunological reasons.

Leprosy Symptoms and Signs

The signs and symptoms of leprosy can vary depending on the individual's immune response to M. leprae. The WHO classification system uses clinical manifestations (the number of skin lesions and nerve involvement) as well as skin smear results to distinguish between forms of the disease. The two major WHO classifications are paucibacillary (PB) leprosy and multibacillary (MB) leprosy. However, within the WHO's simplified classification there can be a fairly wide range of patient presentations.

  • Paucibacillary leprosy
    • Two to five skin lesions with negative skin smear results at all sites
  • Paucibacillary single lesion leprosy
    • One skin lesion with negative skin smear results
  • Multibacillary leprosy
    • More than five skin lesions with or without positive skin smear result at any site

The Ridley-Jopling classification is another classification system that is used globally in evaluating patients in clinical studies and contains five different classifications of leprosy that further define the patient's severity of symptoms and disease progression. The six different categories, in order of increasing severity of disease, include indeterminate leprosy, tuberculoid leprosy, borderline tuberculoid leprosy, mid-borderline leprosy, borderline lepromatous leprosy, and lepromatous leprosy.

In general, the signs and symptoms of leprosy may vary with the form of the disease and include the following:

  • Flat or raised skin lesions or nodules, often less pigmented than the surrounding skin, though they may appear reddish or copper colored
  • Single or multiple skin lesions are often found on cooler parts of the body such as the face, buttocks, and extremities
  • Thickening of the skin and peripheral nerves
  • Ulcerations of the skin
  • Peripheral nerve involvement leading to loss of sensation
  • Peripheral nerve involvement leads to muscle weakness (for example, clawed hand deformities, contractures, and foot drop)
  • Hoarseness
  • Testicular involvement leads to sexual dysfunction or sterility
  • Eye involvement includes eye pain, eye redness, inability to close the eyelids, corneal ulcers, and blindness
  • Loss of eyebrows and eyelashes
  • Destruction of the nasal cartilage

When to Seek Medical Care for Leprosy

Individuals should seek medical care for any of the following signs and symptoms, especially if they have traveled or lived in the tropics or an area where leprosy is endemic. 

  • Unexplained skin lesions or rash
  • Loss of sensation or tingling of the skin
  • Thickening of the skin
  • Muscle weakness and/or numbness in the extremities
  • Eye pain or vision changes

It is important to note that the following findings may not be apparent for months to years after exposure to M. leprae.

Occasionally during or after the treatment of leprosy with MDT, an acute inflammatory state may be induced which requires the immediate attention of a healthcare professional. Prompt management is necessary to avoid potential permanent neurologic damage from the following conditions:

  • Type 1 reaction (also known as reversal reaction)
    • This reaction may lead to new skin lesions, skin redness, swelling of existing lesions, and nerve inflammation and tenderness.
  • Type 2 reaction (also known as erythema nodosum leprosum [ENL])
    • This reaction is characterized by the appearance of inflamed painful nodules under the skin. It may be associated with fever and joint pain.

Leprosy Diagnosis

The diagnosis of leprosy is often established from the patient's clinical signs and symptoms. A careful skin exam and neurologic exam will be undertaken by a healthcare professional. If a laboratory is available, skin smears or skin biopsies may be obtained for a more definitive diagnosis.

Skin smears or biopsy material that show acid-fast bacilli with the Ziel-Neelsen stain or the Fite stain can diagnose multibacillary leprosy. If bacteria are absent, paucibacillary leprosy can be diagnosed. Other less commonly used tests include blood exams, nasal smears, and nerve biopsies.

Specialized tests can be done to place the patient in the more detailed Ridley-Jopling classification.

Self-Care at Home for Leprosy

Prescribed antibiotics medications are the primary treatment for leprosy. Compliance with the full course of antibiotics is crucial to successful treatment.

Patients should also be educated to closely inspect their hands and feet for possible injuries sustained which may go unnoticed because of the loss of sensation.

  • Ulcers or tissue damage can result, leading to skin infections and disability.
  • Proper footwear and injury prevention should be encouraged.

Leprosy Treatment

Leprosy is a curable disease using highly effective MDT (multidrug therapy).

  • In 1981, a World Health Organization Study Group recommended multidrug treatment with three medications: dapsone, rifampicin (Rifadin), and clofazimine (Lamprene).
  • This long-term treatment regimen cures the disease and prevents the complications associated with leprosy if started in its early stages.
  • These medications have been distributed free to all patients with leprosy since 1995, and the WHO distributes the medications in convenient monthly calendar blister packs.
  • After the first doses of these medications, patients are no longer infectious and they do not transmit the disease to others.
  • Widespread resistance of M. leprae to a full course of MDT has not developed.

The National Hansen's Disease Program (NHDP) currently recommends different treatment regimens for patients with tuberculoid and lepromatous leprosy.

  • NHDP recommendations
    • Tuberculoid leprosy
      • Twelve months of treatment using rifampin and Dapsone daily
    • Lepromatous leprosy
      • Twenty-four months of treatment using rifampin, dapsone, and clofazimine daily

The WHO recommended therapy for leprosy is given significantly shorter and less often, as this treatment policy is based upon practical considerations in countries with fewer medical resources. However, the relapses with treatment according to the WHO recommendations are significantly greater than those with the NHDP recommended therapy.

Individuals who develop type 1 or type 2 reactions may require other medications.

  • Type 1 reaction (reversal reaction)
    • Treatment may include the use of corticosteroids, salicylates, and nonsteroidal anti-inflammatory drugs (NSAIDs).
  • Type 2 reaction (ENL)
    • Treatment may include the use of corticosteroids, salicylates, NSAIDs, clofazimine, and thalidomide (Thalomid).

Surgical Therapy for Leprosy

There are various surgical procedures available for certain patients with leprosy. These surgical procedures are aimed at restoring the function of affected body parts (for example, correcting clawed hand deformities) and cosmetically improving areas damaged by the disease.

Amputation of affected body parts is sometimes necessary. Surgery may also be necessary to drain a nerve abscess (pus collection) or to relieve the compression of nerves.

Leprosy Follow-up

Patients should maintain close contact with their healthcare professional during treatment with MDT, and periodic follow-up visits are recommended.

  • The WHO recommends monthly direct supervision by a healthcare professional during the administration of rifampicin.
  • Periodic blood testing during treatment is recommended, as well as yearly skin scrapings when possible.
  • The relapse rate after the administration of MDT is 1% for both types of leprosy. Therefore, patients should still be followed by a healthcare professional for five to 10 years after completion of MDT.
  • Some patients with leprosy may require psychological counseling, physical therapy, and occupational therapy.

Leprosy Prevention

The prevention of leprosy ultimately lies in the early diagnosis and treatment of those individuals suspected or diagnosed as having leprosy, thereby preventing further transmission of the disease to others.

  • Public education and community awareness are crucial to encourage individuals with leprosy and their families to undergo evaluation and treatment with MDT.
  • Household contacts of patients with leprosy should be monitored closely for the development of leprosy signs and symptoms.
  • A study demonstrated that prophylaxis with a single dose of rifampicin was 57% effective in preventing leprosy for the first two years in individuals who have close contact with newly diagnosed patients with leprosy.
  • There is currently no widely used standard for using medications for the prevention of leprosy.
  • Currently, there is no single commercial vaccine that confers complete immunity against leprosy in all individuals.
  • Several vaccines, including the BCG vaccine, provide variable levels of protection against leprosy in certain populations.

Leprosy Prognosis

  • Leprosy is a curable disease with the initiation and completion of MDT.
  • Treatment with MDT can prevent the disfigurement and neurologic disability associated with leprosy.
  • Prognosis depends on the stage of the disease at the time of diagnosis, as well as on the initiation and compliance with MDT.
  • Skin discoloration and skin damage generally persist even after treatment with MDT.
  • Progression of neurologic impairment can be limited with MDT. In general, however, there is partial or no recovery from neurologic damage already suffered (muscle weakness and loss of sensation).
  • Relapse of leprosy after treatment with MDT is rare.
  • Leprosy is only rarely fatal.
  • Patients must be educated to be aware of the signs and symptoms of relapse and disease exacerbations (type 1 and type 2 reactions).
  • Injury prevention is important to avoid chronic disability.
  • Public awareness and education campaigns are necessary for the early identification and treatment of leprosy, in addition to eliminating the social stigma and isolation associated with the disease.
  • The WHO public health initiative has been extremely successful in working toward the elimination of leprosy worldwide. Political and economic support needs to continue in order to sustain elimination and progress toward further reducing the prevalence of leprosy globally.

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Reviewed on 8/8/2022
Medically reviewed by Robert Cox, MD; American Board of Internal Medicine with subspecialty in Infectious Disease


Davis, Charles P. "Leprosy (Hansen's Disease)." MedicineNet.com. Dec. 10, 2010. <https://www.medicinenet.com/leprosy/article.htm>.

Smith, Darvin Scott. "Leprosy." Medscape.com. July 6, 2011. <http://emedicine.medscape.com/article/220455-overview>.

Switzerland. World Health Organization. "Leprosy Elimination." <http://www.who.int/lep/en/>.