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Leprosy is a slowly progressing bacterial infection that affects the skin, peripheral nerves in the hands and feet, and mucous membranes of the nose, throat, and eyes. Destruction of the nerve endings causes the the affected areas to lose sensation. Occasionally, because of the loss of feeling, the fingers and toes become mutilated and fall off, causing the deformities that are typically associated with the disease.


Leprosy is also known as Hansen's disease after G. A. Hansen, who in 1878 identified the bacillus Mycobacterium leprae that causes the disease.
The infection is characterized by abnormal changes of the skin. These changes, called lesions, are at first flat and red. Upon enlarging, they have irregular shapes and a characteristic appearance. The lesions are typically darker in color around the edges with discolored pale centers. Because the organism grows best at lower temperatures the leprosy bacillus has a preference for the skin, the mucous membranes and the nerves. Infection in and destruction of the nerves leads to sensory loss. The loss of sensation in the fingers and toes increases the risk of injury. Inadequate care causes infection of open wounds. Gangrene may also follow, causing body tissue to die and become deformed.
Because of the disabling deformities associated with it, leprosy has been considered one of the most dreaded diseases since biblical times, though much of what was called leprosy in the Old Testament most likely was not the same disease. Its victims were often shunned by the community, kept at arm's length, or sent to a leper colony. Many people still have misconceptions about the disease. Contrary to popular belief, it is not highly communicable and is extremely slow to develop. Household contacts of most cases and the medical personnel caring for Hansen's disease patients are not at particular risk. It is very curable, although the treatment is long-term, requiring multiple medications.
The World Health Organization (WHO) puts the number of identified leprosy cases in the world at about 600,000 as of the early 2000s. Seventy percent of all cases are found in just three countries: India, Indonesia, and Myanamar (Burma). The infection can be acquired, however, in the Western Hemisphere as well. There are about 5000 reported cases in the United States as of 2004, almost all of which involve immigrants from developing countries. Cases also occur in some areas of the Caribbean. Although it was thought for many years that only humans are affected by the disease, 15% of wild armadillos in southern Texas and Louisiana have been found to be infected with M. leprae.

Causes and symptoms

The organism that causes leprosy is a rod-shaped bacterium called Mycobacterium leprae. This bacterium is related to Mycobacterium tuberculosis, the causative agent of tuberculosis. Because special staining techniques involving acids are required to view these bacteria under the microscope, they are referred to as acid-fast bacilli (AFB).
When Mycobacterium leprae invades the body, one of two reactions can take place. In tuberculoid leprosy (TT), the milder form of the disease, the body's immune cells attempt to seal off the infection from the rest of the body by surrounding the offending pathogen. Because this response by the immune system occurs in the deeper layers of the skin, the hair follicles, sweat glands, and nerves can be destroyed. As a result, the skin becomes dry and discolored and loses its sensitivity. Involvement of nerves on the face, arms, or legs can cause them to enlarge and become easily felt by the doctor. This finding is highly suggestive of TT. The scarcity of bacteria in this type of leprosy leads to it being referred to as paucibacillary (PB) leprosy. Seventy to eighty percent of all leprosy cases are of the tuberculoid type.
In lepromatous (LL) leprosy, which is the second and more contagious form of the disease, the body's immune system is unable to mount a strong response to the invading organism. Hence, the organism multiplies freely in the skin. This type of leprosy is also called the multibacillary (MB) leprosy, because of the presence of large numbers of bacteria. The characteristic feature of this disease is the appearance of large nodules or lesions all over the body and face. Occasionally, the mucous membranes of the eyes, nose, and throat may be involved. Facial involvement can produce a lion-like appearance (leonine facies). This type of leprosy can lead to blindness, drastic change in voice, or mutilation of the nose. Leprosy can strike anyone; however, children seem to be more susceptible than adults.
Well-defined skin lesions that are numb are the first symptoms of tuberculoid leprosy. Lepromatous leprosy is characterized by a chronic stuffy nose due to invasion of the mucous membranes, and the presence of nodules and lesions all over the body and face.
Although patients with leprosy are commonly thought not to suffer pain, neuroapthic pain caused by inflammation of peripheral nerve endings is increasingly recognized as a major complication of the disease in many patients. Corticosteroids may be given to reduce the inflammation.
The incubation period of the leprosy bacillus varies anywhere from six months to ten years. On an average, it takes four years for the symptoms of tuberculoid leprosy to develop. Probably because of the slow growth of the bacillus, lepromatous leprosy develops even more slowly, taking an average of eight years for the initial lesions to appear.
It is still not very clear how the leprosy bacillus is transmitted from person to person; about 50% of patients diagnosed with the disease have a history of close contact with an infected family member. Since untreated patients have a large number of M. leprae bacilli in their nasal secretions, it is thought that transmission may take place via nasal droplets. The milder tubercular form of leprosy may be transmitted by insect carriers or by contact with infected soil.
The incidence of leprosy is highest in the poverty belt of the globe. Therefore, environmental factors such as unhygienic living conditions, overpopulation, and malnutrition may also be contributing factors favoring the infection.
It is also possible that genetic factors are involved in susceptibility to leprosy. In 2003, scientists conducting a genome scan of a large Vietnamese family with many cases of leprosy found that susceptibility to the disease was linked to region q25 on the long arm of chromosome 6. Further study indicated that the leprosy susceptibility gene lies within a region shared by two genes for Parkinson's disease. Further research may confirm that the emergence of leprosy in certain individuals is related to inheritance of genes for Parkinson's disease.


One of the hallmarks of leprosy is the presence of AFB in smears taken from the skin lesions, nasal scrapings, or tissue secretions. In patients with LL leprosy, the bacilli are easily detected; however, in TT leprosy the bacteria are very few and almost impossible to find. In such cases, a diagnosis is made based on the clinical signs and symptoms, the type and distribution of skin lesions, and history of having lived in an endemic area.
The signs and symptoms characteristic of leprosy can be easily identified by a health worker after a short training period. There is no need for a laboratory investigation to confirm a leprosy diagnosis, except in very rare circumstances.
In an endemic area, if smears from an individual show the presence of AFB, or if he has typical skin lesions, he should definitely be regarded as having leprosy. Usually, there is slight discoloration of the skin and loss of skin sensitivity. Thickened nerves accompanied by weakness of muscles supplied by the affected nerve are very typical of the disease. One characteristic occurrence is a foot drop where the foot cannot be flexed upwards, affecting the ability to walk.


The most widely used drug for leprosy is dapsone (DDS). However, the emergence of dapsone-resistant strains prompted the introduction of multidrug therapy, or MDT. MDT combines dapsone, rifampin (Rifadin; also known as rifampicin), and clofazimine (Lamprene), all of which are powerful antibacterial drugs. Patients with MB leprosy are usually treated with all three drugs, while patients with PB leprosy are only given rifampin and dapsone. Usually three months after starting treatment, a patient ceases being infectious, though not everyone with this disease is necessarily infectious before treatment. Depending on the type of leprosy, the time required for treatment may vary from six months to two years or more.
Each of the drugs has minor side effects. Dapsone can cause nausea, dizziness, palpitations, jaundice and rash. A doctor should be contacted immediately if a rash develops. Dapsone also interacts with the second drug, rifampin. Rifampin increases the metabolizing of dapsone in the body, requiring an adjustment of the dapsone dosage. rifampin may also cause muscle cramps, or nausea. If jaundice, flu-like symptoms or a rash appear, a doctor should be contacted immediately. The third drug, clofazimine may cause severe abdominal pain and diarrhea, as well as discoloration of the skin. Red to brownish black discoloration of the skin and bodily fluids, including sweat, may persist for months to years after use.
Thalidomide, the most famous agent of birth defects in the twentieth century, is now being used to treat complications of leprosy and similar diseases. Thalidomide regulates the immune response by suppressing a protein, tumor necrosis factor alpha.
Leprosy patients should be aware that treatment itself can cause a potentially serious immune system response called a lepra reaction. When antibiotics kill M. leprae, antigens (the proteins on the surface of the organism that initiate the body's immune system response) are released from the dying bacteria. In some people, when the antigens combine with the antibodies to M. Leprae in the bloodstream, a reaction called erythema nodosum leprosum may occur, resulting in new lesions and peripheral nerve damage. Cortisonetype medications and, increasingly, thalidomide are used to minimize the effects of lepra reactions.
In some cases, severe ulcers caused by leprosy may be treated surgically with small skin grafts.


Leprosy is curable; however, the deformities and nerve damage associated with leprosy are often irreversible. Preventions or rehabilition of these defects is an integral part of management of the disease. Reconstructive surgery, aimed at preventing and correcting deformities, offers the greatest hope for disabled patients. Sometimes, the deformities are such that the patients will not benefit from this type of surgery.
Comprehensive care involves teaching patients to care for themselves. If the patients have significant nerve damage or are at high risk of developing deformities, they must be taught to take care of their insensitive limbs, similar to diabetics with lower leg nerve damage. Lacking the sensation of pain in many cases, the patients should constantly check themselves to identify cuts and bruises. If adequate care is not taken, these wounds become festering sores and a source of dangerous infection. Physiotherapy exercises are taught to the patients to maintain a range of movement in finger joints and prevent the deformities from worsening. Prefabricated standardized splints are available and are extremely effective in correcting and preventing certain common deformities in leprosy. Special kinds of footwear have been designed for patients with insensitive feet in order to prevent or minimize the progression of foot ulcers.


By early diagnosis and appropriate treatment of infected individuals, even a disease as ancient as leprosy can be controlled. People who are in immediate contact with the leprosy patient should be tested for leprosy. Annual examinations should also be conducted on these people for a period of five years following their last contact with an infectious patient. Some physicians have advocated dapsone treatment for people in close household contact with leprosy patients.
The WHO Action Program for the Elimination of Leprosy adopted a resolution calling for the elimination of leprosy around the world by the year 2005. This goal is not likely to be reached, however; a computer simulation performed for WHO by a team of Dutch researchers in 2004 indicates that leprosy is likely to persist in some parts of the world until 2020, although its incidence will continue to decline.

Key terms

Endemic area — A geographical area where a particular disease is prevalent.
Gangrene — Death of tissue due to loss of blood supply followed by bacterial invasion and putrefaction.
Incubation period — The time it takes for symptoms to develop after initial exposure to a disease-causing organism.
Lesion — Any visible, local abnormality of the tissues of the skin, such as a wound, sore, rash, or boil.
Mucous membranes — The inner tissue that covers or lines body cavities or canals open to the outside, such as nose and mouth. These membranes secrete mucus and absorb water and salts.
Nasal scraping — Pathological material obtained for clinical study by scratching the inner surface of the nose with a clinical instrument.
Nodules — A small mass of tissue in the form of a protuberance or a knot that is solid and can be detected by touch.
Pathogen — Any disease-producing agent or microorganism.
Smear — A specimen prepared for microscopic study by spreading the material across a slide and treating it with a specific stain.



Beers, Mark H., MD, and Robert Berkow, MD., editors. "Infectious Diseases Caused by Mycobacteria." In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.


Buschman, E., and E. Skamene. "Linkage of Leprosy Susceptibility to Parkinson's Disease Genes." International Journal of Leprosy and Other Mycobacterial Diseases 72 (June 2004): 169-170.
Jayaseelan, A., and W. Aithal. "Pinch Skin Grafting in Non-Healing Leprous Ulcers." International Journal of Leprosy and Other Mycobacterial Diseases 72 (June 2004): 139-142.
Meima, A., W. C. Smith, G. J. van Oortmarssen, et al. "The Future Incidence of Leprosy: A Scenario Analysis." Bulletin of the World Health Organization 82 (May 2004): 373-380.
Stump, P. R., R. Baccarelli, L. H. Marciano, et al. "Neuropathic Pain in Leprosy Patients." International Journal of Leprosy and Other Mycobacterial Diseases 72 (June 2004): 134-148.


American Leprosy Missions. 1 ALM Way, Greenville, SC 29601. (1-800-LEPROSY).
British Leprosy Relief Association, LEPRA. Fairfax House, Causton Road, Colchester, Essex CO1 1PU, UK.
INFOLEP, Leprosy Information Services. Postbus 95005,1090 HA, Amsterdam, Netherlands. 〈Infolep@antenna.nl〉.
WHO/LEP, Action Programme for the Elimination of Leprosy. 20 Avenue Appia CH-1211, Geneva 27, Suisse. 〈http://www.who.ch/programmes/lep/lep_home.htm〉.


Cherath, Lata. "Leprosy." A Healthy Me Page. http://www.ahealthyme.com/topic/topic100587076.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


an inflammatory disease caused by Mycobacterium leprae, manifested in various ways, depending on the host's ability to develop cell-mediated immunity. It is a chronic communicable disease characterized by the production of granulomatous lesions of the skin, mucous membranes, and peripheral nervous system. Not readily contagious, it often results in severe disability but is rarely fatal. Called also Hansen's disease. adj., adj lep´rous.
Frequency and Transmission. Leprosy is essentially a tropical disease, although it has occurred in every country in the world. According to the World Health Organization, the number of leprosy patients in the world was less than 600,000 at the beginning of 2001. Its control remains a problem in six countries: Brazil, India, Madagascar, Mozambique, Myanmar, and Nepal.

Leprosy is not inherited, but the actual means of transmission have not yet been established. It is known that the source of infection is the discharge from lesions of persons with active cases. It is believed that the bacillus enters the body through the skin or through the mucous membranes of the nose and throat. Leprosy is considered one of the least contagious of infectious diseases; only 3 to 5 per cent of those exposed to it ever contract it.
Symptoms. The average incubation period of leprosy is 3 years. Initially, the infection is confined to the sheaths of nerves in the dermis. The disease progresses by spreading up the nerve sheath, resulting in loss of sensation, or by forming subcutaneous nodules and skin lesions.

In the lepromatous type, open sores later appear on the face, earlobes, and forehead, with tests showing large numbers of bacilli in the discharge from these lesions. If progress of the disease is not checked by treatment, the fingers and toes disintegrate and there may be other disfiguring due to trauma to the insensitive extremities. Death may occur in extreme cases of this type, but more often it is due to a secondary infection, such as tuberculosis or pneumonia.

In the tuberculoid type, there is loss of sensation on sections of the skin and atrophy of muscles. This often results in contraction of the hand into a claw.

Leprosy is further classified as either paucibacillary or multibacillary according to whether there are fewer or more than five lesions or patches present.
Treatment. Leprosy is most effectively and inexpensively treated with sulfone medications, such as dapsone, developed around 1950. In cases of sulfone resistance, the drug clofazimine (Lamprone) may be prescribed. A semisynthetic antibacterial, rifampin, is very effective in killing leprosy bacilli rapidly, so that patients receiving it may be considered minimal public health risks within a few days after treatment is begun. However, these drugs are expensive, have serious side effects, and are not readily available in many countries.

Treatment continues for several years at least, and sometimes indefinitely. In addition to specific medical therapy, adequate rest, diet, and exercise are provided. Physical therapy is employed to retrain affected muscles. Psychiatric help, not only for leprosy patients but for their close contacts and those who only imagine they have been exposed, is invaluable in relieving the anxieties arising from the age-old misconceptions about the disease.
Prevention. Preventive measures include establishment of clinics and hospitals for diagnosis and treatment. Early diagnosis and prompt treatment with multidrug therapy are key to prevention. Many patients return to their homes completely free of symptoms and are able to resume normal lives. Cure has been most successful in cases that were diagnosed and treated at an early stage, especially among the young.

Among the public health measures used to prevent leprosy are the laws in most countries requiring that all cases be reported to the local authorities and that all discharged leprous patients be examined at six-month intervals. Most countries also refuse entry to immigrants known to be infected. In the United States, information about leprosy, as well as treatment, can be obtained from the Gillis Long Hansen's Disease Center, Carville, LA 70721, telephone 800-642-2477.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(lep'rŏ-sē), Negative or pejorative connotations of this word may render it offensive in some contexts. The term Hansen disease is generally preferable.
1. A chronic granulomatous infection caused by Mycobacterium leprae affecting the cooler body parts, especially the skin, peripheral nerves, and testes. Leprosy is classified into two main types, lepromatous and tuberculoid, representing extremes of immunologic response.
2. A name used in the Bible to describe various cutaneous diseases, especially those of a chronic or contagious nature, which probably included psoriasis and leukoderma.
Synonym(s): Hansen disease
[G. lepra, from lepros, scaly]
Farlex Partner Medical Dictionary © Farlex 2012


A chronic, mildly contagious disease of tropical and subtropical regions, caused by the bacterium Mycobacterium leprae, marked by lesions of the skin and mucous membranes and damage to peripheral nerves and other organs that, if untreated, can progress to disfigurement, lack of sensation, and blindness. Also called Hansen's disease.

lep·rot′ic (lĕ-prŏt′ĭk) adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


1. A chronic granulomatous infection caused by Mycobacterium leprae affecting the cooler body parts, especially the skin, peripheral nerves, and testes. Leprosy is a spectrum of diseases ranging in type from lepromatous to tuberculoid; these two types representing extremes of immunologic response.
2. A name used in the Bible to describe various cutaneous diseases, especially those of a chronic or contagious nature, which probably included psoriasis and leukoderma.
Synonym(s): Hansen disease.
[G. lepra, from lepros, scaly]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


a chronic disease characterized by mutilating and disfiguring lesions, with loss of sensation in fingers and toes, caused by infection with the bacterium Mycobacterium leprae. About three million people are affected worldwide, the condition being transmitted by contact between an affected area in the donor and skin abrasion in the recipient, although it is not highly contagious. Therapy with sulfone drugs over long periods can produce gradual improvement.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005


Gerhard Henrik Armauer, Norwegian physician, 1841-1912.
Fosdick-Hansen-Epple test - see under Fosdick
Hansen bacillus - a species that causes Hansen disease. Synonym(s): Mycobacterium leprae
Hansen disease - Synonym(s): leprosy

St. Giles,

patron saint of lepers, physically challenged people, paupers, and blacksmiths.
St. Giles disease - Synonym(s): leprosy
Medical Eponyms © Farlex 2012


Chronic granulomatous infection caused by Mycobacterium leprae affecting the cooler body parts, especially the skin, peripheral nerves, and testes; classified into two main types, lepromatous and tuberculoid.
Synonym(s): Hansen disease.
[G. lepra, from lepros, scaly]
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
'If the women affected by leprosy is not treated or delayed to get proper treatment, she will be exposed to disability.
The Health Minister said the National Leprosy Eradication Programme (NLEP) has achieved enormous success in leprosy control, particularly in the last four decades.
A 35-year-old male, laborer was referred to Marie Adelaide Leprosy Centre (MALC), by a dermatologist from Khyber-Pakhtunkhwa (KPK) province.
For his part, Coalition of Leprosy Advocates of the Philippines (CLAP) president Frank Onde said there is a global trend which shows the diminishing interest of the public in leprosy and its victims.
Sindh has the greatest number of leprosy patients in Pakistan,' said Mervyn Lobo, chief executive officer, Marie Adelaide Leprosy Centre, founded by the late Dr Ruth Pfau, at a press briefing marking World Leprosy Day at MALC office.
These views were expressed by leprosy experts including Mervyn Lobo, Chief Executive Officer, Dr Ali Murtaza, Director Training and Savio Pereira, Director Human Resources and Administration at a press briefing organised by MALC to mark World Leprosy Day at its head office, Karachi on Saturday.
Chapter 1 discusses the isolation of leprosy patients during the VOC (Vereenigde Oostindische Compagnie) rule during the seventeenth century at Angke, near Batavia along with Portuguese prisoners of war and South Indian slaves.
By the closing stages of March 2016, of 669 districts, 551 districts (82.36%) had prevalence of leprosy <1/10,000 population which is the target of eliminating it as a public health problem, 76 districts had prevalence between 1 and 2/10000, 39 districts had prevalence between >2 and 5/10,000, and only two districts had prevalence between 5 and 10.
Although leprosy is highly valued in China, new cases in Guizhou Province have not been significantly reduced in the past 20 years.
Leprosy primarily disturbs the skin and then the peripheral nerves.
Comparative cytomorphology of skin, lymph node, liver and bone marrow in patients with lepromatous leprosy. Cytopathology.
Leprosy is a chronic infectious disease caused by Mycobacterium leprae, characterized by varied clinical presentation.