Leprosy is an infectious disease characterized by skin lesions and nerve damage. Mainly affecting the peripheral nerves (those outside the brain and spinal column), skin, eyes, testicles and nose, it has a long incubation time. It is usually between three to eight years before the disease is evident. Leprosy is quite rare. It is primarily seen in tropical and subtropical Asia, Africa, South America and Central America. In the United States, most cases involve immigrants from developing countries. It may occur at any age and in any race.

There is a wide spectrum of findings in leprosy. The two major polar forms of leprosy are lepromatous leprosy and tuberculoid leprosy. Lepromatous leprosy is characterized by many skin lesions that are vague and difficult to distinguish from normal skin, as well as weakness and paralysis affecting both sides of the body equally. Tuberculoid leprosy is characterized by fewer, more prominent skin lesions and loss of feeling, weakness and paralysis affecting one side of the body more than the other. Between these two forms is borderline leprosy. Another form, indeterminate leprosy, may be mild with few or no skin lesions.

Leprosy is caused by particular bacteria (Mycobacterium leprae). The spread of the disease requires a contagious patient, a person susceptible to the disease and close or long-term contact between the two. Patients undergoing treatment are not contagious and most people are immune to the bacteria.

Skin lesions in leprosy may be reddened or hypopigmented (lighter than the surrounding skin). There is often a reduced or lack of sensitivity to temperature, touch and pain within the lesion and possibly in the hands and feet. Nerve damage can lead to deformities, such as a claw hand. In advanced cases, the nose may erode and collapse. Inflammatory reactions may also be frequent during the course of the disease and its treatment.

The diagnosis of leprosy relies upon the patient’s medical history, a physical examination and a skin biopsy from a lesion. Laboratory examination of the biopsy may detect the presence of the bacteria that causes leprosy or other characteristic changes.

Leprosy treatment relies on a multi-drug strategy employing a combination of various antibiotics. Active treatment may last from six months to two years and the patient is closely observed for up to five years after treatment ends. Patients are considered cured after the completion of the treatment regimen.

Leprosy is a chronic (long-term), infectious disease characterized by skin lesions and nerve damage. It is very rarely fatal, but may be deforming, disabling and stigmatizing. The disease primarily damages the peripheral nerves (those outside the brain and spinal column), skin, eyes, testicles and mucous membranes of the nose. Leprosy has a very long incubation time, ranging from a single year to more than 30 years, although the incubation of most cases is from three to eight years.

Leprosy is caused by an infection by the bacteria Mycobacterium leprae, which multiply very slowly. Because they require a temperature of around 95 degrees Fahrenheit (35 degrees Celsius) to grow, they prefer the cooler regions of the body (e.g., skin, nose, ear lobes, testicles).

For centuries, leprosy was a greatly feared, misunderstood and highly stigmatized disease. It is mentioned in texts as old as the Bible, although many biblical cases of “leprosy” may have actually been other conditions (e.g., psoriasis, vitiligo). People infected with the disease were avoided and often quarantined to leper colonies.

The bacteria that cause leprosy were discovered in 1873 by Gerhard Armauer Hansen, a Norwegian scientist. As a result, leprosy is also called Hansen disease or Hansenosis.

Leprosy occurs very rarely. It is most often seen in tropical and subtropical regions today. This is likely related to a lower standard of living and poorer hygiene available in the developing countries where the disease occurs rather than to the tropical climate. The disease is most common in Brazil, India, Indonesia, Madagascar, Mozambique, Myanmar, Nepal and Nigeria.

In the United States, most cases of leprosy involve immigrants from developing countries. These cases are most common in areas with high immigrant populations. Leprosy may occur at any age and in any race. However, it is rarely seen in infants. Men are affected somewhat more often than women, especially with the more extreme lepromatous form.

Complications of leprosy include bacterial skin infections, ulcers and amputation of fingers and toes due to damage caused by the lack of sensation. Tuberculosis frequently accompanies the disease, particularly in untreated lepromatous form. Amyloidosis (buildup of a particular protein in the tissues) may lead to death in advanced, untreated cases.

The form of leprosy a person develops depends on his or her immune response to the infection. In most cases, people infected with Mycobacterium leprae never develop signs or symptoms of leprosy because their immune system effectively attacks the microorganism. Severe forms of the disease develop in people whose immune response is less effective.

The state of a person’s immune system also affects progress of the disease. Leprosy can remain in one form, improve to a less severe form or worsen to a more debilitating form.

There are two principle forms of leprosy. These are:

• Lepromatous leprosy (multibacillary leprosy). Occurs in patients with decreased function of the immune system. This form is characterized by many skin lesions and the symmetrical (occurs on both sides of the body equally) involvement of the peripheral nerves (nerves outside the brain and spinal cord). Nerve involvement includes lack of feeling, muscle weakness and paralysis. Many of the bacteria that cause the disease can be found in the skin and nasal mucus. This is the most contagious form of leprosy. Unlike other forms of leprosy, lepromatous leprosy never reverts to a less debilitating form.
  
  
• Tuberculoid leprosy (paucibacillary leprosy). Occurs in patients with normal immune function. This form is characterized by greater nervous involvement that is typically asymmetrical (occurs more on one side of the body than the other). Lack of feeling is common and skin lesions are few or absent. Few or no bacteria can usually be found in the lesions.

Borderline leprosy (dimorphous leprosy) falls between these two variations. The signs, symptoms and findings of this form may fall anywhere in between lepromatous and tuberculoid leprosy, but it often leans toward one or the other. It can also become more serious, turning into either form if the body does not fight off the infection.

Indeterminate leprosy is an often very mild form with few or no skin lesions. It often resembles tuberculosis and frequently resolves on its own. However, the condition may progress to a more severe form in patients with weakened immune systems. Bacteria are found in very small numbers, if at all, in lesions.

Leprosy is caused by an infection by the bacteria Mycobacterium leprae. The infection is believed to spread from nasal mucus (e.g., airborne droplets). It can also enter through broken skin, but it cannot be contracted simply by touching an infected person. The bacteria can live up to seven days in dried secretions.

Most people are not susceptible to the bacteria, and short-term exposure will usually not result in infection. When infection occurs, a single lesion will often develop after the bacteria incubate for several years and will often heal on its own.

People susceptible to leprosy often have close, long-term contact with an infected person (e.g., a family member). An impaired immune system (or one that is not resistant to the Mycobacterium leprae bacteria) may also be a risk factor.

Children appear more susceptible than adults. Infants are particularly at risk of contracting the disease from infected mothers, particularly if the mother is untreated and has the lepromatous form. Some evidence suggests that it may be possible to contract from infected soil, armadillos or biting insects, but this has not been proven.

The onset of leprosy is very gradual and the disease may go unrecognized for years. In fact, it may take as long as 30 years for symptoms to develop. This can make it difficult for a physician to determine where and when the disease was contracted.

It primarily affects the cooler areas of the body (e.g., nerves near the skin surface, skin, mucous membranes in the nose, upper respiratory tract, testicles).

Skin lesions may be erythematous (reddened) or hypopigmented (lighter than the surrounding skin). Hypopigmentation is particularly likely in people with darkly pigmented skin. The lesions are often lacking in feeling, with reduced sensitivity to temperature, touch or pain, and they generally do not heal on their own. Sores frequently develop on the soles of the feet.

In most people, a sensation of numbness is the first symptom to develop. In fact, numbness may develop years before skin lesions occur.  Nerve infection typically causes loss of feeling, especially in the hands, feet, arms and legs, and also muscle weakness. In some cases, the nerves may be enlarged or painful. Nerve involvement may lead to numerous deformities, including claw hand, foot drop, claw toes, ptosis (drooping of the upper eyelid) and lagophthalmos (inability to close the eye).

Nasal infection may lead to a chronically stuffy nose and, in the rare occurrence of advanced cases, deformity including tissue erosion and collapse of the nose. Eye tissues may become inflamed and laryngeal (voice box) involvement may lead to hoarseness. Men with leprosy may experience erectile dysfunction and infertility due to a reduction in testosterone and sperm production in the testicles.

The different forms of leprosy have specific signs and symptoms. These include:

• Lepromatous leprosy. Numerous symmetrical, erythematous, poorly-defined macules, papules, nodules and plaques (raised patches) form in widespread distribution, particularly on the face, buttocks and lower extremities. Sensation in these lesions may not be affected. Patches of skin become thickened and lumpy. Eyelashes and eyebrows may be lost and thickening over the forehead and flattening of the bridge of the nose may contribute to a characteristic “leonine” appearance. Both earlobes may become thick and bulbous and scaling may form over the lower extremities.
  
  
• Tuberculoid leprosy. Few (less than five) or no skin lesions form. Those that do form are often hypopigmented and slightly raised plaques that are localized, asymmetrical and well-defined, with sharp borders. The lesions may also become dry and hairless. Sensation in the lesions is typically completely absent and nerve involvement is often widespread but asymmetrical. Loss of bone, especially in the extremities, may occur.
  
  
• Borderline leprosy. Signs and symptoms may vary from anywhere among the spectrum between lepromatous and tuberculoid leprosy.
  
  
• Indeterminate leprosy. Few (less than five) often hypopigmented macules appear. These are not always well defined and sensation within them is usually impaired, but not absent.

Leprosy is usually a slow disease occasionally interrupted by phases of active disease worsening (called reactions). Sudden reactions may cause tissues to become inflamed (red, swollen and hot). Possible causes of these reactions include medication (e.g., antimicrobial drugs), pregnancy, infection and stress. There are two general types of reaction, including:

• Type 1 (reversal) reactions. Most likely due to changes in the immune system. These reactions may cause neuritis (inflammation of a nerve), increased inflammation in established lesions, acute nerve pain or tenderness, loss of nerve function and the formation of new lesions.
  
  
• Type 2 reactions. Due in part to antibody activities against the bacteria. These occur in the more extreme lepromatous and borderline forms of leprosy and can occur while a patient is undergoing treatment. They may cause:
  
  
• Inflamed blood vessels (vesticulitis)
• Fever
• Myalgia (muscle pain)
• Arthralgia (joint pain)
• Malaise (general ill feeling)
• Edema (swelling)
• Iridocyclitis (inflammation of eye tissue)
• Orchitis (inflammation of the testicles)
• Lymphadenitis (swollen lymph nodes)
• Red, tender nodules on the skin

The diagnosis of leprosy is provided by a physician based on the patient’s medical history, a physical examination and a skin biopsy. The medical history focuses on any exposure the patient may have had to the disease, including visiting areas of the world where the disease frequently occurs.

During the physical examination, the physician examines any skin lesions and investigates any muscle or nerve problems, such as muscle atrophy (weakness) or decreased sensation to temperature, touch or pain. The physician may feel certain areas of the skin for enlarged superficial nerves.

Samples of skin for examination are typically taken from within a lesion. Smears may be taken from lesions on the ears, elbows or knees. A mucous sample from inside the nose may also be taken. Laboratory examination of these samples may detect the presence of the bacteria that cause the disease or other characteristic changes. In most cases, multiple samples from many different lesions will be needed.

Conditions that may be mistaken for leprosy include:

• Psoriasis. A skin disease characterized by red patches covered in silvery scales. Some lesions of psoriasis may resemble those of leprosy.
  
  
• Sarcoidosis. A rare disease characterized by protein deposition in various body tissues. Skin involvement may resemble leprosy.
  
  
• Cutaneous T-cell lymphoma. Cancer of certain cells in the skin. Lesions may resemble those characteristic of leprosy.

Leprosy was thought for many years to be incurable, but this is no longer the case. Patients are now considered cured after completing the treatment regimen. Furthermore, after treatment has begun, the patient is no longer infectious to others.

Early diagnosis and treatment is important. Left untreated, the disease can cause significant damage to the skin, nerves, limbs and eyes. Neurological (nerve) damage may be difficult to repair, although physical therapy may help. In some cases, surgery may be required to restore nerve function. Though skin lesions typically clear up within a year of therapy, reconstructive surgery may be required for advanced cases where deformity occurs. The management of the disease is complex and may require expert consultation. There are several centers for the care and treatment of the disease located throughout the United States.

Leprosy is treated with multiple medications. The primary drugs used are antibiotics (e.g., dapsone, rifampin, clofazimine). A combination of two or more antibiotics may be recommended. These and most other drugs used in therapy may pose some risks to the fetus in pregnancy but are generally considered safe. Active treatment may last from six months to two years. The patient is closely observed for up to five years after treatment ends. Typically, there are few relapses.

Reactions are treated when they arise. Type 1 (reversal) reactions are treated with oral corticosteroids. Type 2 reactions are treated with corticosteroids and, at times, thalidomide. This drug is not safe for use in women who are or may become pregnant.

Preventing the spread of leprosy involves early diagnosis and treatment of those who are infected. Family members and others who have had close, long-term contact with a leprosy patient should have annual examinations for five or more years after last contact with the infected person.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about leprosy:

1. Do my symptoms indicate leprosy?
   
   
2. What tests will you use to determine if I have leprosy?
   
   
3. How could I have contracted leprosy?
   
   
4. What form of leprosy do I have?
   
   
5. What dangers does leprosy pose to my overall health?
   
   
6. Do you have any experience in treating leprosy?
   
   
7. Where is the nearest center for the specialized treatment of leprosy?
   
   
8. What are my treatment options?
   
   
9. At what point will I be considered cured?
   
   
10. May I have infected the members of my household?
    
    
11. For how long after I begin treatment may I remain infectious?