Leprosy

Leprosy (LEH-pro-see) is a chronic ^* , infectious disease that damages the skin, peripheral nerves ^* , and mucous membranes ^* of the mouth, throat, and eyes. Leprosy also is known as Hansen disease.

What Is Leprosy?

His equipment was inadequate and his colleagues thought his theories were laughable. Still, Gerhard Henrik Armauer Hansen (1841-1912) spent day after day bent over his microscope, determined to prove that leprosy was caused by bacteria. And he did. In 1873 the Norwegian physician identified the rod-shaped bacterium Mycobacterium leprae (my-ko-bak-TEER-e-um LEH-pray) as the cause of the illness. Hansen's discovery was immensely valuable in the treatment of leprosy, and it was a scientific milestone—the first proof that bacteria could cause human disease. Today, the use of the word "leper" is considered insulting, because it defines a person by the disease he or she has. Many advocates for people with leprosy prefer to call it Hansen disease.

The name paucibacillary (paw-sih-BAH-sih-lair-e) Hansen disease comes from the Latin word pauci, meaning few, and is used to describe a mild form of leprosy. Paucibacillary Hansen disease begins in the peripheral nerves and spreads to the skin, causing patches of skin to become numb and hypopigmented, which means that the skin has lost its coloring and appears white. Multibacillary (mul-tie-BAH-sih-lair-e) Hansen disease is a more severe form of the disease. Multibacillary Hansen disease also causes skin lesions (LEE-zhuns), or patches of damaged tissue; nodules, or lumps; and thickening of the skin. Without treatment, this type of leprosy can worsen over time, resulting in severe skin and tissue damage and disfigurement.

How Common Is Leprosy?

Throughout human history leprosy has caused untold suffering. Even after Hansen's groundbreaking discovery, the disease remained unchecked in many parts of the world. In 1991, the World Health Organization (WHEO) began a global campaign to reduce the number of cases of leprosy. A decade later the organization announced that it had reached its goal and estimated that there were at that time 600,000 to 750,000 cases of leprosy worldwide. The disease is most common in tropical and subtropical regions, and in 2001, it remained a particular problem in Brazil, India, Madagascar, Mozambique, Nepal, and Myanmar. Leprosy is most common in densely populated areas with poor sanitation and health care, and children are at greater risk than adults of getting the disease. In the United States about 100 cases are reported each year, many of them in people who have recently immigrated.

Is the Disease Contagious?

Leprosy is contagious but does not spread easily. Researchers believe that Mycobacterium leprae is transmitted from person to person via respiratory droplets, bits of moisture that leave the mouth or nose when a person laughs, talks, sneezes, or coughs. Most people seem to have a natural immunity ^* that enables them to resist the disease. Of those in whom leprosy is diagnosed, most have had prolonged and close contact with someone who has an active infection. Once a person with leprosy has been taking medication for 3 or 4 days, the disease is no longer active or contagious.

What Are the Signs and Symptoms?

Leprosy begins as an infection in the nerve endings and spreads gradually; the skin near the infected nerves may become numb and hypopigmented. In severe cases, these skin lesions become wider and thicker. The muscles in the hands and feet can become weak or paralyzed (unable to move) because of damage to the peripheral nerves. That loss of sensation can lead to accidental injury, because a person loses the withdrawal reflex that helps protect against injury from hot or sharp objects. Left unchecked, the most severe form of the disease can progress, producing large, disfiguring nodules and enlarged facial features that give a person the lionlike appearance associated with severe leprosy.

How Is Leprosy Diagnosed?

Leprosy is not difficult to diagnose once it is suspected. A procedure in which a tiny piece of skin is scraped or cut away and then examined usually reveals the presence of Mycobacterium leprae in the multibacillary form of leprosy. (The bacteria may not be found using this method in milder, paucibacillary disease.) The procedure can be done quickly and relatively painlessly in a doctor's office or clinic. It is an important part

of the diagnosis, because in the early stages of the disease leprosy lesions look very much like skin damage caused by other neurocutaneous ^* diseases. The presence of the characteristic lesions, accompanied by a history of living in areas where the disease is common, is what usually causes doctors to suspect the diagnosis.

Can Leprosy Be Treated?

Early diagnosis and treatment are key to stopping the spread of leprosy to other people and preventing long-term damage to the patient. Doctors most often prescribe multidrug therapy (MDT), combining two or three drugs that kill the bacteria: dapsone (DAP-sone), rifampicin (rye-FAM-pih-sin), and clofazimine (klo-FAY-zuh-meen). The MDT approach has been preferred since the early 1980s, when researchers noticed that the bacterium was becoming resistant to some treatments. Patients may take the drugs for as little as 6 months or as long as 2 years. Patients who have become disfigured or who experience disabilities may need surgery to correct these problems.

What Are the Complications and Course of Leprosy?

With MDT, paucibacillary Hansen disease can be cured within 6 to 12 months and multibacillary Hansen disease within 2 years. Untreated, leprosy can cause blindness, permanent nerve damage, and deformity. People may lose the use of their hands or feet, because, over time, the decreased sensation may result in repeated injuries to the limbs.

How Can Leprosy Be Prevented?

Despite centuries in which people with leprosy were vilified, shunned, and even isolated in far-off "leper colonies," there is no need to separate people with leprosy from the rest of society to avoid the spread of infection. MDT treatment is more effective and far more humane, and it has been determined that leprosy is much less contagious than once was believed. Hand washing, disinfection, and monitoring of close contacts are recommended to help prevent the spread of the disease.