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Leishmaniasis ˌlēsh-mə-ˈnī-ə-səs

By Richard D. Pearson, MD, Emeritus Professor of Medicine, University of Virginia School of Medicine

Leishmaniasis is caused by several species of Leishmania protozoa. Leishmaniasis includes several disorders that affect the skin, the mucous membranes of the nose and mouth, or internal organs including the liver, spleen, and bone marrow.

  • Leishmania protozoa are usually spread through the bite of infected sand flies.

  • People may have mild or no symptoms or have skin sores that result in scars or sores in the nose, mouth, or throat that can lead to severe disfigurement or have fever, weight loss, and fatigue, depending on which part of the body is affected.

  • Doctors diagnose the infection by analyzing samples of infected tissue or doing blood tests.

  • Using insect repellents and bed nets and clothing treated with insecticides helps prevent sand fly bites.

  • Drugs used to treat the infection depend on what the person's symptoms are, which species of Leishmania is causing the infection, and where the infection was acquired.

Leishmaniasis occurs in scattered areas throughout the world.

Transmission of leishmaniasis

Tiny infected sand flies spread Leishmania when they bite people or animals, such as dogs or rodents. Rarely, infection is spread in blood transfusions, through injections with a needle previously used by an infected person, from mother to child before or at birth, or, very rarely, through sexual contact.

Forms of leishmaniasis

There are three forms of leishmaniasis. Each affects a different part of the body. After the protozoa enter the body through a bite in the skin, they may remain in the skin or spread to the mucous membranes of the nose and mouth or to internal organs.

  • Cutaneous leishmaniasis affects the skin. It occurs in southern Europe, Asia, Africa, Mexico, and Central and South America. Outbreaks of leishmaniasis have occurred among US military personnel training in Panama or serving in Iraq or Afghanistan. Occasionally, travelers to affected areas develop the disorder.

  • Mucosal leishmaniasis affects the mucous membranes of the nose and mouth, causing sores and destroying tissue. This form begins with a skin sore. The parasites spread from the skin through the lymph and blood vessels to the mucous membranes. Symptoms of mucosal leishmaniasis can develop while the skin sore is present or months to years after the sore heals.

  • Visceral leishmaniasis (kala-azar) affects the internal organs, particularly the bone marrow, lymph nodes, liver, and spleen. It occurs in India, Africa (particularly the Sudan), Central Asia, the area around the Mediterranean, South and Central America, and infrequently China. Parasites spread from the skin to the lymph nodes, spleen, liver, and bone marrow. Only a few infected people develop symptoms. Children are more likely to have symptoms than adults, and the disease is more likely to progress in people with a weakened immune system, particularly those with AIDS, than in people with a healthy immune system.

Symptoms

In cutaneous leishmaniasis, the first symptom is usually a well-defined bump at the site of a sand fly bite. It typically appears after several weeks or months and contains parasites. As the infection spreads, more bumps may appear near the initial bump. The initial bump slowly enlarges and often becomes an open sore, which may ooze or form a scab. The sores are usually painless and cause no other symptoms unless a bacterial infection develops in them. The sores eventually heal on their own after several months but may persist for more than a year. They leave permanent scars similar to those due to burns. Rarely, sores appear on skin all over the body,more often in people with AIDS.

In mucosal leishmaniasis, symptoms begin with a skin sore that heals on it own. Sores and tissue destruction may appear on mucous membranes inside the nose, mouth, or throat while the skin sore is present or months to years after it heals. The first sign may be a stuffy nose, a discharge from the nose, or nosebleeds. Over time, people may be severely disfigured.

Visceral leishmaniasis may start suddenly but usually develops gradually over weeks to months after the infecting sand fly bite. People may have irregular bouts of fever. They may lose weight, have diarrhea, and be generally tired. The liver, spleen, and sometimes lymph nodes enlarge. The number of blood cells decreases, causing anemia and making people more susceptible to other infections. Without treatment, visceral leishmaniasis can result in death.

People who respond to treatment and those who are infected but do not have symptoms are unlikely to have symptoms later unless their immune system is weakened (for example, by AIDS or by drugs that are used to suppress the immune system, such as those used to prevent rejection of a transplanted organ).

After treatment of visceral leishmaniasis, patches or lumps (nodules) may appear on the skin as other symptoms of visceral leishmaniasis go away. When sand flies bite people who have these areas of abnormal skin, the flies become infected and can thus spread the infection. Whether patches and lumps appear and how long they last depend on where people were infected:

  • The Sudan (located south of the Sahara) in Africa: The patches and lumps typically remain a few months to a year.

  • India and nearby countries: The patches and lumps can last years.

  • Southern Europe, North Africa, the Middle East, and Latin America: Patches and lumps do not appear on the skin after treatment of visceral leishmaniasis.

In people with AIDS, visceral leishmaniasis often recurs, and cutaneous leishmaniasis can cause sores all over the body.

Diagnosis

  • Examination of and tests on samples of infected tissue

  • Blood tests for visceral leishmaniasis

Doctors diagnose leishmaniasis by taking samples of the infected tissue in people who have skin sores and may have cutaneous leishmaniasis or by taking samples of blood, bone marrow, liver, or spleen in people who may have visceral leishmaniasis. Microscopic examination, culture, and tests to check for the genetic material (DNA) of Leishmania may be done to determine whether the samples contain Leishmania.

Blood tests to detect antibodies against Leishmania can sometimes help doctors diagnose visceral leishmaniasis. (Antibodies are proteins produced by the immune system to help defend the body against attack, including that by parasites.) However, results of antibody tests may be negative, particularly in people with a weakened immune system, such as those with AIDS. Blood tests for antibodies are not helpful in diagnosing cutaneous leishmaniasis.

Prevention

Leishmaniasis prevention begins with preventing sand fly bites.

For people who travel to or live in areas where the infection is common, the following can help:

  • Using insect repellents containing DEET (diethyltoluamide) on exposed skin

  • Using insect screens, bed nets, and clothing that are treated with insecticides such as permethrin

  • Wearing long-sleeved shirts, long pants, and socks, with the shirt tucked into the pants

  • Avoiding outdoor activities from dusk to dawn, when sand flies are most active

Treatment

  • Various drugs, depending on several factors

  • If mucosal leishmaniasis causes disfigurement, reconstructive surgery

Drugs used to treat leishmaniasis depend on the following:

  • The form of the disease

  • The Leishmania species involved

  • The geographic location where the person was infected

  • The likelihood that the Leishmania species is susceptible to treatment

  • The status of the person's immune system

  • The route of drug administration and potential side effects

Cutaneous leishmaniasis

Treatment of cutaneous leishmaniasis depends on the extent of the disease and the species causing the infection.

For small, uncomplicated sores due toLeishmania species that do not cause mucosal leishmaniasis, treatment includes

  • Heat or cold therapy applied to sores

  • Paromomycin ointment (an amebicide) applied topically to sores

  • Sodium stibogluconate injected into the sore

  • A drug used to treat leishmaniasis (antileishmanial drug—see below)

Paromomycin ointment and sodium stibogluconate for injection into the skin are not available in the United States. If a sore has started to heal on its own, doctors may observe it rather than treat it. If it continues to heal, no treatment is needed.

Treatment usually includes an antileishmanial drug if people have any of the following:

  • Several large or disfiguring sores

  • A weakened immune system

  • Sores due to Leishmania species that can cause mucosal leishmaniasis

Antileishmanial drugs include

  • Miltefosine

  • Liposomal amphotericin B (typically used to treat fungal infections)

  • Amphotericin B deoxycholate (typically used to treat fungal infections)

  • Sodium stibogluconate

  • Meglumine antimonate

All of these drugs are given by injection (systemically), except miltefosine, which is given by mouth. Miltefosine cannot be given to pregnant women because it may cause birth defects.

Mucosal leishmaniasis

For mucosal leishmaniasis, which treatment is best is unclear. Options include

  • Miltefosine

  • Liposomal amphotericin B

  • Amphotericin B deoxycholate

  • Sodium stibogluconate

  • Meglumine antimonate

Reconstructive surgery may be needed if the nose or face is disfigured, but surgery should be delayed 12 months after treatment, when the risk of recurrence is less likely.

Visceral leishmaniasis

The drugs of choice are

  • Liposomal amphotericin B

  • Miltefosine

Other forms of amphotericin B may also be effective, but they have not been studied as thoroughly as liposomal amphotericin B.

In Latin America and Africa, drugs that contain antimony (such as sodium stibogluconate or meglumine antimonate), given by injection, may be used because the Leishmania species that cause visceral leishmaniasis in these areas are not resistant to these drugs. In India and nearby countries, Leishmania species are commonly resistant to drugs that contain antimony. Drugs that contain antimony may cause nausea, vomiting, fatigue, and heart problems (which require stopping the drug).

Supportive measures, such as adequate nutrition, blood transfusions, or antibiotics to treat concurrent bacterial infections, may be needed.

For people with AIDS

Liposomal amphotericin B or miltefosine is used to treat visceral leishmaniasis in people with AIDS. In addition, treatment of AIDS with antiretroviral drugs can improve a person's immune responses against Leishmania and reduce the risk of recurrence.

In some people with AIDS and recurrent visceral leishmaniasis, liposomal amphotericin B is given at regular intervals after initial treatment to prevent additional recurrences.

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