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Leishmaniasis +lEsh-mu-!nI-u-sus

by Richard D. Pearson, MD

Leishmaniasis is caused by several species of Leishmania protozoa. Leishmaniasis includes disorders that affect certain internal organs, those that affect the skin and cause painless bumps or sores, and those that affect mucous membranes of the nose and mouth.

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

  • People may have mild or no symptoms or have bouts of fever, weight loss, fatigue, skin sores that may cause scars or severe disfigurement, or sores in the nose, mouth, or throat.

  • 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 the species of protozoa and the geographic location.

Forms of leishmaniasis

There are three forms. Each affects a different part of the body.

  • 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.

  • 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. This form begins with a skin sore. The parasites are thought to spread from the sore through the lymph and blood vessels to the mucous membranes. Only certain species of Leishmania protozoa cause this form.

Transmission of leishmaniasis

Tiny infected sand flies spread the protozoa 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.

People with a weakened immune system, particularly those with AIDS, are more susceptible to leishmaniasis.

Symptoms of Leishmaniasis

Visceral leishmaniasis causes mild symptoms, which may not be noticed. The disorder may occur suddenly but usually progresses gradually over weeks to months after infection. 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. If visceral leishmaniasis progresses, it is usually fatal unless it is treated.

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, skin sores develop in people who were infected in some areas of the world. The sores typically last a few months in people who were infected in East Africa but last years in people who were infected in India. These sores may contribute to the spread of infection.

In cutaneous leishmaniasis , the first symptom is usually a 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. 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 typically heal on their own after several months but may persist for years. They leave permanent scars similar to those due to burns. Occasionally, sores appear on skin all over the body.

In mucosal leishmaniasis , symptoms begin with a skin sore that heals on it own. Sores 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, these sores may cause severe disfigurement.

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

Diagnosis of Leishmaniasis

  • Tests on a sample of the infected tissue

  • Sometimes blood tests

Doctors diagnose leishmaniasis by taking samples of the infected tissue. Microscopic examination, culture, or molecular tests to check for 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 AIDS. Blood tests for antibodies are not helpful in diagnosing cutaneous leishmaniasis.

Prevention of Leishmaniasis

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)

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

  • 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 of Leishmaniasis

  • 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

Visceral leishmaniasis

The drug of choice in the United States and other developed countries is

  • Liposomal amphotericin B (an antifungal drug) given by vein

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

In Latin America and Africa, drugs that contain antimony (such as sodium stibogluconate or meglumine antimonate), given by injection, are often used. These drugs may cause nausea, vomiting, fatigue, and heart problems (which require stopping the drug). If the protozoa are resistant to drugs that contain antimony (common in India), miltefosine can be used to treat people infected in India or adjacent areas of Asia or in Africa.

Transfusions or antibiotics to treat concurrent bacterial infections may be needed. Adequate nutrition is also important because people with visceral leishmaniasis are often malnourished.

Cutaneous leishmaniasis

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

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

  • Heat or cold therapy applied to sores

  • Paromomycin ointment (an amebicide) applied topically to sores

  • Outside the United States, sodium stibogluconate injected into the sore

For several large or disfiguring sores, for people with a weakened immune system, or for sores due to Leishmania species that can cause mucosal leishmaniasis, treatment usually includes drugs given by mouth or injection (systemically), such as the following:

  • Liposomal amphotericin B

  • Miltefosine

  • Sodium stibogluconate

  • Fluconazole (an antifungal drug)

Mucosal leishmaniasis

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

  • Liposomal amphotericin B

  • Amphotericin deoxycholate

  • Miltefosine

  • Sodium stibogluconate

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.

For people with AIDS

Treatment with antiretroviral drugs can improve a person's immune response against Leishmania and reduce the risk of recurrence.

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