Leishmaniasis is caused by several species of Leishmania protozoa. Leishmaniasis includes disorders that affect internal organs and those that affect the skin and sometimes mucous membranes of the nose and mouth, causing bumps or sores.
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 at birth, or through sexual contact.
The form that affects internal organs (visceral leishmaniasis, or kala-azar) 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. The form that affects the skin (cutaneous leishmaniasis) occurs in southern Europe, Asia, Africa, Mexico, and Central and South America. Outbreaks have occurred among US military personnel training in Panama or serving in Iraq or Afghanistan. Occasionally, travelers to affected areas develop the disorder. People with a weakened immune system, particularly those with AIDS, are more susceptible to leishmaniasis.
Symptoms and Diagnosis
Usually, symptoms of visceral leishmaniasis are mild and may not be noticed. The disorder progresses in a minority of infected people. In them, symptoms typically develop gradually over weeks to months. People may have irregular bouts of fever. They may lose weight, vomit, have diarrhea, and be generally tired. The liver, spleen, and lymph nodes enlarge. The number of blood cells decreases, causing anemia and making people more susceptible to other infections. Without treatment, 80 to 90% of people who develop symptoms die within 1 to 2 years. After treatment, skin sores develop in some people and may last a few months to several years.
In cutaneous leishmaniasis, the first symptom is a bump at the site of a sand fly bite. It appears after several weeks or months and contains protozoa. As the infection spreads, more bumps may appear. The initial bump slowly enlarges and becomes an open sore, which may ooze or form a scab. The sores are painless and cause no other symptoms unless another infection develops in them. The sores typically heal on their own after several months but may persist for years. They leave scars similar to those due to burns. Scars may be permanent. Sometimes after the skin sores heal, sores appear on mucous membranes in the nose and mouth. The first sign may be a stuffy nose or nosebleeds. These sores may cause severe disfigurement. Occasionally, sores appear on skin all over the body, causing a condition that resembles leprosy.
In people with AIDS, leishmaniasis often recurs.
Doctors diagnose leishmaniasis by taking a sample of the infected tissue. The samples may be analyzed to determine whether the protozoa they contain can infect the mucous membranes. Blood tests can be used to confirm visceral leishmaniasis in people with symptoms.
Prevention and Treatment
Prevention begins with treating infected people and trying to prevent sand fly bites. People who are treated are less susceptible to reinfection by the same species of Leishmania. Insect repellents containing DEET (diethyltoluamide) provide protection. Insect screens, bed nets, and clothing are more effective if treated with insecticides such as permethrin or pyrethrum because the tiny flies can pass through them otherwise.
Drugs used to treat the infection depend on the species and the geographic location.
For visceral leishmaniasis, liposomal amphotericin B given by vein is the drug of choice in the United States and other developed countries. Amphotericin B deoxycholate is also effective but has more side effects. In Latin America and Africa, drugs that contain antimony (such as sodium stibogluconate or meglumine antimonate) 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, which is not available in the United States, can be used. Transfusions or antibiotics to treat concurrent bacterial infections may be needed. Adequate nutrition is also important because undernutrition can worsen the disorder.
Treatment of cutaneous leishmaniasis depends on the extent of the disease and the possibility of spread to mucous membranes. Antimony drugs are often used, particularly if spread to mucous membranes is possible. Other drugs used include fluconazole or itraconazole, usually taken by mouth, and paromomycin ointment. Widespread sores are difficult to treat. Reconstructive surgery may be needed if the nose or face is disfigured, but surgery should be delayed 6 to 12 months after treatment, when the risk of recurrence is less likely.
Last full review/revision March 2007 by Richard D. Pearson, MD