Leishmaniasis
Leishmaniasis, also known as kala-azar in its visceral form, is a parasitic disease caused by protozoan parasites from the genus Leishmania. This disease affects approximately 700,000 to one million individuals annually, predominantly in subtropical and tropical regions worldwide, with a significant number of at-risk populations. Transmission occurs through the bites of sandflies, although the parasites can also spread through blood transfusions and shared needles. Symptoms can vary based on the form of the disease; skin infections may lead to ulcers, while visceral leishmaniasis can cause severe symptoms such as fever, weight loss, and enlargement of the spleen and liver, particularly in children and adults alike.
Diagnosis typically requires detecting the parasite in bodily fluids, and while the disease can be chronic, treatment primarily involves antimony-containing medications, with options like amphotericin B and pentamidine for resistant cases. Although high cure rates are achievable, relapses can occur, and surgery may be necessary for disfiguring skin lesions. Preventive measures focus on avoiding sandfly bites through the use of insect repellent and protective clothing, as no vaccines are available. Leishmaniasis remains a global health concern, particularly for military personnel in certain regions.
Leishmaniasis
ALSO KNOWN AS: Kala-azar
ANATOMY OR SYSTEM AFFECTED: Bones, immune system, lymphatic system, skin
DEFINITION: A complex of diseases caused by protozoan parasites of the genus Leishmania.
CAUSES: Transmission of protozoa through sandflies
SYMPTOMS: Skin infection and ulcers; vomiting, fever, abdominal discomfort, diarrhea, weight loss, and cough in children; also fatigue, weakness, and appetite loss in adults; darkening, dry, and flaky skin; thinning hair; enlargement of spleen, liver, and lymph nodes
DURATION: Often chronic
TREATMENTS: Medications containing the mineral antimony (meglumine antimonite, stibogluconate) and sometimes amphotericin B, pentamidine, flagyl, and allopurinol; plastic surgery to correct disfigurement; removal of spleen
Causes and Symptoms
Leishmaniasis, also known as kala-azar in its visceral form, is a parasitic disease that strikes about 700,000 to one million persons each year. At least 350 million persons, from more than ninety subtropical and tropical countries around the world, are at risk of contracting the disease. Leishmaniasis has received more attention among United States’ medical authorities because of the risk of contracting the disease faced by US military personnel in Southwest Asia, including Iraq, and Central Asia, including Afghanistan. Leishmaniasis may be a contributor to the complex of illnesses called Gulf War syndrome reported from veterans of the first Persian Gulf War in 1991.
Leishmaniasis is caused by any of more than twenty species of the protozoan Leishmania. They are transmitted by the bites of sandflies, small bloodsucking insects in the subfamily Phlebotominae. The parasite may also be transmitted by blood transfusion, sharing of needles by intravenous drug abusers, and other modes not requiring the bite of a sandfly. Humans are one of many mammalian hosts of these parasites. Infection can cause skin disease, called leishmaniasis. Leishmania can also affect the mucous membranes, frequently resulting in ulcers, or cause disease called visceral leishmaniasis, which is often fatal. Infection in children is usually sudden, with symptoms including vomiting, fever, abdominal discomfort, diarrhea, weight loss, and cough. Adults suffer from similar symptoms, but they may be accompanied by nonspecific symptoms such as fatigue, weakness, and loss of appetite. The skin may become darker, dry, and flaky, and the may begin to thin. Other signs include an enlarged spleen, liver, and lymph nodes.
Diagnosis is based on demonstration of the in pulp, lymph nodes, liver, or peripheral blood. Species of Leishmania cannot be differentiated morphologically. They are distinguished on the basis of the disease produced, the host and its immune response, and geographical distribution.
Treatment and Therapy
Compounds containing the mineral antimony are the principal medications used to treat leishmaniasis. These compounds include meglumine antimonite and sodium stibogluconate. When these drugs are ineffective, other antiprotozoan medications may be utilized, including amphotericin B, pentamidine, flagyl, and allopurinol. With mucocutaneous leishmaniasis, plastic surgery may be needed to correct the disfigurement caused by destructive facial lesions. Removal of the spleen may be required in drug-resistant cases of visceral leishmaniasis. Relapse may occur and infection may persist despite treatment.
Perspective and Prospects
Cases of infection by Leishmania have been reported on all the continents except Australia. In the Americas, Leishmania can be found from southern Mexico into the South American continent. The disease is widespread in the tropics. In the United States, cases have been reported in dogs, cats, and humans in Texas, Ohio, and Oklahoma.
The for leishmaniasis is quite and depends on the specific of infecting protozoan, as well as on the individual patient’s immune system response to infection. Cure rates are high with antimony compounds. There are no preventive vaccines. Preventing sandfly bites is the most immediate form of protection. Insect repellent, appropriate clothing, of windows, and fine mesh netting will reduce exposure.
Bibliography
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Lane, R. P. “Sandflies (Phlebotominae).” In Medical Insects and Arachnids, edited by Richard P. Lane and Roger W. Crosskey. New York: Chapman & Hall, 1993.
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