Leishmaniasis is a group of three conditions, each caused by a different species of a protozoan parasite of the genus Leishmania.
Leishmaniasis normally affects canines and rodents and is transmitted, by bites, to humans by sandflies of the genus Phlebotomus in regions where the disease is endemic. The parasites live and multiply inside certain tissue cells, called macrophages, in infected animals or humans. When multiplication causes these cells to burst, the released parasites invade fresh cells. Sandflies become infected when they feed on the blood of infected individuals. Drug therapy and good nutrition are effective in treating the condition. A vaccine is being developed aimed at triggering an immune response in the body to early stages of the parasite's development.
Visceral
Leishmaniasis, or kala-azar, is caused by L. donovani and affects the spleen, liver, lymph nodes, intestines, bone marrow, and skin. The rate of fatality is nearly 90 percent in untreated cases but under 10 percent when treated.
Cutaneous leishmaniasis, or Oriental sore, is caused by L. tropica and is found in the Mediterranean area, the Near East, China, and parts of India. The infection normally remains fairly localized in the region where the sandfly bite occurredÑusually on the face, arms, and legs. Healing takes 2 to 18 months, leaving depressed, often
disfiguring, scars.
American leishmaniasis, or espundia, caused by L. braziliensis, occurs in southern Mexico and Central and South America but is most common in Brazil, Paraguay, and Peru. Characterized by disfiguring skin lesions that spread into the oral and nasal cavities, it may persist for years, if untreated, resulting in death from secondary infection.