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Infection with a species of Leishmania resulting in a clinically ill-defined group of diseases traditionally divided into four major types: 1) visceral l. (kala azar); 2) Old World cutaneous l.; 3) New World cutaneous l.; 4) mucocutaneous l.. Each is clinically and geographically distinct and each has in recent years been subdivided further into clinical and epidemiological categories. Transmission is by various sandfly species of the genus Phlebotomus or Lutzomyia. See tropical diseases, under disease. SYN: leishmaniosis.
- American l., l. americana SYN: mucocutaneous l..
- anthroponotic cutaneous l. a form of Old World cutaneous l., usually with a prolonged incubation period and confined to urban areas. SYN: chronic cutaneous l., dry cutaneous l., urban cutaneous l..
- canine l. a mild infection of dogs, usually confined to the muzzle or ears, produced by human disease-causing species of Leishmania; dogs therefore are important reservoirs of human infection, such as with visceral l. in the Mediterranean region.
- cutaneous l. infection with promastigotes (leptomonads) of Leishmania tropica and of L. major inoculated into the skin by the bite of an infected sandfly, Phlebotomus (commonly P. papatasi); it is endemic in parts of Asia Minor, northern Africa, and India, and is known by innumerable names, including tropical sores, tropical ulcers, and other indications of locality ( e.g., Aleppo, Baghdad, Delhi, or Jericho boil; Aden ulcer; Biskra button); the ulcer begins as a papule that enlarges to a nodule and then breaks down into an ulcer. Leishmanial cells are seen within histiocytes in hematoxylin and eosin–stained tissue sections. Two distinctive clinical and epidemiological diseases are recognized: the more common and widespread zoonotic rural disease with a moist acute form, caused by L. major, with reservoir rodent hosts, and an urban, anthroponotic, dry, chronic form of l. caused by L. tropica, without a reservoir host, and now largely controlled. See zoonotic cutaneous l., anthroponotic cutaneous l.. SYN: Old World l..
- diffuse cutaneous l. l. caused by several New and Old World species and strains of Leishmania (L. mexicana amazonensis, L. m. pifanoi, possibly L. m. garnhami and L. m. venezuelensis; in Ethiopia, L. aethiopica, and unidentified leishmanial agents in Namibia and Tanzania). The condition is associated with a suppressed cell-mediated immune response, so that the nonulcerating, nonnecrotizing cutaneous lesions can spread widely over the body; great numbers of parasite-filled macrophages are found in the dermal lesions. Healing does not appear to occur unless an acquired cellular hypersensitivity can develop. SYN: anergic l., diffuse l., disseminated cutaneous l., l. tegumentaria diffusa, pseudolepromatous l..
- mucocutaneous l. a grave disease caused by Leishmania braziliensis braziliensis, endemic in southern Mexico and Central and South America, except for the equatorial region of Chile; the organism does not invade the viscera, and the disease is limited to the skin and mucous membranes, the lesions resembling the sores of cutaneous l. caused by L. mexicana or L. tropica; the chancrous sores heal after a time, but some months or years later, fungating and eroding forms of ulceration may appear on the tongue and buccal or nasal mucosa; many variants of the disease exist, marked by differences in distribution, vector, epidemiology, and pathology, which suggest that it may in fact be caused by a number of closely related etiologic agents. SEE ALSO: espundia. SYN: American l., l. americana, bubas, nasopharyngeal l., New World l..
- nasopharyngeal l. SYN: mucocutaneous l..
- New World l. SYN: mucocutaneous l..
- Old World l. SYN: cutaneous l..
- l. recidivans a partially healing leishmanial lesion caused by Leishmania tropica and characterized by an extreme form of cellular immune response, intense granuloma production, fibrinoid necrosis without caseation, and frequent development of satellite lesions that continue the production of granulomatous tissue without healing, sometimes over a period of many years; organisms are difficult to demonstrate but can be cultured. SYN: lupoid l..
- visceral l. 1. a chronic disease, occurring in India, China, Pakistan, the Mediterranean littoral, the Middle East, South and Central America, Asia, and Africa caused by Leishmania donovani and transmitted by the bite of an appropriate species of sandfly of the genus Phlebotomus or Lutzomyia; the organisms grow and multiply in macrophages, eventually causing them to burst and liberate amastigote parasites which then invade other macrophages; proliferation of macrophages in the bone marrow causes crowding out of erythroid and myeloid elements, resulting in leukopenia, and anemia, splenomegaly, and hepatomegaly which are characteristic, along with enlargement of lymph node s; fever, fatigue, malaise, and secondary infections also occur; different strains of L. donovani occur; L. infantum in Eurasia, L. chagasi in Latin America. 2. visceral l. caused by Leishmania tropica, cultured from bone marrow aspirates of some military patients following the Gulf War. SYN: Assam fever, black sickness, Burdwan fever, cachectic fever, Dumdum fever, kala azar, tropical splenomegaly.
- zoonotic cutaneous l. a form of cutaneous l. characterized by rural distribution of human cases near infected rodents, particularly communal ground squirrels; characterized by acute rapidly developing dermal lesions that become severely inflamed, with moist necrotizing sores or ulcers that heal in 2–8-months after a 2–4-month incubation period; among nonimmune immigrants, multiple lesions may develop, which heal more slowly and leave disabling or disfiguring scars. A strong delayed hypersensitivity and involvement of immune complexes play a role in necrosis, which is part of the healing process and of the strong specific immunity that follows. SYN: acute cutaneous l., rural cutaneous l., wet cutaneous l..
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leish·man·i·a·sis .lēsh-mə-'nī-ə-səs n, pl -a·ses -.sēz infection with or disease (as kala-azar or oriental sore) caused by leishmanias
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n.
a disease, common in the tropics and subtropics, caused by parasitic protozoans of the genus Leishmania, which are transmitted by the bite of sandflies. There are two principal forms of the disease: visceral leishmaniasis, in which the cells of various internal organs are affected (see kala-azar); and cutaneous leishmaniasis, which affects the tissues of the skin. Cutaneous leishmaniasis itself has several different forms, depending on the region in which it occurs and the species of Leishmania involved. In Asia it is common in the form of oriental sore. In America there are several forms of leishmaniasis (see chiclero's ulcer, espundia). Leishmaniasis is treated with drugs containing antimony.
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leish·ma·ni·a·sis (lēsh″mə-niґə-sis) a protozoal infection caused by Leishmania; the principal classification is into cutaneous, mucocutaneous, and visceral types.Medical dictionary. 2011.