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leishmaniasis

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(lēsh″mă-nī′ă-sis) [Leishmania + -iasis] Any of a group of related chronic parasitic diseases of the skin, viscera, or mucous membranes, caused by species of the genus Leishmania. Leishmaniasis has occurred in epidemics but occurs mostly as an endemic disease in Asia, Africa, Latin America, and the Middle East; U.S. military personnel overseas may be infected. One type of leishmaniasis, kala azar, causes visceral infection and involves the mononuclear phagocytic system, causing inflammation and fibrosis of the spleen and liver. It can be fatal if untreated. Mucosal leishmaniasis infection produces mutilating lesions that destroy the mucosa, esp. in the oral cavity, larynx, anus, and vulva. In the two cutaneous forms of leishmaniasis, multiple skin ulcers form on exposed areas of the face, hands, arms, and legs. These are not painful or contagious but, if left untreated, can leave permanent, disfiguring scars. Leishmania organisms infect and reproduce inside macrophages and are controlled by T-cell–mediated response. The strength of the patient's immune system determines the severity of the disease. SEE: kala azar.

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PATIENT CARE: There is no vaccine against Leishmania. To prevent infection during exposure to sandfly vectors, topical repellants containing 30% to 35% N,N-diethyl-3-methylbenzamide (DEET) should be applied to the skin; and permethrin should be used to impregnate clothing, uniforms, bed netting, and screened enclosures. These measures also protect against infections caused by other biting insects, e.g., malaria.

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TREATMENT: Drugs used to treat leishmaniasis include amphotericin B, miltefosine, paromomycin, and sodium stibogluconate.

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American l. Mucocutaneous l.

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cutaneous l. An ulcerating, chronic, nodular skin lesion prevalent in Asia and the tropics and due to infection with Leishmania tropica. SYN: Aleppo boil; Baghdad boil; Delhi boil; Oriental sore; tropical sore.

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mucocutaneous l. A form of cutaneous leishmaniasis, involving principally the nasopharynx and mucocutaneous membranes, found in parts of Central and South America. The causative organism is Leishmania braziliensis usually transmitted by sandflies of the genus Lutzomyia. SYN: American l.

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tegumentary l. Leishmaniasis that involves the skin or mucous membranes.

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visceral l. Kala azar.

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lemniscus

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(lem-nis′kŭs, lem-nis′kī″, lem-nis′kē″) pl. lemnisci [L. lemniscus, pendent ribbon, fr. Gr. lēmniskos, a ribbon] An axon tract originating in secondary sensory nuclei and conducting signals toward the cortex via the thalamus.

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lateral l. An axon tract originating in the cochlear nuclei and ascending to synapse in the inferior colliculi; axons from the inferior colliculi ascend to synapse in the medial geniculate nucleus of the thalamus. This lemniscus is a middle link in the circuit carrying auditory information to the auditory cortex (Heschl's gyrus).

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medial l. An axon tract originating in the cuneate and gracile nuclei and ascending to the ventral posterior nucleus of the thalamus. This lemniscus is a middle link ...

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