Parasitic Skin Infections.pdf - Dermatology 2019-2020 Dr Hussein A Al-Sultany Parasitic Skin Infections A parasite is an organism that depends on a

Parasitic Skin Infections.pdf - Dermatology 2019-2020 Dr...

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1 Dermatology Dr. Hussein A. Al-Sultany 2019-2020 Parasitic Skin Infections A parasite is an organism that depends on a living host, for one or more of its essential metabolic requirements. Cutaneous Leishmaniasis (Baghdad Boil) Cause: Leishmaniasis is caused by Leishmania , which is a dimorphic parasite (present as promastigote form in the gut of Phlebotomous sandfly, and in amastigote form in the macrophage of human). Life Cycle: Phlebotomous sandfly female ( vector ) ingests amastigotes while taking a blood meal from the skin of a human or other mammals ( reservoir ). Amastigotes transform into promastigotes in the vector’s gut, then the sandfly inject it into skin of a human ( host ). Promastigotes become amastigotes inside the host, and then taken by the macrophages within which they multiply. Clinical Types of Leishmaniasis: 1. Cutaneous Leishmaniasis (CL), including: old world CL and new world CL. 2. Mucocutanous Leishmaniasis. 3. Visceral Leishmaniasis (Kala-Azar). Old World Cutaneous Leishmaniasis: (Baghdad Boil, Delhi Boil , Little Sister). It is caused by: L. major , L. tropica , L. aethiopica, or L. infantum . Epidemiology: Old world include the Mediterranean basin, Southern Europe, Africa, and Asia. CL is an endemic disease in Iraq. Children are the commonest age group affected; since immunity is acquired from the initial infection. Clinical Features: Incubation period: is variable (average: 2-3 months). Onset: is insidious and usually at autumn or winter. The predilection sites: are the exposed parts especially face, lower limbs, and hands. The lesions: dusky red, indurated, painless and non-tender nodules, involving the exposed parts, with slow evolution (more than one month duration). ●Two variants are described: Wet (Ulcerative, Rural) type: caused by L. major . The IP less than 2 months. Healing within 2-6 months (rapid course). Residual scar larger and deeper that of dry type. Dry (Non ulcerative, Urban) type: caused by L. tropica . The IP is more than 2 month. Healing within 8-12 months (longer course). Residual scar smaller and more superficial. ●Leishmaniasis Recidivans (Chronic Leishmaniasis): Brown-red or brown-yellow papules, usually appear close to a scar of an old (mother)
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2 ●Post Kala-Azar Dermal Leishmaniasis (PKDL): Begins during the convalescence of visceral leishmaniasis, appearing on the face, forearms, and lower limbs, as discrete papules. ●Recurrent Leishmaniasis: Leishmaniasis usually gives lifelong immunity, but recurrent infection may occur in: (1) Immunesuppressed. (2) Elderlies. (3) Very early treatment. (4) Infection by a new strain. Diagnosis: A - History: more than one month history of painless skin nodules. B - Examination: dusky red, indurated nodules, on the exposed parts.
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