Parasitology DepartmentMedical Faculty of USUParasitic dermatitis can be caused by filaria, schistosoma, LeishmaniaCausative agent: Onchocerca volvulusInsect vector: Black flies, Simulium sp.Distribution: Tropical Africa, Central America, spread to Arabian Peninsula.The damage caused to the skin b microfilariaeThis probabl due to immune andpossibl directl irritative mechanisme.!istopatholog consist of light infiltration "ith inflammation "ith inflammator cells around the dermal vessels. These include lmphoctes, histioctes, plasma cells, and eosinophils but not neutrophils. #eactive form $%o"da&: single limb, hperpigmentation, pruritus $giant ulcer ' li(ardskin&, papules, lmpadenitis. )e" microfilariae*on+reactive form: %mmetric involvement of limb,trunkTropical Africa - .atin America*umerous microfilariaeDiagnosis TreatmentDiagnosis !istologic e/amination of skin snip %mear of aspirate from skin incision %lit+lamp e/amination %erological method PC# has role in monitoring chemotherap D0C is contarindicated Ivermectin is the drug of choice %ingle dose of 123ugm,kg 4icrofilaricidal, need to repeat doseIs due to avian %chistosome, Trichobilhar(ia ocellata. #e5uire intermediate host a snail for developing.!uman can be infected b cercarial penetration.0rthema of the invaded area "ith a prickling or nettling sensation and highl sensitive individuals b local or generali(ed urticaria.This smptoms "ill develop after 67 hours e/posure and ma last for 6 to 8 das.This reaction is intensified b repeated e/posure. The initial irritation characteristicall soon subsides, leaving a minute macule at each penetration, but is follo"ed shortl b intense itching o,t region "ith transformation or the macule into papules.The height of the reaction is usuall reached on 6nd - 8rd da, then graduall subsides, but smptoms are reactivated b rubbing of the involve areas.Treatment ControlTrimeprazine orally and local application of palliaties to reduce the itching and sedation !hen indicated"#posure to the fresh!ater type of the disease can be greatly reduced during the bathing season by use of copper sulfate or other suitable molluscicide along the shores of fresh!ater la$es or ponds in effectie concentrations%Is due to Leishmania tropica Its morphology is identical with L.donovaniThis parasites found in the skin at the endothelial cells of the capillaries of the infected area, nearby lymph nodes.Vectors are sandfy (Phlebotomus sp)&hen the promastigote stage of Leishmania is introduced into s$in, the parasites are engulfed by local !hite cells% 'n neutrophilic leucocytes phagocytosis is usually successful, but in macrophages, the parasites deelop to amastigote form, multiply%'n the early stages, the lesion is characterized by the proliferation of macrophages that contain numerous amastigoteThe oerlying epithelium sho!s acanthosis and hyper$eratosis, !hich are follo!ed by necrosis and ulceration%(s the lesion heals, the macrophages and organisms gradually diminish in number and the lymphocytes and plasma cells increaseThe incubation o )riental sore has been reported arying from a fe! days* + months%The clinical features, Papules and nodules Ulcers -elapsing LesionsSecondary infections !ith bacteria are common%iagnosis TreatmentThe diagnosis is usually made by the microscopic e!amination of material obtained by puncture of indurated edge of the sore and stain with giemsa.The drug of choice" #ntimony sodium gluconate (penta$alent) Pentostam and solustibosan. (in% &''mg imIn%ection (''mg #tabrine ()uinacrine hydrochloride)*e$amisole +,'mg-day