[Classification and special characteristics of parasitic skin infections]

Classification of cutaneous parasitic diseases is relevant to gain an overview, but complex, because parasites are heterogeneous, encompassing unicellular protozoa and multicellular helminths. For clinical use, the classification may take into account the following aspects: (a) the initially infected organ: the intestine in e.g. gnathostomiasis, amebisias, or the skin, subdivided into either infestation of superficial skin areas in scabies, pediculosis, tungiasis, or active (without help of a vector) penetration into the subepidermal space in cutaneous larva migrans and cercarial dermatitis, (b) transmission route: active penetration of the skin such as in cutaneous larva migrans, larva currens, or via blood- or lymphvessels after uptake from the intestines (gnathostomiasis, dracunculiasis) or via arthropods as vector (leishmaniasis [often skin-restricted infection with protozoa], Chagas disease, as example for systemic infection with protozoa, or onchocerciasis [river blindness] and lymphatic filariasis as examples for helminths cutaneously transmitted by vectors), (c) dissemination (remaining in the skin or systemic spread in other organs as with Strongyloides stercoralis, schistosoma [Bilharziosis]), (d) permanent (scabies, pediculosis, tungiasis) or temporary infestation (bedbugs, fleas). Classification and overview of the various parasitic skin infections helps to guide treatment planning of patients, to keep rare infections in mind (e.g., to consider infection with Entamoeba histolytica besides ecthyma or pyoderma gangrenosum in patients with progressive perianal ulcers), and to consider a potential infection with Strongyloides prior to immunosuppressive therapies in patients with respective history. As such, timely diagnosis and treatment of a patient with acute or chronic papular dermatitis from endemic areas in Africa can prevent river blindness.