Dermanyssus gallinae (Acari: Dermanyssidae) a cause of recurrent papular urticaria diagnosed by light and electron microscopy

Abstract

Background: Papular urticaria is a prevalent disturbing condition manifested by chronic or recurring papules caused by a hypersensitivity response to the bites of mosquitoes, bedbugs, fleas, and other insects. D. gallinae was previously indicated as an etiological agent for papular urticaria and chronic itching by several researchers worldwide.Objective: To throw light on D. gallinae as a cause of papular urticaria in Upper Egypt discussing associating risk factors.Material and Methods: The present study evaluated patients attending the Dermatology Outpatient Clinic, Sohag University Hospitals, Egypt, and who were diagnosed as papular urticaria. Some patients with recurrent papular lesions gave history of exposure to domestic poultry or birds’ nests and insect bites. They were selected from 97 patients who complained of itching. They were advised to bring any insects suspected of biting them or that come in contact with their skin, which were then referred to the Parasitology Unit for identification by light (LM) and scanning electron microscopy (SEM).Results: The examined arthropods were identified as D. gallinae in thirty cases and human fleas in two cases. LM and SEM showed the remarkable identifying features of D. gallinae female. Contact with sources of infection (insects) either birds' nests or chicken husbandry was proved to be a risk factor for recurrent papular urticaria. Contact of the same family members to the same source of infection caused prevalence of arthropods borne recurrent papular urticaria among family members. Gender and residence were not associated risk factors.Conclusion: This is, to the best of our knowledge, the first repot of D. gallinae infestation in Egypt. Pruritic dermatitis caused by D. gallinae (associated with papules and vesicles) may sometimes be mistaken for scabies. Therefore, meticulous history recording, and environmental inspection are necessary to discover the etiology of recurrent papular urticaria.