Histopathological characterization of induced Paederus dermatitis caused by Egyptian rove beetles (Paederus alfierii)

Outbreaks of Paederus dermatitis (PD) have been reported in Kafr El-Sheikh governorate when Rove Beetles (genus Paederus) are accidentally brushed or crushed on the skin, releasing haemolymph pederin. The aim of this study was to characterize the histopathological changes of induced (PD) caused by Egyptian Rove Beetles (Paederus alfierii). Haemolymph extracts (pederin) of one and three insects were applied on shaved skin of two groups of rats. Skin specimens were collected after 12 h, 3, 7, 14 and 30 days after the extract application and processed for histopathological examination. Gross changes were indicated by erythema, eruptions, marked epidermal necrosis and large bullae formation. Microscopically, there was initial eosinophilic infiltration followed by a rapid destruction of the epidermis associated with exudation. The exudate penetrated the injured area of the epidermis forcing the degenerated cells apart and forming spaces which coalesced to form a vesicle with severe infiltration of the inflammatory cells in the dermis. Vesicles then dried forming crusts followed by repair which took a longer time in case of higher concentration.ConclusionReviewing our literature, this is the first time in Egypt to study the histopathological change of (PD) associated with P. alfierii. The induced dermatitis in this study is relatively more severe compared to (PD) of other Rove Beetles occurring in other regions of the world. The degree of dermatitis was directly correlated with the concentration of the toxin. There was no systemic reaction of the topical application of pederin on skin.