Histopathologie pulmonaire d'un modèle mammifère et dermatite cercarienne humaine

Abstract

Objective – People which have been repeatly exposed to agents of cercarial dermatitis, presented sometimes alteration of the general status with pulmonary disorders or anaphylactic shock symptoms, from which the mechanics remain unknown. Methods – In order to elucidate them, a mammalian model gerbil Meriones unguiculatus has been used for exposure to ocellate furcocercariae, emitted by naturally infected Lymnaea peregra, native from Leman Lake. A duck exposure, to the same cercariae, aimed to obtain identifiable adult worms. The duck Cairina moschata developed Schistosomatidae worms close to Ornihobilharzia. The gerbil experienced five exposures to the cercariae during seven days. It has been sacrified after the last exposure and submitted to histological analysis. Results – The gerbil skin displayed evidences of dermatitis, scratching changes associated with lymphocytic vasculitis, devoid of schistosomula. Grossly, the lungs showed whitish granulations alongside the lung arteries, their collaterals and the bronchial tree. These nodules corresponded to lesions of lymphocytic vasculitis developed beneath alive or faintly damaged worms. The peripheral lung parenchyma presented macrophagic alveolitis. The lung invasion by avian bilharziae of Austrobilharzia and Trichobilharzia has been reported in several mammalian models. In this study, the worms found in the gerbil were close to Ornithobilharzia. The identified pulmonary lesions could have the same nature than those responsibles for respiratory distress in asthmatic children and lung disorders in ricefield workers having superimposed cercarial dermatitis. Comment – Immature avian bilharziae could be dangerous for Humans repeatly exposed to their cercariae.