Reighardia sternae Infection and Associated Lesions in a Yellow-Legged Gull (Larus michahellis) in Italy

<i>Reighardia sternae</i> is a pentastomid parasitising the respiratory system of larids and skuas, the pathological significance of which is still poorly understood. In this study, pentastomes found in the interclavicular air sac of a deceased and necropsied yellow-legged gull (<i>Larus michahellis</i>) were identified by parasitological and molecular methods and associated gross and histopathological lesions were evaluated. After morphological evaluation and molecular characterisation, the species <i>R. sternae</i> was identified. This is the first report of <i>R. sternae</i> infecting <i>L. michahellis</i> in Italy. Gross pathology showed generalised aerosacculitis, parabronchial edema, and enlargement of the heart, liver, and spleen. The systemic lesions found at histopathological examination were indicative of chronic cardiocirculatory failure, which led to the death of the gull. Moreover, inflammation was present throughout the lungs and air sacs in the form of some granulomas and diffuse small nodular aggregates rich in lymphocytes. The remnants of a parasite were observed within a granulomatous lesion in the lung, suggesting a primary host response to the parasite. These latter findings may suggest that the migration of <i>R. sternae</i> was the cause of the pathological granulomatous pictures in the examined yellow-legged gull.