Etiopathological aspects of Elaphostrongylus cervi and Varestrongylus sagittatus infections in red deer in Bulgaria

Abstract

One hundred and ten faecal samples and fve lungs of red deer (aged 2 to 8 years) coming from the State Hunting Enterprise Vitinya in Bulgaria (Balkan Mountain) were examined. A larvoscopic examination of the faeces and helminthological necropsies, pathoanatomical and histological examinations of the lungs were performed. The overall prevalence of protostrongylids was 70% (77/110), and the prevalence of Elaphostrongylus cervi and Varestrongylus sagittatus was 68% (75/110), and 27% (30/110), respectively. In 25% (28/110) of the faecal samples, mixed infection with V. sagittatus and E. cervi was found. Mixed protostrongylid infections with those two species were detected in lungs of all animals. The macroscopic lesions found in the lungs parasitized by those helminths were classifed as follows: gray, dark-red to black stained portions on the lungs surface varying in shape and size; brown-black nodes clearly differentiated from the surrounding tissue; small, hard subserous nodules. The most frequently observed microscopic abnormalities were desquamatous bronchitis, alveolitis associated with accumulations of alveolar macrophages and eosinophilic granulocytes, haemorrhages in the alveoli and the alveolar septa, development of parasitic granulomas in the interstitium as well as a peribronchial, perilobular, disseminated and intralobular hyperplasia of the lymphoid tissue. The macroscopic and microscopic alterations depended on the species of the parasites found in the infammatory areas. The infections with E. cervi were most often associated with the lesions on the lungs surface varying in color, shape and size and with the small, hard subserous nodules, and those with V. sagittatus - with the brown-black nodes clearly differentiated from the surrounding tissue.