Angiostrongylus vasorum in wolves in Italy: prevalence and pathological findings

BACKGROUND: Angiostrongylus vasorum is a nematode residing in the heart and pulmonary vessels of dogs and wild carnivores. In Europe the red fox is its reservoir, while only three records from wolves have been published. Angiostrongylus vasorum has a worldwide distribution, and many pieces of evidence demonstrate that it is spreading from endemic areas to new ones. In Italy, A. vasorum was reported with increasing frequency in dogs and foxes in the last decades, and now it is considered endemic throughout the country. Angiostrongylus vasorum can be asymptomatic or cause respiratory and circulatory disorders, at times causing severe disseminated infections. METHODS: Between February 2012 and December 2016, 25 wolves found dead in central Italy were submitted to the Istituto Zooprofilattico del Lazio e della Toscana for post-mortem examination. Samples of lungs, heart, liver, spleen, kidneys, mediastinic lymph nodes and brain were collected from each animal for histological examination. When adult and larval nematodes were microscopically seen in lungs, the other organs were processed, and five histological sections for each organ were examined. To confirm parasite identification, lung samples were submitted to a PCR-sequencing protocol targeting the ITS2 region of A. vasorum. RESULTS: Seven wolves (28.0%) harboured nematode larvae in lung sections. In two of the positive wolves, adult nematodes were visible in pulmonary arteries, in four animals larvae were also detected in other organs. DNA sequencing reactions confirmed parasite identification as A. vasorum in all the cases. CONCLUSIONS: As a result of the high prevalence of A. vasorum reported in wolves in the present study, a focus of high circulation could be hypothesised in central Italy. Nevertheless, the similarly high prevalence in foxes originating from the same areas were reported in previous papers. Histopathological evidence highlights the pathogenic potential of A. vasorum in the wolf, especially in juvenile animals.