Setaria tundra, an emerging filarioid nematode in roe deer (Capreolus capreolus) in northeast Italy.

Coincidental with decades of warming (high temperature and humidity) in the sub-Arctic region of Europe, the mosquito-borne filarioid nematode Setaria tundra is now associated with emerging epidemic disease, resulting in morbidity and mortality for reindeer and moose. Similarly, roe deer is also target of this nematode, as documented in Denmark, Germany and Bulgary. In the early 2000s, S. tundra was first described in roe deer in Piedmont (north Italy). Aedes spp. mosquitoes seem to be the most competent vectors for S. tundra and little is known about its pathogenicity in roe deer. After a first report in 2013 of S. tundra in Friuli Venezia Giulia-FVG (northeast Italy) roe deers, during 2014-2016 an investigation was undertaken to evaluate the its presence in road-killed roe deer from the Gorizia province. Currently, parasitological dissections of 17 roe deer were performed. During the necropsy, nematode specimens (1 to 58 per host) were found in the abdominal cavity. Based on their morphology and biometrics, the nematodes recovered were identified as Setaria tundra and preserved in alcohol or cryopreserved for further analysis Moreover, pathological lesions were described, documented and damaged tissue samples were collected for histological evaluation. The prevalence of S. tundra in FVG roe deer population is 47.1%, mean intensity 11 (range 1-58) and mean abundance 5. The adult worms were located free in the abdominal cavity where tracks left by worm migration were also seen. Macroscopical lesions were polysierositis with thickening spleen and liver serosa with fibrinous deposition on surface of the abdominal organs. Whereas, histological lesions were diffuse serositis, granulomatous reactivity with Muller's giant cells and calcifications. In our study in FVG, this the first recognition of S. tundra and the alarming aspect has been that some road killed roe deers showed some significant pathological peritoneal changes.