First report of the giant liver fluke (Fascioloides magna) infection in farmed fallow deer (Dama dama) in Poland – pathomorphological changes and molecular identification

A 3-year-old female fallow deer was subjected to the necropsy and virological testing, due to a suspected infectious disease in the herd of farmed deer in the Southeastern region of Poland. The animal was found negative for the presence of BVDV, BoHV-1, BTV, and EHDV antibodies and BVDV antigen. The toxicological examination did not reveal any coccidiostats, mycotoxins, rodenticides, carbamate pesticides, and organophosphorus pesticides. The flukes found during postmortem examination were first characterised microscopically as Fascioloides magna and later their identity was confirmed by PCR and sequencing. The autopsy revealed lesions characteristic for F. magna infection, including different size cystic spaces in the liver, filled with brownish mucous fluid and flukes, and black pigment covering the surface of parietal and visceral peritoneum with the highest concentrations localised next to the liver. The changes observed in the liver tissue were typical of liver cirrhosis. The results demonstrated that in Poland, where the cervid farming is developing dynamically, the problem of fascioloidosis is present and may probably exert a significantly negative influence on the productivity of such farms if no antiparasitic treatment is performed.