Fascioloides magna and other liver parasites in cloven-hoofed game from northeastern Bavaria, Germany: occurrence and pathological findings with special emphasis on red deer (Cervus elaphus)

Abstract

Abstract The first detection of Fascioloides (F.) magna in northeastern Bavaria in 2011 was presumably correlated to natural migration movements of free ranging wild ruminants originating from the neighboring Czech Republic, where high infection rates have been reported frequently. To gain more data on the continuing spreading and current occurrence of the giant liver fluke in surrounding regions, 700 livers of cloven-hoofed game originating from eleven different northeastern Bavarian counties were investigated for the presence of F. magna and accompanying liver parasites in the hunting season 2019–2020. Macroscopically altered liver tissue was further investigated by pathohistological and parasitological examination. F. magna was detected in 5.9% (38/640) of livers from red deer (0.7% < 1 year, 9.8% > 1 year; p < 0.05) whereas none of the investigated livers of wild boar, roe, and fallow deer was infected (n=60). Mild pathological alterations of the liver tissue were documented in 15, moderate in 14, and major in 9 of all F. magna-positive cases. Histologically, the fluke-specific pigment haematin, large trematode eggs, and periportal fibrosis were detected in the liver tissue of infected animals. In 9% of all investigated livers, parasitic stages of other parasites, i.e., Dicrocoelium dendriticum (6.0%), Fasciola hepatica (0.3%), Taenia spp. (1.7%), and Echinococcus multilocularis (1.0%), were found. According to the results of this study, F. magna is not restricted to formerly known affected regions of Upper Franconia, but is also present in the military training ground Grafenwöhr, Upper Palatinate, and the Bavarian Forest National Park, Lower Bavaria, with estimated prevalences of 3.6 and 16.4%, respectively, and thus seems to spread in suitable habitats in northeastern Bavaria.