Occurrence, ecology and management of Fascioloides magna in Bavaria, southern Germany

Abstract

In 2015, red deer infected with American liver fluke were discovered in the Veldenstein Forest area for the first time. This was the first detection of the fluke in a wild deer population in Bavaria. The aim of the study was to determine the American liver fluke prevalence rates in red deer, roe deer and wild boar in the Veldenstein Forest, as well as factors influencing these rates. Since 2018, the livers of 83% of the red deer culled in the study area have been examined, as well as those of the occasional roe deer and wild boar. The livers are classified by adspection and dissection into four levels of infection. The age of the animals was estimated based on dentition and tooth cementum annuli in the first molar (M1). The livers of 520 red deer, 226 roe deer and 75 wild boar were dissected. All wild boar livers tested negative. 3% of roe deer and 36% of red deer livers were positive. The red deer population was reduced to lower the prevalence, beginning in 2018. In the following years, it fell significantly. Medium and high infection levels were initially detected in 61% of adult red deer. Since 2018, the median number of flukes per infected liver has decreased significantly from 17.51 flukes/liver to 10.0 flukes/liver. On driven hunts, significantly more diseased deer were found than during hunting from raised hides. Furthermore, there are close correlations between the age of the red deer, infections, and the distance from the Pegnitz floodplains. The American liver fluke leads to the extinction of roe deer locally and to a massive infection and decimation of the red deer. Without a drastic reduction in the number of infected deer populations, there is a risk of large‐scale infection of native deer species across Bavaria.