Distribution, prevalence, and intensity of Sarcocystis infections in sika deer (Cervus nippon) of free-ranging populations in Germany and Austria

Abstract

Sika deer (Cervus nippon), which are native to the Japanese islands and the adjacent mainland of eastern Asia, have been introduced into Europe and established free-ranging populations in several countries. Various Sarcocystis species have been identified recently from farmed "mainland sika" deer in Lithuania and native "Japanese sika" deer in Japan. To study the distribution, prevalence and intensity of Sarcocystis infection in free-ranging sika deer outside of their natural range heart and/or diaphragm samples of 311 animals from nine populations in Germany and Austria were examined by histology.Overall, sarcocysts were detected in either heart or diaphragm of 107/311 deer (34.4%) with prevalence ranging roughly from 5 to 50% among the populations. Considering the 263 animals with both heart and diaphragm available, prevalence varied significantly (p < 0.0001) among calves (20.2%), yearlings (40.3%), and adult deer (49.1%) but did not differ between male and female deer (48.3% vs. 43.7%; p = 0.6483). Occurrence of sarcocysts in heart vs. diaphragm indicated a marginal difference (27.8% vs. 20.9%; p = 0.0839). Intensity of infection in all but one heart positive and all diaphragm positive animals was low (< 10 sarcocysts per square centimeter muscle cut). While heart sarcocyst counts of yearlings and adult deer were higher than those of calves and were higher in male compared to female sika deer, diaphragm sarcocyst counts did not differ significantly between age groups and sexes. Sarcocystis infection was demonstrated at variable prevalence in sika deer in all populations but intensity is apparently low. Further studies are needed to identify the species of Sarcocystis infecting sika deer naturalized outside their natural range.

Keywords: Austria; Diaphragm; Germany; Heart; Sarcocystis; Sika deer.