In recent years, the wild deer population in Japan has grown exponentially, causing severe feeding damage to the agricultural and forestry industries. Therefore, the game meat industry is being promoted for effective utilization of hunted animals. Wild animals are not hygienically controlled and can serve as reservoirs for pathogenic microorganisms. However, epidemiological information on wild animals in Japan remains insufficient. Recently, food poisoning-like cases have occurred because of raw venison infection with Sarcocystis spp. As the prevalence of Sarcocystis spp. in sika deer is very high in Japan and even fawns are infected, this study attempted to verify the vertical infection of Sarcocystis spp. in sika deer in Japan. Genetic detection of Sarcocystis 18S ribosomal RNA in fetal and maternal tissues from early to late gestation in sika deer revealed Sarcocystis Types 1-5 and Sarcocystis fayeri in the mother and fetus. Types 1, 2, 4, and 5 were detected in the maternal tissues of Ezo sika deer (Cervus nippon yesoensis) in Hokkaido, whereas Types 1 and 2 and S. fayeri were detected in fetuses. Types 1-5 were detected in Honshu sika deer (Cervus nippon centralis) in Mie Prefecture but not in the fetuses. Types 1, 2, and 4 were detected in the udder and milk samples. This indicates that Sarcocystis Types 1 and 2 and S. fayeri have the ability to pass through the placenta of sika deer and invade fetal tissues and Types 1, 2, and 4 may be transmitted orally via milk. These findings suggest that there is transplacental and transmammary transmission of Sarcocystis spp. in sika deer.
Keywords: Sarcocystis; epidemiology; food poisoning; game meat; sika deer; vertical transmission.