First molecular detection of Sarcocystis ovalis in the intestinal mucosa of a Japanese jungle crow (Corvus macrorhynchos) in Hokkaido, Japan

- Sarcocystis spp. are highly prevalent among wild sika deer (Cervus nippon yesoensis) in Hokkaido, Japan.
- One of these causative species was recently identified as S. ovalis.
- Prevalence of S. ovalis among corvid birds as candidate for definitive host was investigated in southern Hokkaido.
- One Corvus macrorhynchos harbored S. ovalis detected by molecular and histological analysis.
- The present case is the first report on a natural definitive host for Sarcocystis spp. prevalent among C. nippon yesoensis.

Although cysts of Sarcocystis spp. have been detected in domestic and wild animals throughout Japan, their natural definitive hosts have not been fully elucidated. Additionally, in Hokkaido, several Sarcocystis spp. are highly prevalent among wild sika deer (Cervus nippon yesoensis), one of which is S. ovalis. The life cycle of S. ovalis is maintained in corvid birds. To identify the definitive host for S. ovalis in Hokkaido, we investigated its prevalence among corvid birds (Corvus macrorhynchos and C. corone). A total of 42 crow carcasses were collected during August 2015-July 2016 in southern Hokkaido. Examination for coccidian sporocysts in rectal feces and intestinal mucosa, detection of Sarcocystis DNA (18S rRNA gene) from intestinal mucosa samples, and histological observation of intestinal tissue were conducted. No Sarcocystis sporocysts were detected in fecal and mucosal samples by flotation. DNA from intestinal mucosa was positive in one crow (C. macrorhynchos). Phylogenetic analysis demonstrated the isolate clustered with S. ovalis and was closely related to isolates obtained from sika deer in Hokkaido. Histologically, S. ovalis gamogenesis (gamonts or gametes) and oocyst production were observed in the villi of the crow positive for S. ovalis DNA. However, the crow was negative for other coccidian parasites, such as Eimeria, by fecal examination. Our results suggested that crows harbor S. ovalis in the intestine and may serve as a definitive host of S. ovalis in Hokkaido. To our knowledge, this is the first report on a natural definitive host for Sarcocystis spp. prevalent among sika deer in Japan.