Seasonal Variation and Factors Affecting <i>Trypanosoma theileri</i> Infection in Wild Sika Deer (Ezo Sika Deer <i>Cervus nippon yesoensis</i>) in Eastern Hokkaido
Yujon Hong,
Keisuke Suganuma,
Yuma Ohari,
Mitsunori Kayano,
Kenji Nakazaki,
Shinya Fukumoto,
Shin-ichiro Kawazu,
Noboru Inoue
Affiliations
Yujon Hong
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Hokkaido, Japan
Keisuke Suganuma
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Hokkaido, Japan
Yuma Ohari
Division of Risk Analysis and Management, International Institute for Zoonosis Control, Hokkaido University, Kita 20 Jyo Nishi 10, Sapporo 001-0020, Hokkaido, Japan
Mitsunori Kayano
Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Hokkaido, Japan
Kenji Nakazaki
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Hokkaido, Japan
Shinya Fukumoto
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Hokkaido, Japan
Shin-ichiro Kawazu
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Hokkaido, Japan
Noboru Inoue
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Hokkaido, Japan
Trypanosoma (Megatrypanum) spp. are isolated from domestic and wild ruminants, including deer, worldwide. The prevalence of trypanosomes in mammals is influenced by a number of factors such as host age and vector abundance. However, the seasonal variation of and factors affecting trypanosome infection in the wild deer population remain elusive. In this study, we analyzed the seasonal variation in trypanosome prevalence and the factors that affect Trypanosoma theileri Laveran, 1902, infection in wild sika deer (Ezo sika deer) Cervus nippon yesoensis (Heude, 1884) in Eastern Hokkaido through a two-year survey. Seasonal variation in the prevalence of trypanosome infection in the deer population ranged from 0 to 41% as per hematocrit concentration and 17 to 89% as per PCR results. In general, the prevalence of T. theileri by PCR in 2020 was higher than that in 2019. Moreover, the prevalence was significantly higher in the aged population than among the younger population. These findings may explain why individual conditions and sampling season were associated with trypanosome prevalence. This is the first study to investigate the seasonal variation in and risk factors affecting trypanosome infection in wild deer.
