1. United Graduate School of Veterinary Science, Gifu University, 1–1 Yanagido, Gifu 501–1193, Japan
2. Department of Veterinary Parasitological Diseases, Gifu University, 1–1 Yanagido, Gifu 501–1193, Japan
3. National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080–8555, Japan