1. Division of Biomedical Food Research, National Institute of Health Sciences, Tokyo, Japan
2. Department of Infectious Diseases, Hokkaido Prefectural Institute of Public Health, Hokkaido, Japan
3. Department of Veterinary Public Health, Nihon University, Kanagawa, Japan
4. Division of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
5. Laboratory of Animal Hygiene, Kitasato University, Aomori, Japan