1. Laboratory of Infectious Diseases, Kitasato Institute for Life Sciences & Graduate School of Infection Control Sciences, Kitasato University, Minato-ku, Tokyo, Japan
2. Research and Education Center for Prevention of Global Infectious Diseases of Animals, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan
3. Department of General Internal Medicine, Tokyo Saiseikai Central Hospital, Minato-ku, Tokyo, Japan