1. Department of Gastroenterology Graduate School of Medicine The University of Tokyo Tokyo Japan
2. Division for Health Service Promotion The University of Tokyo Tokyo Japan
3. Department of Infection Control and Prevention Graduate School of Medicine The University of Tokyo Tokyo Japan
4. Department of Infectious Diseases Graduate School of Medicine The University of Tokyo Tokyo Japan
5. Division of Infectious Diseases Advanced Clinical Research Center Institute of Medical Science The University of Tokyo Tokyo Japan
6. Division of Infection Control and Prevention Education Research Center The Tokyo Health Care University Tokyo Japan
7. Department of Gastroenterology Kanto Central Hospital Tokyo Japan