1. Department of Infectious Diseases; Tokyo Metropolitan Komagome Hospital; Bunkyo-ku Tokyo 113-8677 Japan
2. Department of Pediatrics; Tokyo Metropolitan Komagome Hospital; Bunkyo-ku Tokyo 113-8677 Japan
3. Department of Infectious Diseases and Applied Immunology; Institute of Medical Science, The University of Tokyo; Minato-ku Tokyo 108-8639 Japan