1. Department of Pediatrics, Nara Prefecture Seiwa Medical Center, Sango, Japan.
2. Department of Pediatrics, Nara Medical University, Kashihara, Japan.
3. Division of Infectious Diseases, The Hospital for Sick Children, Toronto, ON, Canada.
4. Center for Infectious Diseases, Nara Medical University, Kashihara, Japan.
5. Department of Obstetrics and Gynecology, Nara Medical University, Kashihara, Japan.