1. Department of Chronic Communicable DiseaseCenter for Disease Control and Prevention of Jiangsu Province Nanjing Jiangsu Province PR China
2. Department of Epidemiology, School of Public HealthNanjing Medical University Nanjing Jiangsu Province PR China
3. School of Medicine, Division of Infectious Diseases and Geographic MedicineStanford University Stanford California
4. Center for Disease Control and Prevention of Danyang City Zhenjiang Jiangsu Province PR China