1. Department of Acute Infectious Diseases, Municipal Center of Disease Control and Prevention of Qingdao, Qingdao, China
2. Department of EpidemiologySecond Military Medical University, Shanghai, China
3. Centre of Disease Control and Prevention of Huangdao District, Qingdao, China
4. Institute of Epidemiology and Microbiology, Huadong Research Institute for Medicine and Biotechnics, Nanjing, China
5. Department of Tropical Infectious DiseasesSecond Military Medical University, Shanghai, China
6. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China