甘肃省卫生行业科研计划项目GSWST 2012-06;国家科技重大专项传染病监测技术平台项目2012ZX10004-208 This work was supported by grants for the Medical Research Project in Gansu ProvinceGSWST2012-06;National Major Project of Communicable Disease Prevention and Control: Communicable Disease Surveillance Platform2012ZX10004-208