Method Sera samples were collected by random cluster sam pling method from the workers in the service industry from 2002 to 2003 for the detection of HBVM, ALT and pathogenic enterobacteria.

• 方法以整群抽样方式在2002、2003年抽取观察对象,收集相关资料和血清标本,进行丙氨酸转氨酶(ALT)、乙肝血清标志物(HBVM)和肠道致病菌的检测。