甲型肝炎病毒(HAV)由粪-口途径传播,在卫生条件差的国家感染很普遍,人群在幼龄时几乎均遭感染并获终身免疫,且极少呈临床肝炎。随着卫生条件的改善,被HAV感染的年龄推迟,许多人在儿时未经无症状感染而在青年或成年时罹患临床肝炎。在许多发达国家,人群甲型肝炎(HA)抗体分布率与年龄相关并呈下降趋势,伦敦医学生 Hepatitis A virus (HAV) is transmitted by the fecal-oral route and is commonly found in countries with poor sanitation. The population is almost always infected and lifelong immunized at childhood, with very little clinical hepatitis. As sanitation improves, the age attributed to HAV infection is postponed, and many people develop clinical hepatitis in their youth or adulthood without childhood infection asymptomatically. In many developed countries, the population distribution of hepatitis A (HA) antibody is age-related and declining trend. London medical students