甲型肝炎 (甲肝 )是由甲肝病毒 (ＨＡＶ)引起的急性、自限性疾病。甲肝发病率与社会经济发展水平密切相关。血清流行病学研究表明 ,在世界不同地区人群的甲肝抗体阳性率为 15 %～ 10 0 % ,估计每年约发生 15 0万临床病例。大多数成年人感染后有临床症状 ,而幼儿一般无临床症状 Hepatitis A (Hepatitis A) is an acute, self-limiting disease caused by Hepatitis A virus (HAV). The incidence of hepatitis A is closely related to the level of social and economic development. Serological epidemiological studies have shown that in different parts of the world population of hepatitis A antibody positive rate of 15% to 100%, an estimated annual occurrence of 150 million clinical cases. Most adults have clinical symptoms after infection, while young children generally have no clinical symptoms