Hou Jinlin, Liu Zhihua, Gu Fan
1Department of Infectious Diseases and Hepatology Unit, Nanfang Hospital, Nanfang Medical University, Guangzhou, China.
Int J Med Sci. 2005;2(1):50-57. doi: 10.7150/ijms.2.50. Epub 2005 Jan 5.
Hepatitis B is one of the most common infectious diseases globally. It has been estimated that there are 350 million chronic hepatitis B virus (HBV) carriers worldwide. The prevalence of chronic HBV infection varies geographically, from high (>8%), intermediate (2-7%) to low (<2%) prevalence. HBeAg-negative chronic hepatitis B (e-CHB) and occult HBV infection are two special clinical entities, and the prevalence and clinical implications remain to be explored. The predominant routes of transmission vary according to the endemicity of the HBV infection. In areas with high HBV endemicity, perinatal transmission is the main route of transmission, whereas in areas with low HBV endemicity, sexual contact amongst high-risk adults is the predominant route. HBV has been classified into 7 genotypes, i.e. A to G, based on the divergence of entire genome sequence and HBV genotypes have distinct geographical distributions. Three main strategies have been approved to be effective in preventing HBV infection. They are behavior modification, passive immunoprophylaxis, and active immunization. The implement of mass HBV immunization program is recommended by the WHO since 1991, and has dramatically decreased the prevalence of HBV infection and HCC in many countries.
乙型肝炎是全球最常见的传染病之一。据估计，全球有3.5亿慢性乙型肝炎病毒（HBV）携带者。慢性HBV感染的流行率因地区而异，从高流行率（>8%）、中等流行率（2%-7%）到低流行率（<2%）。HBeAg阴性慢性乙型肝炎（e-CHB）和隐匿性HBV感染是两种特殊的临床类型，其流行率和临床意义仍有待探索。HBV的主要传播途径因HBV感染的流行情况而异。在HBV高流行地区，围产期传播是主要传播途径，而在HBV低流行地区，高危成年人之间的性接触是主要传播途径。根据全基因组序列的差异，HBV已被分为7种基因型，即A至G型，且HBV基因型具有不同的地理分布。已批准三种主要策略可有效预防HBV感染。它们是行为改变、被动免疫预防和主动免疫。自1991年以来，世界卫生组织建议实施大规模HBV免疫计划，这已在许多国家显著降低了HBV感染和肝癌的流行率。
