一起戊型肝炎暴发的血清流行病学调查

目的 了解一起戊型肝炎暴发的血清学特点。方法 对某单位在10d内先后发病的5例急性黄疸性肝炎患者、在该单位食堂就餐的1675人(暴发人群)及未就餐的邻近单位883人(对照人群)的血清在首发病例26d后进行抗-HEV IgM和IgG检测，数据进行统计学分析。结果 5例患者抗-HEV IgM和IgG均为阳性。暴发人群抗-HEV IgM和IgG的阳性率分别为8．7％和38．4％，而对照人群仅分别为0．1％和28．6％，差别均有非常显著意义。暴发人群145例抗-HEV IgM( )中，ALT增高32例，明显高于IgM(-)及对照；而抗-HEV IgM(-)的ALT增高比例并不高于对照人群。4例患者系列血清检测见抗-HEV IgM逐渐下降，感染后4个月多数转阴，而IgG在感染后第2～3个月达高峰，随后缓慢下降。暴发人群中抗-HEV IgM( )的IgG平均水平最高，IgM(-)而IgG( )的IgG平均水平亦明显高于对照，提示暴发人群中既往感染者受到了免疫加强。暴发人群中抗-HEV IgM( )者在性别及年龄组间差异无显著意义，但其中ALT增高男性的比例显著高于女性，而与年龄无关。结论 本次急性黄疸性肝炎的暴发由戊型肝炎病毒引起，与食源有关；抗-HEV IgM和IgG不仅可用于临床病例诊断，也可用于人群调查；感染危险性与年龄及性别无关，但男性ALT增高更常见。

Serological characteristics of a hepatitis E outbreak

Objective To look into the serological characteristics of a hepatitis E outbreak. Methods Sera from the first five patients with acute icteric hepatitis who developed the disease successively within ten days and the 1 675 employees routinely having their lunch in a dining hall of a department (outbreak population) were examined for anti-HEV IgM and IgG at 26th days after the outbreak, and the 883 employees of a neighboring department not having their lunch in the hall were selected as control (control population) . Results The five patients were all positive for anti-HEV IgM and IgG. The positive rates of anti-HEV IgM and IgG in outbreak population were 8.7% and 38.4% respectively, both significantly higher than those in control population which were only 0.1 % and 28.6% . The numbers with abnormal ALT in the 145 individuals with anti-HEV IgM(+) of outbreak population were significantly higher than those in the IgM(-) individuals of the same group as well as in control, while the abnormal ALT ratio in the IgM(-) individuals of the outbreak was not higher than that in control. The results from the four patients' serial sera showed that the anti-HEV IgM titers declined gradually and were undetectable at about 4th month after infection, and the IgG titers increased to peak in about 2-3 months after infection, then declined very slowly. The mean IgG titer of the anti-HEV IgM( + ) individuals was significantly higher than that of the IgM(-) but IgG( + ) individuals in outbreak population, and the latter was significantly higher than the IgG( + ) individuals in control, which suggested that the post-infection individuals' immunities to HEV were boosted during the outbreak. There was no difference between sex or age groups for the anti-HEV IgM ( + ) ratio, but the abnormal ALT was much more frequent in the anti-HEV IgM( + ) male than in the female, and no difference was observed between age groups. Conclusion The pathogen of the outbreak of acute icteric hepatitis was hepatitis E virus and associated with food intake. Anti-HEV IgM and IgG were used not only for diagnosis of hepatitis E but also for serveilence in mass population. The attacke risk was not associated with age or sex, but the abnormal ALT was much more frequent fresh infectors in male.