流行季节前后流行性乙型脑炎病毒中和抗体及隐性感染和显性感染比值分析

目的 通过对流行季节前后健康人群流行性乙型脑炎(简称乙脑)病毒中和抗体水平检测,分析影响人群抗体水平及隐性感染和显性感染比值(简称比值)的因素.方法 根据既往乙脑发病率选取发病高、低两个地区,在每个地区采取整群抽样；用微量中和试验进行乙脑病毒中和抗体检测.结果 在流行季节前乙脑发病高、低两个地区(安康、铜川)乙脑病毒中和抗体阳性率(几何平均滴度)分别为81.32％(1∶27.84)、24.07％(1∶3.04),流行季节后分别为82.78％(1∶36.82)、27.31％(1∶3.28).在乙脑高流行地区随着年龄的增长抗体水平呈现明显的增长趋势,但在低流行区无此趋势,经过一个流行季节两个地区人群抗体的阳性率均无明显升高,但在乙脑高流行区抗体滴度升高；抗体阳性率为98.20％的安康地区的人群中隐性感染和显性感染比值为115∶ 111,抗体阳性率为23.40％的铜川地区的人群比值为5∶ 944,随着抗体水平的提高比值迅速提高.结论 自然感染是影响人群乙脑抗体阳性率的重要因素,在乙脑高发地区是主要因素.人群抗体水平是影响隐性感染和显性感染比值的重要因素,比值随人群抗体水平增高而增高.

Analysis on Japanese B encephalitis virus neutralization antibody titer in health people before and after epidemic season and the ratio of inapparent infection and apparent infection

Objective To detect Japanese B encephalitis virus（JEV） neutralization antibody（NA） titer before and after epidemic season and analyze the influencing factor of JEV NA titer,and the ratio of inapparent infection and apparent infection（II/AI）.Methods Two regions with high and low JE incidence rate respectively were chosen,samples were selected by cluster sampling in each region.The NA of JEV were detected by micro neutralization test.Results Before and after JE epidemic season,the positive rate of JEV NA and geometric mean titer（GMT） was 81.32%（1∶27.84） and 82.78%（1∶36.82）in Ankang Prefecture where JE incidence rate was high,24.07%（1∶3.04） and 27.31%（1∶3.28） in Tongchuan Prefecture where JE incidence rate was low.There was the tendency that JEV NA titer increased with advancing age in the region of high JE incidence rate,but not in the region of low JE incidence rate.The positive rate of JEV NA did not increase in Ankang and Tongchuan after JE epidemic season,but the Ankang＇s GMT increased after JE epidemic season.The II/AI was 115 111 in the crowd whose positive rate of JEV NA was 98.20%.The II/AI was 5 944 in the crowd whose the positive rate of JEV NA was 23.40%.There was the tendency that the II/AI increased with advancing the positive rate of JEV NA.Conclusions JE natural infection was the important factor that affected the positive rate of JEV NA,and was the main factor in high JE disease rate regions.The positive rate of JEV NA was important factor that affected the II/AI.