IgG抗体亲和力试验判定麻疹病例的价值

Contribution of measles virus IgG antibody avidity assay to the identification of measles cases

目的评价麻疹IgG抗体亲和力试验对判定麻疹病例的价值。方法以中国疾病预防控制信息系统2013-2015年天津市麻疹实验室确诊病例和麻疹排除病例为研究对象。回顾性追溯保存的病例血清,开展麻疹IgG抗体亲和力试验,重新对麻疹排除病例进行归类。结果共收集到326例麻疹病例血标本,其中实验室确诊病例267例,排除病例59例,≥20岁病例占92.33%(301/326)。麻疹IgG抗体亲和力试验显示,确诊病例和排除病例中麻疹IgG高亲和力抗体的比例分别为66.95%(158/236)和91.23%(52/57),差异有统计学意义(χ^(2=)13.33,P<0.001)。根据判定标准,15.25%(9/59)排除病例被重新判定为麻疹病例,其中8例是高亲和力抗体,有含麻疹成分疫苗(MCV)免疫史,判定为继发性免疫失败病例;1例为低亲和力抗体,有典型的麻疹临床症状,无MCV免疫史。结论麻疹IgG抗体亲和力试验能够提供有参考意义的血清学证据,可以减少麻疹急性期血清学诊断中由于IgM抗体假阴性而造成的错误排除。

Objective To evaluate the value of measles IgG antibody avidity assay in identifying the measles cases.Methods Data from the Measles Surveillance Information System was used to collect laboratory confirmed or discarded cases in 2013-2015,and then tracing back the blood specimens from all measles network laboratories in Tianjin.Measles antibody avidity assay was used to detect and to redefine cases from the discarded ones.Results A total of 326 measles cases including 267 laboratory-confirmed and 59 discarded cases were enrolled into this study,with 92.33%(301/326)of them aged≥20 years.Result from the measles IgG antibody avidity assay showed that the ratio of high-avidity was 91.23%(52/57)of the discarded cases,which was significantly higher than 66.95%(158/236)of the laboratory confirmed cases(χ^(2)=13.33,P<0.001).According to the case criterion,15.25%(9/59)of the discarded cases were redefined as measles cases.Eight out of the nine cases were high-avidity with measles containing vaccine(MCV)vaccination history that named as SVF cases.One in nine cases with low-avidity was with typical clinical symptomatic measles but with no vaccination history of MCV.Conclusion Measles IgG antibody avidity assay could provide reference serological evidence to reduce the error from those discarded cases caused by false negative results on IgM antibody,when diagnosing the measles cases.