一起学校百日咳暴发疫情调查及防控策略

Investigation and prevention strategy of pertussis outbreak in a school

目的:分析2018年重庆市璧山区某小学百日咳暴发疫情,探讨百日咳的防控策略。方法:对报告疑似百日咳暴发疫情进行流行病学调查和病例个案调查;采集鼻咽拭子和血清标本,分别采用实时荧光定量PCR和间接酶联免疫吸附测定(ELISA)试验检测百日咳鲍特菌(BP)特异基因片段和血清抗百日咳毒素IgG抗体(抗-PT IgG);综合分析暴发疫情特征。结果:调查该小学451例学生,共确诊百日咳病例42例,罹患率为9.31%,发病年龄为8~9岁,均接种过4剂百白破疫苗;PCR和ELISA检测阳性率分别为85.71%和57.14%,一致率为57.14%,两种方法判断一致性弱(kappa=0.045)。42例中,医疗机构诊断为百日咳综合征16例和百日咳临床诊断病例8例,其次急性支气管炎10例、百日咳确诊病例和流感各4例。结论:判定本次疫情为百日咳暴发疫情,病例均为小学生,疾病诊断不规范,现有的抗-PT IgG检测阈值可靠性差,无用于疫情应急处置的百白破疫苗。建议加强医务人员百日咳诊断能力的培训,建立适合中国的PCR检测和血清抗体检测判断标准,适时纳入百日咳诊断标准,研究青少年和成人的百白破疫苗免疫策略。

Objective: To analyze the epidemic situation of pertussis in a primary school in Bishan District of Chongqing in 2018, and to discuss the prevention and control strategies. Methods: Epidemiological investigation and case investigation of suspected pertussis outbreak were carried out. Nasopharyngeal swabs and serum samples were collected, and real-time fluorescence quantitative PCR and indirect ELISA were used to detect the specific gene fragment of Bordetella pertussis(BP) and serum anti-pertussis toxin IgG antibody(anti-PT IgG). Finally, the outbreak characteristics were comprehensively analyzed. Results: A total of 451 students in the primary school were investigated, 42 cases of pertussis were diagnosed, the attack rate was 9.31%, and the age of onset was 8-9 years old, all students had received 4 doses of pertussis vaccine. The positive rates of PCR and ELISA were 85.71% and 57.14% respectively, and the consistency rate was 57.14%, the consistency judged by the two methods was weak(kappa=0.045). Among the 42 cases, there were 16 cases of pertussis syndrome and 8 clinical cases of pertussis, followed by 10 cases of acute bronchitis, 4 cases of confirmed pertussis and 4 cases of influenza. Conclusion: It is determined that the epidemic is an outbreak of pertussis, the cases are all primary school students, and the disease diagnosis is not standard. The existing anti-PT IgG detection threshold is not reliable and cannot be used for emergency treatment of DPT vaccine. It is suggested to strengthen the training of medical staff in diagnosing ability of pertussis, establish criteria for PCR detection and serum antibody detection that suitable in China, incorporate the diagnostic criteria of pertussis, and investigate the immunization strategy of pertussis vaccine in adolescents and adults.