云南省一起成人麻疹暴发的调查分析和控制效果评价

Epidemiological investigation and control of a measles outbreak among adults in Yunnan province

目的分析云南省德钦县1起成人麻疹暴发的原因,评价防控措施的效果。方法对疑似麻疹患者进行个案调查,收集病例血清和咽拭子/尿液标本,开展血清学和病原学检测。在全县范围内开展发热和/或出疹病例的主动搜索,采用回顾性队列研究分析引起暴发的主要因素。在首例病例报告4天后开展20-40岁人群含麻疹成分疫苗(MCV)应急免疫,并评价免疫后麻疹抗体水平。结果在42例麻疹暴发病例中,来自毗邻地区就诊病例23例,德钦本地病例19例。89.47%的德钦本地病例为20-40岁成人。病例的9株麻疹病毒分离株经鉴定为H1a基因型。在搜索的发热和/或出疹病例中,有明确病例接触史者中麻疹发病比例(10.1%,16/158)高于无病例接触史者(0.3%,3/1 209),且75%(12/16)的有明确病例接触者为医院暴露。德钦县20-40岁人群累计应急接种MCV 10 596人,接种后人群麻疹IgG抗体阳性率为100%,几何平均滴度为1∶1 452.87,疫情得到有效控制。结论本起成人暴发主要为易感人群的累积和院内感染引起。尽早开展以应急接种为主的综合防控措施可以迅速控制疫情。

Objective To determine the reasons for a measles outbreak among adults in Deqin county of Yunnan province, and to evaluate control measures for the outbreak. Methods All suspected measles cases were investigated. We collected blood samples and throat swabs or urine samples from cases for se- rological and etiologic assessment. An active search for fever and/or rash cases was conducted in the county to identify risk factors for the outbreak with a retrospective cohort study design. Emergency vacci-nation with measles containing vaccine （MV） was implemented within 4 days of the first case report; measles antibody levels were evaluated after the emergency vaccination. Results A total of 42 measles cases were confirmed in the outbreak; 23 were from adjacent regions and 19 were local people. 89.47% of local cases were 20-40 year old adults., Nine measles virus strains isolated from cases were identified as Hla genotype. The proportion （ 10. 1% , 16/158） of measles cases among searched-for fever and/or rash cases having a history of contact with measles was higher than the proportion （0. 3% , 3/1 209） among those without a contact history; 75% （12/16） of cases with contact histories were exposed in hospitals 10 596 local people aged 20-40 years received MCV in the emergency immunization response; the positivity rate for measles IgG antibody was 100% and the average geometric mean titer （GMT） was 1：1 452. 87 after emergency immunization. The outbreak was controlled effectively. Conclusions This out- break in adults was mainly caused by the accumulation of susceptible population and nosocomial exposure to measles. Early responses that include emergency vaccination can rapidly control out- breaks.