浙江省一起由免疫接种空白导致的流动人口麻疹暴发

目的 为核实浙江省某村1名麻疹确诊患儿家长报告同村有多名发热、出疹病例,并调查暴发原因.方法 疑似病例定义为2010年6月1日至8月3日,该村及其所在街道和周围邻村居民中出现发热伴出疹症状者;确诊病例为疑似病例中血清麻疹IgM抗体阳性者.在全村范围开展逐户搜索,通过中国疾病预防控制信息系统搜索该村所在街道及相邻村的麻疹报告病例.对全村8月龄至14岁流动儿童开展回顾性队列研究.结果 该村共发现19例麻疹病例(17例确诊和2例疑似),均为流动人口,罹患率以1～2岁组为最高(13%).首发病例6月4日抵该村后发病,在非法私人诊所就医,但未向卫生部门报告疫情,卫生部门通过患儿家长报告识别暴发时,疫情已持续1个月.315名8月龄至14岁流动儿童中,麻疹疫苗接种率为81%.无麻疹疫苗接种史的61名流动儿童中,16名有明确病例接触史者发病风险(88%,14/16)高于45名无病例接触史者(4.4%,2/45)(Fisher精确概率法,RR=20,95%CI:5.7～94).结论 该村流动儿童麻疹疫苗接种率低,非法私人诊所不按规定对病例进行报告、隔离和医疗诊治,是导致此次疫情暴发的主要原因.

An outbreak of measles among unvaccinated migrant population in Zhejiang province, from June to August, 2010

Objective On July 6, 2010, the parents of a patient with confirmed measles reported several suspected measles patients with fever and rash in their village. An investigation was carried out to verify and understand the cause of the outbreak. Methods Several suspected cases had an onset of fever and rash in this and other neighboring villages during June 1 to August 3,2010. A confirmed case was a suspected case with measles-specific IgM identified in the serum. We conducted door-to-door visits and searched the Chinese Center for Disease Control and Prevention Information System to identify cases, also conducted a retrospective cohort study among migrant children aged 8 months-14 years to identify risk factors related to measles. Results We identified 19 measles cases (17 confirmed case, 2 suspected cases)in the village, and all of them were migrants. Children aged 1-2 years had the highest attack rate(13%). The primary case-patient had onset on the day she arrived in this village(June 4,2010). Caretakers from an unlicensed private clinic were providing service in the village but did not report the outbreak to the public health authority. The outbreak was identified only after receiving a report from the parents of one of the patients, by that time the outbreak had lasted for one month. The measles vaccine coverage rate was 81% among the 315 migrant children aged 8 months-14 years. Among the 61 unvaccinated children, those who reportedly being contacted a measles patient had a higher attack rate(14/16, 88%)than those who did not(2/45, 4.4%)(Relative risk=20, Fisher' s exact 95% confidence interval: 5.7-94). Conclusion The low measles vaccine coverage among migrant children and lack of measures taken on the incident, timely isolation diagnosis/reporting by the caretakers from the unlicensed private clinic etc. had contributed to this prolonged outbreak. Measures need to be taken to improve the immunization services for migrant populations and to enhance measles surveillance programs in the area.