云南省应对缅甸输入疫苗衍生脊髓灰质炎病毒病例实验室监测作用分析

目的分析云南省临沧市1例缅甸输入疫苗衍生脊髓灰质炎（脊灰）病毒（vaccine-derived poliovirus,VDPV）病例调查中实验室的监测情况,为云南省应对缅甸输入VDPV提供实验室依据。方法对与缅甸接壤地区入境就诊的急性弛缓性麻痹（AFP）病例标本进行脊灰病毒（PV）特异性引物逆转录-聚合酶链反应（RT-PCR）快速检测,现场采集病例密切接触者及边境地区健康儿童粪便标本开展脊灰病毒监测和肠道病毒型别特征分析;在病例所到过的临翔区和与缅甸接壤的镇康县连续6个月采集环境污水标本开展PV检测分析;采集境内外健康儿童血标本开展脊灰中和抗体水平分析,对输入风险进行评估。结果经实验室分析证实在中国消灭和维持无脊灰工作进程中监测到首例缅甸输入VDPV病例,病毒型别为Ⅰ型VDPV,有21个核苷酸变异,变异率2.3%。在病例密切接触者、健康儿童及外环境中未检测到同类病毒。在健康儿童中检测到NPEV 13株,在环境标本中检测到NPEV 5株,PVⅢ1株,境内儿童脊灰中和抗体Ⅰ、Ⅱ、Ⅲ型阳性率分别是100.00%、100.00%、98.00%;境外儿童三型阳性率分别是94.34%、100.00%、84.91%。结论云南省脊灰监测系统敏感性高,具备及时发现输入疫情的能力,病例输入后开展人际监测和环境监测,证实边境地区有较好的免疫屏障,未在云南省境内引起二代病例,但云南省面临再次输入的风险较大,应充分发挥实验室监测作用,严防病例或病毒输入后引起本地传播流行。

Surveillance and epidemiologic analysis of a vaccine-derived poliovirus case imported from Myanmar to Yunnan province of China

Objective To survey and analyze the epidemiologic data collected from the first case of vaccine de- rived poliovirus （VDPV） imported from Myanmar to the border area of Yunnan province of China. Methods RT-PCR was used to quickly test the specimens of an acute flaccid paralysis （AFP） cases immigrated from Myanrnar bordering with China. Poliovirus and enteroviruses were monitored in stool specimens from people who live in the border areas of China where the Myanmar VDPV case once stayed and passed through during his traveling to the border hospital of China for treatment. Stool samples from healthy children were collected at area of China bordering to Myanmar. Poliovirus was also monitored continuously in sewage water samples from Lincang city and Zhenkang county of Yunnan province for six months after the VDPV case left China. Polio neutralizing antibody levels in health children from border areas of China and Myanmar were tested to evaluate the risk of new import again. Results Laboratory analysis indicated that the VDPV case imported from Myan- mar was the first ease in Yunnan since the polio was eradicated in China from 2000. The virus was polio type I and there were 21 nucleotide （2.3%） difference comparing to the poliovirus reference sequence of Chi- na. The same virus was not detectable among children who might have close contact with the imported case, healthy children and sewage water. Thirteen non-polioviruses were detected in healthy children, 5 in sewage water, and I polio type III in environment. Positive rates of neutralization antibodies against polio type I , type II and type III in Chinese children were 100.00%, 100.00% and 98.00%, respectively, and in Myanmar children 94.34%, 100.00% and 84.91%, respectively. Conclusions The polio laboratory in Yunnan province of China monitored the imported polio case immediately and effective monitoring measures were taken to identi- fy the virus. Immune harriers had been built up in border areas to prevent the disease transmission in the border areas between Myanmar and China.