2000-2006年北京地区婴幼儿乙型流感病毒感染的监测

目的 通过连续的监测,了解北京地区婴幼儿乙型流感的流行规律.方法 采集2000年11月-2006年6月间因急性呼吸道感染到门诊就诊和住院患儿的呼吸道标本10 770份,分别经传代狗肾细胞(MDCK细胞)进行病毒分离和(或)间接免疫荧光进行流感病毒的检测,分离阳性的病毒进一步用血凝抑制试验进行流感病毒株的型别鉴定.结果 从10 770份呼吸道标本中,检测到乙型流感病毒阳性标本384份(其中有376份分离出病毒),总阳性率为3.57%.2000年11月-2006年6月,每年有一个乙型流感病毒的流行峰,几乎都出现在流感流行季节的后期.除2003-2004年流行季节乙型流感病毒的最高阳性检出率为2.91%(2004年4月)外,其余各年份的最高阳性检出率都高于10.00%.2005-2006年流行季节乙型流感病毒的最高阳性检出率达到历年的最高峰(23.69%,2006年3月).每年的乙型流感病毒的流行高峰检出的病例都以门诊患儿为主.乙型流感病毒阳性的门诊患儿中,＞3岁的患儿占77.6%(264/340),乙型流感病毒阳性的住院患儿中,＜3岁的患儿占66.0%(29/44).乙型流感病毒与其他呼吸道病毒的合并感染少见.监测期间乙型流感病毒与甲3型流感病毒的阳性检出率相差不大,但2005年9月-2006年5月期间,乙型流感病毒的阳性检出率明显高于甲3型(23.9%对1.1%).2000-2002年流行季节北京地区婴幼儿中流行的乙型流感病毒为B/Yamagata/16/168系,2002-2003年流行季节B/Victoria/2/87系乙型病毒占优势,2003年以后的流行季节同时流行着以上两个系的乙型流感病毒,但以B/Yamagata/16/168系为主.2005-2006年流行季节B/victoria/2/87系乙型病毒占优势.结论 2000年11月-2006年6月每年2-5月份都有一次乙型流感病毒的流行(除2002-2003年流行季节为2002年12月),检测阳性的患儿以门诊患儿为主;目前北京地区B/Yamagata/16/168系和B/Victoria/2/87系乙型流感病毒同时流行.

Surveillance for influenza B virus infections in infants and young children in Beijing, China

Objective To characterize the prevalence of influenza B virus infection in infants and young children in Beijing.Methods MDCK cell cuhure,indirect fluorescence assay(IFA)and hemagglutination inhibition(HI)assay were used to isolate and identify type B influenza viruses from clinical samples collected from outpatients and inpatients who visited the Affiliated Children's Hospital because of acute respiratory infections from Nov.2000 to Jun.2006.Results Out of 10 770 clinical samples collected during this surveillance period,384(3.57%,384/10 770)were positive for influenza B viruses.Circulation of influenza B viruses was revealed in the later epidemic season of influenza viruses each year.The detection rate for influenza B virus was higher than 10% each year during the survey.except in the period from 2003-2004 which was 2.91%.The highest detecting rate was 23.69%of the specimens colleted in Mar.2006.During the period of this study,most of the influenza B virus were identified from children who visited the outpatient department of the Affiliated Children's Hospital.Among those outpatients who were positive for influenza B,77.6%(264/340)were older than 3 years of age,whereas the inpatients positive for influenza B,66.0%(29/44)were under 3 years of age.Coinfection of influenza B virus with other respiratory viruses was not common,only one of the influenza B virus positive specimen was found also positive for influenza A3.There was no significant difference in positive rate between influenza virus B and A3.A significantly higher positive rate of influenza B virus than that of influenza A3 virus was seen from Sep.2005 to May 2006(23.9% vs 1.1%).B/Yamagata/16/168 lineage viruses were dominant during 2000-2002,and B/Victoria/2/87 lineage viruses became dominant during 2002-2003.After 2003,co-circulation of Victoria and Yamagata lineages of influenza B viruses was identified with predominance of Yamagata lineage viruses,while Victoria lineage viruses predominated during the 2005-2006 epidemic season.Conclusion Influenza B viruses were identified from February to May in every influenza season during this surveillance period of 2000-2006.Most of the positive specimens were those collected from outpatient department.Victoria and Yamagata lineages of influenza B viruses co-circulated in Beijing,China in recent years.