中国2002～2003年度流行性感冒监测分析

Influenza surveillance program in 2002-2003,in China

目的 阐明 2 0 0 2年 4月至 2 0 0 3年 6月国内流行性感冒 (流感 )流行特点和流感病毒优势株的特性。方法 流感病毒分离采用鸡胚和细胞分离 ;流感病毒亚型鉴定采用血球凝集抑制试验 ;对流行株的HA基因核酸测序 ,分析其亲缘关系和抗原变异性。结果 2 0 0 2年 4月至 2 0 0 3年 6月 ,全国 2 3个省 (市 )和自治区共采集流感样患者咽拭子标本共计 1613 5份 ,经鉴定流感病毒阳性 1113株 ,分离率 6.9%。在 1113株流感病毒中 ,A1型 66株、A3型 544株、B型流感病毒Yamagada 98株和Victoria 40 5株 ,分别占总分离数的 5.9%、48.9%、8.8%和 3 6.4%。优势流行株为H 3N 2和B型Victoria株。A3型流感病毒除主要分离于 2 0 0 2年 12月和 2 0 0 3年 1月外 ,在非流行高峰期也有一定数量的分离。而B型Victoria系流感病毒主要集中分离于冬季流行高峰期 ,其流行株核酸序列分析属B型Victoria系株。A3型毒株血凝素基因的HA1系统树分析表明 ,其与A Panama 2 0 0 7 99同源 ,且有某些变异存在。结论 虽然感染人群的流感毒株依然是A1、A3和B型交叉出现 ,但以A型(H3N2 )和B型Victoria为优势株。与历年不同 ,B型Victoria分离比例增加及分布广泛是 2 0 0 2～2 0 0 3年度的特点。A型 (H3N2 )流行株有变异迹象值得密切注意。

ObjectiveTo study the prevalence of infl uenza viruses from April 2002 to June 2003. MethodsSubtypes were identified by HI test, HA gene was amplified by RT-PCR and the nucleotide sequences of HA gene were analyzed. Results During the period of April 2002 to June 2003, a total number of 16 135 throat swab specimens were collected in 23 provinces, metropolitans and municipalities with 1 113 strains identified as influenza viruses positive, by the Chinese National Influenza Center. The rate of isolati on was 6.9 %. Of the 1 113 strains, 66 strains were influenza A-H1N1, 54 4 strains were influenza A-H3N2 viruses while 98 and 405 strains belonged to B/ Yamagata and B/Victoria viruses with the rates of isolation on each subtype were 5.9 %, 48.9 %, 8.8 % and 36.4 %, respectively. Majority of influenz a A (H3N2) viruses were isolated in the epidemic period of December 2002 and Jan uary 2003 as well as in the non-epidemic period. Different to influenza A-H3N2 , most of the B/Victoria viruses were isolated in winter. The HA1 gene of B type strains belonged to B/Victoria lineage. Sequence analysis indicated that there were variations in influenza type in this epidemic season. ConclusionsAlthough influenza A subtype H1N1 and H3N2 as well as B type viruses were co-circulating in our country, the influenza A (H3 N2) and B/Victoria isolates were found the predominant strains in the period of this study which were different from the previous years. The fact that the incre ase of proportion on B/Victoria and its widespread in many areas suggested there had been a change of epidemiological features caused by influenza viruses in Ch ina. It seemed important to pay more attention to the variation of HA gene in in fluenza A type (H3N2) strains.