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目的分析河北省甲型H1N1流感的流行病学特点及血凝素基因HA基因特征。方法通过中国流感监测信息系统收集河北省2011年4月至2017年3月流感及流感样病例(influenza-like illness,ILI)监测数据进行统计分析,选定期间分离的14株甲型H1N1流感毒株,对HA基因进行测序和比对分析。结果2011-2017年共检测ILI标本77 008份,甲型H1N1流感阳性2 699份,阳性率3.50%,全省11个地市均有该病毒检出,男女性别比为1.17∶1,各年龄组均可发病,检出率最高的是25~59岁组,期间共出现4次流行,近年来检出率高峰由冬季转为春季。14株甲型H1N1流感病毒的氨基酸同源性在96.9%~99.9%,分属不同的进化分支,变异氨基酸部分位于抗原决定簇,关键位点第222位未发生变化。2013年1月和12月份毒株持续变异是导致其流行的主要原因。2016、2017年的分离株与新疫苗株同源性较高(99.2%~99.5%)。结论河北省甲型H1N1流感流行具有明显的季节性,近年来感染以25~59岁年龄组为主。HA基因与其编码的氨基酸逐年变异,新疫苗株与目前流行甲型H1N1流感病毒高度同源。
Objective To analyze the epidemiological characteristics of influenza A (H1N1) and the HA gene of hemagglutinin gene in Hebei Province. Methods The surveillance data of influenza-like illness (ILI) from April 2011 to March 2017 in Hebei Province were collected and analyzed by China Influenza Surveillance Information System. The data of 14 strains of H1N1 influenza virus Strains, HA gene sequencing and alignment analysis. Results A total of 77 008 ILI specimens were detected in 2011-2017, 2699 were positive for Influenza A (H1N1), the positive rate was 3.50%. The virus was detected in 11 cities in the province with a sex ratio of 1.17: 1 The incidence rate was the highest in 25-59 years old group. Four epidemics occurred during the period. The peak detection rate was changed from winter to spring in recent years. The identities of the 14 strains of influenza A (H1N1) viruses varied from 96.9% to 99.9%, belonging to different evolutionary clades. The amino acid residues of the 14 strains were located in the antigenic determinants, and the 222th key locus did not change. The persistent variation of strains in January and December 2013 was the main reason leading to its popularity. The isolates of 2016 and 2017 had higher homology with the new vaccine (99.2% -99.5%). Conclusion The prevalence of influenza A (H1N1) in Hebei Province is obviously seasonal. In recent years, the infection mainly occurs in the age group of 25-59 years old. The HA gene and its encoded amino acid vary year by year, and the new vaccine strain is highly homologous to the currently circulating Influenza A (H1N1) virus.