集中度和圆形分布法在高原地区青海省流感监测中的应用

Application of concentration ratio and circular distribution method in influenza surveillance in Qinghai province:2009-2018

目的分析高原地区青海省2009-2018年流感病毒活动的季节性特征,为高原地区科学防控流感提供依据。方法从中国流感监测信息系统中,以月为单位导出流感核酸检测阳性数据,采用描述流行病学方法、集中度、圆形分布法和相关性分析高原地区青海省2009-2018年流感病毒活动在时间上的特征。结果高原地区青海省2009-2018年流感病毒核酸检测共检出7788份阳性标本,其中2009、2014和2016-2018年流感病毒核酸阳性检出标本数均高于2010-2013年和2015年;2009-2018年集中度M值分别为0.92、0.85、0.59、0.49、0.85、0.89、0.38、0.90、0.90和0.89;圆形分布γ=0.6091,α=340.09°,S=57.06,Z=2889.15,P<0.05,即高原地区青海省流感发病高峰日为12月10日,流行高峰期为1月6日-10月14日;M值和γ值呈高度相关(Pearson系数为0.905,P<0.001)。结论高原地区青海省2009、2014、2016-2018年流感病毒活动水平高于2010-2013年和2015年;前者流感病毒活动季节性在严格季节性和很强季节性两者之间波动,后者则在一定季节性、较强季节性和很强季节性范围内波动;流感病毒活动高峰日在当年11月中下旬、12月及和次年1月中上旬,高峰期在当年10月-次年3月。

Objective To analyze seasonal prevalence of influenza virus in Qinghai province and to provide evidences for prevention and control of influenza epidemic in the plateau region.Methods Monthly monitoring data on influenza virus nucleic acid detection in Qinghai,a province located on the Qinghai-Tibet Plateau,from 2009 through 2018 were derived from the Chinese Influenza Surveillance Information System.Epidemiologic description,concentration ratio,circular distribution,and correlation analysis were used to explore temporal distribution of influenza virus prevalence during the period in the region.Results Totally 7788 influenza virus nucleic acid positive specimens were detected in the region during the 10 years,with higher numbers of positive specimens in 2009,2014,and 2016-2018 than the number in other years.The M values of concentration ratio for the years from 2009 to 2018 were 0.92,0.85,0.59,0.49,0.85,0.89,0.38,0.90,0.90,and 0.89,respectively.The parameters of circular distribution of the positive specimens wereγ=0.6091,α=340.09°,S=57.06,and Z=2889.15(P<0.05),indicating that during a year the day with the highest influence virus prevalence is December 10 and the period with higher influence virus prevalence is from January 6 to October 14.The M value of concentration ratio was significantly correlated with the gamma value of circular distribution,with a Pearson coefficient of 0.905(P<0.001).Conclusion There were annual and seasonal fluctuations in the prevalence of influenza virus and the seasonal fluctuation varied yearly in Qinghai province during 2009-2018.