成都市甲型H1N1流感流行强度的时空演化机制分析

Analysis of the evolution mechanism of intensity of influenza a (H1N1) epidemics in Chengdu

目的探析成都市甲型H1N1流感(简称H1N1)的时空传播机制。方法利用2009年成都市H1N1数据,采用时空扫描统计量和小世界网络分析探讨疫情流行强度的演化机制。结果热点时间多分布在9月中上旬。热点区数量由市中心向外呈现递减趋势,其中主城6区占据多数热点区。热点区单位大多数是学校,占单位总数的51.85%。成都市H1N1传播的小世界网络呈现以下特点:H1N1病例大致是从较偏远的外圈层流向一圈层(主城区);主城六区以入度(输入型病例)为主;三圈层、较远的二圈层均为出度(输出型病例);主城六区间的传播网络就是强连通网络,并且主城区之间输入输出病例数值均较大;主城六区和双流、温江是H1N1传播网络的核心,在H1N1的传播过程中处于核心地位。结论不同圈层的区县在H1N1传播风险程度上差异较大;主城区的传播风险程度最高;学校是聚集性疫情的高危险区;在传染病疫情到来时加强这些区域及高风险单位防控措施的强度;对控制整个成都传染病疫情有重要作用。

Objective To analyze the temporal-spatial transmission mechanism of influenza A （H1N1） in Chengdu. Methods The space-time permutation scan statistic and the small world network model were conducted by using the data of the H1N1 collected from Chengdu in 2009 to explore the evolution mechanism of epidemic intensity of the H1N1. Results Most of hot spots of the H1N1 occurred in the early and mid-September. The number of hot spots reduced gradually from the Chengdu center to the outer circle direction, of which the most were in the six districts, constituting the main city area. Units in the detection of hot spots are mostly schools, accounting for 51.85% of the total number; The small world network model of the spread of the H1 N1 had the following features： The flow of the H1 N1 cases flowed roughly from the more remote outer layer to the central area of the city; The input flows（ imported cases） mainly occurred at the six dis- tricts, constituting the central area of the city, where most imported cases were clustered into, while the output flows （ ex- port cases） appeared in the third circle sections of the city and the second circle sections far away from the central area of the city, where most exported cases were clustered;The spread-network of the H1N1 among the six districts located in the center was a strongly interconnected network, the mean of the imported and exported cases between which was relatively larger. The six districts, Wenjiang and Shuangliu played a central role in the process of the spread of the H1 N1, which were the core of the small world network. Conclusions The counties located in different circle sections of the city had a big difference in the transmission risk of the H1N1 ,in which main urban districts,as being the core of the small world network, were the highest;As for the aspects of the specific institutional unit, schools were at a higher risk of clusters of the H1N1 occurrence than other units; So it is of great significance for emphasis placed on prevention and control measures in these high risk areas at the time of the arrival of infectious diseases to control infectious disease outbreaks in Chengdu.