Study on the application of Space-time scan to detect clusters of influenza A (H1N1) 2009 in Beijing

Objective To examine the temporal and spatial distrbution of influenza A (H1N1) 2009 and to provide evidence for disease prevention and control.Methods SaTScan8.0 software was used to conduct space-time scan statistic,and influenza A (H1N1) 2009 clusters were showed by ArcGIS8.3 software.Results From September 4 to December 17,October 16 to October 22,October 16 to October 29,October 9 to November 5,the cluster was showed by Temporal scan statistic with different time period of 7 days,14 days,30 days,50％.Influenza A ( H1N1 ) 2009 had high incidence.According the Marco Polo Bridge in Fengtai district for the center,a radius of 4.59 kilometer area was considered as the most likely cluster.The incidence of influenza A ( H1N1 ) 2009 increased abnormally,and 1474 cases of influenza A( H1N1 ),expected cases is 681.43,RR =1.78,P ＜0.001 with statistical significance.The most likely cluster was identified with different time periods by space-time scan statistic.It located in the southwest of Beijing city in a radius of 15.50-22.65 kilometer area from the October 16 to November 5.Furthermore,Secondary clusters were found in the northeast of Beijing,in a radius of 38.30-67.31 kilometer area,from October 9 to October 22.Conclusions The distribution of Influenza A (H1N1) 2009 in Beijing is not random,there are significant clusters in time and space.Space-time scan statistic is fit to analyze the clusters of influenza A ( H1N1 ) 2009 in Beijing.Useful information can be provided for future disease prevention and control. Key words: influenza A ( H1N1); Space-Time Clustering; Spatial-temporal