Outpatient visit due to influenza like illness in sentinel hospitals in Xicheng district of Beijing, 2009-2012

Abstract

Objective To understand the incidence of influenza like illness (ILI) and estimate the disease burden caused by ILI in Xi-cheng district of Beijing.Methods The data of the early warning system for infectious disease in medical institutions and the National Influenza Surveillance Network were used for the study.The surveillance data of ILI from 2009 to 2012 in two sentinel hospitals in Xicheng district were collected.Excel 2007 and SPSS 13.0 were used to analyzed the statistical data.Results A total of 72 414 ILI cases were reported by two sentinel hospitals from June 2009 to May 2012,the average proportion of ILI cases in outpatients was 1.85％.During the period of 2009-2010 influenza season,average proportion of ILI in outpatients was 2.38％,the RT-PCR positive rate of influenza virus nucleic acid detection was 39.70％,the estimated influenza infection rate was 38.63％ and the influenza cases accounted for 9.19‰ of the outpatient visit in sentinel hospitals.During 2010-2011 influenza season,the average proportion of ILl in outpatients was 2.02％,the RT-PCR positive rate of influenza virus nucleic acid detection was 18.68％,the estimated influenza infection rate was 15.33％ and the influenza cases accounted for 3.10‰ of the outpatient visit in two sentinel hospitals.During 2011-2010 influenza season,the average proportion of ILI in outpatients was 1.28％,the RT-PCR positive rate of influenza virus nucleic acid detection was 18.23％,the estimated influenza infection rate was 15.66％ and the influenza cases accounted for 2.00‰ of the outpatient visit in two sentinel hospitals.ILI visits focused on child outpatients and fever clinics under the age of 15 years old.The peak of RT-PCR positive detection curve and the peak of outpatient visit due to ILI were consistent during three influenza seasons,which mainly occurred in winter and spring.Conclusions Outpatient visit due to ILI mainly occurred during winter-spring in Xicheng district.It is important to arrange the monitoring departments reasonably and carry out ILI pathogen spectrum surveillance to reduce disease burden caused by ILI. Key words: Influenza-like illness ;  Surveillance;  Disease burden