Analysis on the epidemiology and etiology data of influenza like illness cases in Shandong Province from 2009 to 2012

Objective To understand the epidemic rules,viral type and activity level of influenza in Shandong Province from 2009 to2012,to provide scientific information for supervision and early warning of influenza.Methods Influenza like illness data were filled in web based forms,and throat and nasal swabs were collected in monitoring.Influenza virus was isolated in MDCK cell line.And influenza virus type was identified with hemagglutination inhibition test.Results During the past four years,influenza like illness accounted for 2.25 % of the total outpatients(446 406 out of 19 877 694).The ILI% of each year was 3.16%,1.98%,2.11% and2.01%,respectively.Statistical analysis results showed there was a difference between ILI%(P0.05).74.0% of ILI cases was children younger than 5.In total,40 257 specimen had been detected,from which 8 960 specimen(22.42%) was tested positive.From 2009 to 2012,the positive rate was 48.67%,17.28%,8.90% and 14.04%,respectively(P0.05).Spearman correlation analysis,r=0.874(P0.05),showed ILI% and isolating rate of virus strain were positively correlative.Conclusion Influenza virus is more active in 2009.The preceding strain changes with some uncertain rules.The epidemic character of ILI and active trend of influenza virus are highly similar.