Study on Outbreaks of Influenza-like Illness in Yunnan,2009

Objective To understand the characteristics of influenza-like illness(ILI) outbreaks in Yunnan province and provide evidence for the development of scientific and effective control measures.Methods The data of ILI outbreaks in Yunnan in 2009 were collected and analyzed Results Totally 72 ILI outbreaks occurred in Yunnan,resulting in 7 628 ILI cases.The attack rate ranged from 1.79% to 49.45%.The disease occurred all the year round with peak in Autumn.Twenty six outbreaks occurred in Zhaotong,Sixty eight outbreaks occurred in schools.The influenza viruses were isolated from the cases in 37 out of 54 outbreaks,including influenza H3N2 virus(in 12 outbreaks),influenza B virus(in 11 outbreaks),2009 pandemic influenza A(H1N1) virus(in 9 outbreaks) and influenza A(H1N1) virus(in 5 outbreaks).The interval between the finding of the first case and the response and the duration of epidemic was positive correlated.(r=0.896,P0.05).Conclusion More ILI outbreaks occurred in Yunnan in 2009 than in 2008,and 94% of the outbreaks occurred in schools.It is necessary to strengthen the ILI outbreak surveillance and reporting in schools and improve the sample collection and laboratory detection.