INFLUENZA SURVEILLANCE IN CHONGQING IN 2004

Objective:To explore the rule of influenza in ChongQing city,in order to provide scientific proof for the prevention of influenza.Methods:Data of outpatient visits for influenza-like illness(ILI)and outbreaks of influenza were collected through National Influenza Surveillance Network.The epidemiology and pathogen of ILI and outbreaks of influenza were analyzed.Results:The percentage of the number of ILI cases accounted for 13.50% of total outpatient,there were two apparent peaks in April and December.The toal rate of isolation was 19.22%.Three peaks distributed in May,December and March.Predominant strain was H3N2 type during April～August,B type during September～February and H3N2 in March.Most ILI cases were younger than 15 year-old,which accounted for 89.24%.32 outbreaks of influenza were reported,31 of that occurred in Primary and Middle schools,H3N2 was the main type.Conclusion:Two peaks of influenza in Spring and Autumn were shown in Chongqing,people younger than 15 year-old were vulnerable population,the change of the type of strain in pathogen surveillance around August need paying more attention to.