Epidemiologic characteristics of influenza outbreaks in Guangdong Province from 2004 to 2007.

[Objective]To understand the epidemiologic characters of influenza outbreaks reported in Guangdong Province, to take proper action for prevention and control of influenza. [Methods] Data of epidemiologic and virus of influenza outbreaks reported in 21 cities of Guangdong Province were collected from 2004 to 2007. [Results] The surveillance data from 2004 to 2007 showed that the peak of influenza outbreaks reported in Guangdong Province was during March to June .Seventy percent influenza outbreaks were reported by only three city (including Guangzhou, Shenzhen, Foshan) which population were crowded and over-floating . Over 94% influenza outbreaks reported were occurred in schools and kindergartens. While among the outbreaks reported by schools and kindergartens, seventy-three percent were reported by elementary schools . Influenza A (H3N2) and Influenza B were the most frequently detected virus type Point Mutations occurred in the B type virus antigenic determinants resulted in the epidemic of Influenza B type (Victoria Like) in the Guangdong Province in March, 2006. The total reported outbreaks number was only 25 in 2007, which was the least during the recent years. [Conclusion] The peaks of influenza outbreaks reported in Guangdong are in spring and summer. Children in elementary school and kindergarten are the major infected groups, which suggest that influenza vaccination to this group should be an important method on prevention and control for influenza in Guangdong Province.