Analysis of the survey on epidemic status of the outbreak of influenza B in Jinan City

Objective The present study was conducted to analyze the epidemiological characteris- tics of the epidemic status of the six outbreaks of influenza B in Jinan City and evaluate the control measures against the epidemic status. Methods Descriptive epidemiologic methods were used to ana- lyze the six outbreaks, and the nasopharyngeal swabs were collected to conduct the influenza virus isolation and identification. Results 6 influenza outbreaks, with 498 cases in all, occurred in six pri- mary and high schools in rural areas during February and April 2006, and the average attack rate was 7.97%, especially higher among the students below 12 years old. The main clinical symptoms were fever, cough, rhinorrhea and headache, the course of diseases often lasted for 3￣5 days. 117 samples of the nasopharyngeal swabs were collected. 33 strains of influenza B viruses were isolated and identi- fied, and the positive rate was 28.21%. Conclusions 6 outbreaks of influenza- like disease were all influenza B. Strengthening the morning examination in schools and strict isolation of the source of in- fection are significant measures to timely discover, prevent and control influenza.