Surveillance of influenza in Kaifeng municipality in Henan province, 2010

Objective To analyze the surveillance Results of influenza in Kaifeng in 2010, understand the incidence trend of influenza and etiological characteristics of influenza, and provide evidence for the prevention and control of influenza. Methods The surveillance of influenza like illness (ILI) was conducted in sentinel hospital through collecting throat swabs from ILI cases, conducting real time RT PCR to detect viral nucleic acid within 24 hours of sample collecting in influenza network laboratory and completing virus isolation and identification. Results A total of 91 661 patients were surveyed in outpatient and emergency departments in sentinel hospital and 853 ILI cases were detected. The majority of the cases were aged above 25 years (35.99%), but the cases number in people aged60 years was lowest. From the first week (4-10 January) to the 18th week (3-9 May) in 2010, the cases mainly occurred in people aged15 and25 years, but from the 42 week (25-31 October), the cases mainly occurred in infants less than I year old. Totally 571 throat swabs were taken from ILI cases, and 18 strains of novel influenza A (H1N!) virus (3%), 57 strains of unspecified influenza A viruses (10%) and 9 strains of influenza B virus (2%) were detected. No seasonal H1 and N3 viruses were detected. No influenza and novel influenza A (H1N1) outbreaks occurred in the year. Conclusion The seasonality of influenza incidence was obvious with the peak in the 3rd week. The majority of ILI cases were aged above 25 years, and predominant strain was unspecified influenza A virus.