Abstract:
Objective To examine epidemic situation and pathogenic characteristics of influenza in Liaoning province from 2010 to 2014 and to provide evidences for formulating preventive and control strategies.
Methods Chi-square test and time series moving average method were used to analyze weekly data on influenza-like illness(ILI) from the 21 influenza sentinel hospitals and pathogen surveillance results of subtypes identified with hemagglutination inhibition test after viral isolation for specimens from ILI with Madin-Darby canine kidney(MDCK) cells from 2010 to 2014.
Results During the 4-year period,the reported ILI cases accounted for 4.01% of all outpatient clinic visits(651241 out of 16 236264),with the yearly proportion of 3.79%,3.41%,4.59%,and 4.19%,respectively.The proportion of ILI in all outpatient clinic visits was significantly different among the months during a year(
P<0.05).The ILI cases reported were mainly the people under the age of 15 years and 50% of the cases were small children aged 0-5 years.During the period,the yearly positive rate of influenza virus isolation were 1.20%,6.38%,7.35%,and 7.15%,with the dominant strain of H3N2,B,H3N2,and H1N1,respectively.The influenza outbreaks mainly occurred in winter and spring and at schools and childcare facilities.
Conclusion The seasonal variation of influenza epidemic is obvious with a peak from December of a year to March of next year and the prevalent influenza strains are multiple with the alternations of dominant strains in Liaoning province from 2010 to 2014.