Analysis on the pathogenic characteristics of influenza viruses in Gansu Province, 2013-2015

Objective To offer a scientific basis for the influenza prevention and control, we analysed the influenza (flu) characteristics of Gansu province during the year of 2013 to 2015. Methods We detected the samples of flu virus, which collected from the throat swabs of outpatients with influenza-like illness (ILI) in the 19 national influenza surveillance sentinel hospitals of the Gansu province, by fluorescence quantitative PCR technique, the positive specimens were used to isolate and identify the virus with the canine kidney cells (MDCK). Results After the influenza virus nucleic acid detections of 37 332 ILI throat swabs, we got 5 928 positive samples, and the positive rate was 15.88%. From the 14 th week of 2013 to the 13th week of 2016, the positive rates of the influenza virus nucleic acid were in turn as following: 14.52%, 12.36% and 20.15% respectively. According to age groups, the results showed that the lowest positive rate of 12.78% was from the babies below 5 years old, which was significantly lower than that of the other age groups. The highest positive rate of 24.75% was came from the group of 15-24 years old. 1 630 influenza virus was isolated from 6 285 specimens, the positive rate was 25.93%, which including 395 A(H1N1), 524 seasonal H3N2, 342 B Victorian virus and 367 B Yamagata virus. Conclusions The epidemic types of influenza virus in Gansu province perform in the rule of alternative spreading. So it is necessary to take active measures to prevent and control human infection with the influenza virus. Key words: Influenza virus; Crowd monitoring; Virus culture; Polymerase chain reaction