Surveillance for avian influenza virus in live poultry related environments in Wenzhou, 2011-2016

Objective To understand the classification, composition and distribution characteristics of avian influenza virus in live poultry related environments in Wenzhou, and provide evidence for avian influenza prevention and control. Methods The samples were collected from live poultry related environments for the detection of influenza A virus, including subtype H5, H7 and H9, with fluorescent quantitative RT-PCR, and the results were statistically analyzed. Results A total of 1 885 specimens were collected. The positive rates of A, H5, H7, H9 influenza viruses were 53.3%, 9.8%, 15.3% and 8.6% respectively. The positive rates of H7N9 virus and unknown subtypes were 11.6% and 24.1% in poultry related environments. The positive rate of avian influenza virus increased year by year since 2011 and reached the highest (66.0%) in 2014. The monthly detection peaks were mainly in January or February, the positive rates were 72.3% and 71.2%, respectively. The area specific positive rates varied, which was highest in Longwan (75.4%), followed by that in Ruian (64.3%) and Yongjia (61.0%).The year, month and area specific differences in positive rate were significant. For different sample collection sites, the positive rate in poultry farms (6.94%) was significantly lower than that in farm produce markets (61.7%) and live poultry markets (52.8%). Among different samples, the chopping board had the highest positive rate (65.4%), and followed by sewage (59.3%) and drinking water (29.6%). The sample collection site and sample specific differences in positive rate were significant. Conclusion The circulation of avian influenza was still serious in Wenzhou, especially in live poultry related environments. It is necessary to strengthen the surveillance for avian influenza virus.