Abstract: Objective To understand the distribution of avian influenza viruses in the environment of live poultry markets in Gansu Province from 2017 to 2018,so as to provide scientific basis for the prevention and control of avian influenza epidemic. Method Environmental samples,including swabs of the surface and feces,were collected from the cages in live poultry wholesale markets,urban and rural farmers' markets,poultry farms ( households) and poultry free-range households in 14 cities (prefectures) of Gansu Province,and undergone real-time fluorescence RT-PCR for detection of influenza A virus nucleic acid (FluA). The positive samples were further detected for H5,H7 and H9 subtypes of avian influenza virus nucleic acids. Results Totally,7 038 samples were collected from the external environment,in which 1 510 samples were identified positive for FluA,with a total positive rate being 21. 45%. The positive rate for subtype H5,H7 and H9 was 0. 06% ( 4 /7 038),1. 19%(84 / 7 038)and 20. 52%(1 444 / 7 038),respectively. Mixed H5 and H9,and H7 and H9 infection was respectively detected in 2 and 20 samples. The positive rate for FluA was different in diverse samples ( χ2 = 50. 232, P<0. 01). The highest positive rate(36. 04%) was found in swabs of the chopping boards for killing or treating the poultry,and the lowest(13. 27%) in the water samples for feeding the poultry. FluA detection rate was the highest in January 2018 (36. 64%),and the lowest in June 2017 (5. 60%). The detection rate of FluA was the highest in Dingxi City (63. 32%). Conclusion The environmental sites in Gansu Province from 2017 to 2018 was contaminated by avian influenza virus,with subtype H9 being dominant. Subtypes H7 and H5 as well as mixed infection were also detected in our samples,which suggests that strengthened active monitoring is necessary in following work.

Key words: Avian influenza virus, External environment, Live poultry market, Gansu Province