Objective  To understand the distribution of avian influenza virus and assess the risk of human infection with avian influenza virus in Yunnan Province from 2016 to 2017 and provide evidence for the prevention and control of avian influenza.

  Methods  A total of 827 poultry related environment samples were collected from 139 surveillance sites in 16 prefectures (municipality) in Yunnan. Quantitative PCR was carried out to detect influenza A and subtype H5, H7 and H9. χ² test was used to analyze the test results. The influenza A positive samples were used for virus isolation and subtype identification.

  Results  In 827 samples, 221 were influenza A virus positive (26.27%), in which 5 were subtype H5 positive (0.60%), 182 were subtype H9 positive (22.00%), and 7 were positive for both H5 and H9 (0.85%), respectively. 27 were unspecified (3.26%). The differences in positive rate of influenza A virus among different areas were significant (χ²＝122.043, P＜0.001). Wenshan (70.0%), Baoshan (58.49%), Nujiang (47.83%) had high positive rate of influenza A virus. The subtypes of avian influenza virus isolated from chicken embryos were H5N1 (0.89%, 1/112), H5N2 (1.79%, 2/112), H5N6 (1.79%, 2/112) and H9N2 (95.53%, 107/112). The differences in influenza A virus positive rate among different surveillance sites were significant (χ²＝127.920, P＜0.001). The positive rate was highest in urban/rural live poultry markets, followed by that in live poultry wholesale markets. The differences in positive rate of influenza A virus among different samples were significant. (χ²＝51.689, P＜0.001). The positive rate was highest in sewage for cleaning poultry, followed by chopping board swabs.

  Conclusion  In the poultry related environment in Yunnan, the main subtype of avian influenza virus were H9, H5, and the mixed. It is necessary to take comprehensive prevention and control measures.