Surveillance and analysis of avian influenza viruses in the external environment of poultry in Anqing City， Anhui Province

Objective To determine the prevalence of avian influenza viruses in the external environment of poultry in Anqing City， Anhui Province， and provide scientific evidence for prevention and control of animal-derived influenza in humans.

Methods A total of 28 farmers’ markets/farms in 10 counties （cities， districts） of Anqing City， Anhui Province， were selected as surveillance sites by simple random sampling strategy. Poultry faeces and other related samples were collected for 6 consecutive weeks. Real-time fluorescence quantitative PCR was used to examine the nucleic acids of influenza A virus. Subtypes H5， H7， and H9 of avian influenza virus were further tested in the positive samples.

Results A total of 426 specimens were collected， among which 113 tested positive with a positive rate of 26.53%. Among the positive specimens， 104 were determined to be subtype H9， accounting for 92.04%. It did not significantly differ in the positive rate between the main and non-main urban areas （χ²<0.01， P>0.05） or among the specimens collected in different weeks （χ²=7.57， P>0.05）. However， it significantly differed in the positive rate among the specimens collected in the third week and other weeks （χ²=6.89， P<0.05）. Furthermore， among the different sampling sites， farms had the highest positive rate of 46.67%. Among the specimens from different sources， the surface-coated specimens from poultry cages had the highest positive rate of 34.78%.

Conclusion Avian influenza viruses are prevalent in the external environment of poultry in Anqing City. It warrants strengthening the surveillance and risk assessment to reduce the virus transmission in the external environment and risk of human infection with animal-derived influenza.