Surveillance for avian influenza virus in poultry related environment in Guangdong, 2016−2020

  Objective  To investigate the distribution characteristics of avian influenza virus in poultry related sites in Guangdong province and provide evidence for the prevention and control of human infection with avian influenza virus.

  Methods  From 2016 to 2020, environmental samples were collected from 5 types of poultry related sites in 21 prefectures of Guangdong. The detection of influenza A virus was conducted by fluorescence quantitative PCR, and the positive samples were identified for subtype H5, H7 and H9 viruses. The epidemiological characteristics of avian influenza virus in environment of poultry related sites in Guangdong were described, and the results were analyzed by χ² test.

  Results  A total of 78013 poultry related environmental samples were collected in Guangdong from 2016 to 2020. In which 16303 were positive for avian influenza virus (20.90%), 2307 were positive for subtype H5 virus (2.96%), 1230 were positive for subtype H7 virus (1.58%) and 11285 were positive for subtype H9 virus (14.47%). Among the positive samples, mixed positive samples accounted for 9.82%. The positive rate of avian influenza virus in environment peaked in winter and spring, especially in 2019 and 2020, and the positive rate of subtype H7 virus peaked during 2016−2017, which was positively correlated with the number of human H7N9 virus infection cases (Spearman, R=0.828, P<0.01). Among all kinds of places and samples, the positive rates were high in poultry slaughter houses (29.75%), chopping block swabs (27.72%), and poultry cleaning swage samples (21.83%).

  Conclusion  Avian influenza virus contamination exists in all parts of Guangdong, and the incidence of the human infection with avian influenza virus is high in winter and spring every year. People engaged in poultry slaughtering and trade are at high risk for avian influenza virus infection. It is necessary to strengthen the surveillance for avian influenza virus in poultry related environment in winter and spring, strengthen environmental disinfection in all kinds of poultry related sites, and people with occupation exposure should pay attention to personal protection.