Surveillance for avian influenza virus in external environment of live poultry markets and serological analysis in population with occupational exposure in Changsha, Hunan, 2018−2021

  Objective  To understand the distribution and contamination of avian influenza virus in the external environment of live poultry markets and analyze the serological test results of population with occupational exposure in Changsha, Hunan province, from 2018 to 2021, and provide evidence for the prevention and control of human infection with avian influenza virus and policy-making.

  Methods  From January 1, 2018 to December 31, 2021 in Changsha, the external environmental samples of live poultry markets were collected and detected for avian influenza virus nucleic acid by real-time reverse transcription polymerase chain reaction, and horse blood cell hemagglutination inhibition test (HI) was used to detect H5N6 and H7N9 antibodies in serum samples, and turkey blood cell was used to detect H9N2 antibodies in serum samples. Software SPSS 19.0 was used to analyze the data and compare the positive rates of different samples, at different areas and at different times.

  Results  From January 1, 2018 to December 31, 2021, a total of 813 external environmental samples of live poultry markets and 150 serum samples of people with occupational exposure to poultry were collected in Changsha. The average positive rate of avian influenza virus in the external environment of live poultry markets was 64.58% in Changsha from 2018 to 2021, the annual positive rate showed an increasing trend from 2019 to 2021, and 254 samples were positive for subtype H9, accounting for the highest proportion. Among the six different types of sample, the positive rate in cage surface swabs was highest (79.03%), and the positive rate in poultry throat swabs was lowest (10.00%). Among the districts and counties in Changsha, Yuelu had the highest positive rate of avian influenza virus (94.67%). In terms of time distribution, the average annual positive rate was highest in the fourth quarter (67.50%), and lowest in the third quarter (57.82%), the positive rate was lower in summer than in winter. From 2018 to 2021, one H9N2 antibody positive sample was detected in the serological test for the population with occupational exposure to poultry. There were significant differences in the positive rate of avian influenza virus among different types of samples and different areas (P<0.05).

  Conclusion  The main subtype of avian influenza virus was H9 in the external environment of live poultry market in Changsha during 2018−2021. Winter was the season with high detection rate, and there was H9N2 recessive infection in population with occupational exposure. Trading, transportation and personnel flow in live poultry markets were high-risk factors for the cross-species spread of avian influenza virus. Live poultry markets should be regarded as a key places for avian influenza prevention and control, and continuous surveillance for avian influenza virus should be carried out to prevent the spread of avian influenza virus in human.