Investigation and analysis of avian influenza virus positive events in poultry markets in Tongzhou district of Beijing from March to May 2021

  Objective  To understand the distribution characteristics of avian influenza virus in the outside environment of poultry markets in Tongzhou district, Beijing, so as to provide scientific basis for future epidemic management.

  Methods   Descriptiveepidemiological methods were used from March to May 2021 to carry out field epidemiological investigation based on avian influenza virus positive cases in poultry markets in Tongzhou district, and expanded sampling was carried out in wholesale and retail markets of the whole district.

  Results  In 2021, there were 3 positive cases of avian influenza virus in poultry markets in Tongzhou district, involving two farmers’ markets and one wholesale market. From March to May, 40 samples were collected from each of the two farmers' markets. 74 samples were positive (30.83%), including 18 H7N9 samples (7.50%) and 56 H9N2 samples (23.33%). In March and May, expanded sampling was carried out in wholesale and retail markets in the whole region. A total of 327 food and environmental samples were collected from 23 markets in March, of which 58 were positive (17.74%). A total of 468 food and environmental samples were collected from 29 markets in May, of which 147 were positive (31.41%). In the expanded surveillance, 75.00% of the townships in the district tested positive results in March, and all townships in the district tested positive results in May.

  Conclusion  H7N9 and H9N2 subtypes were mainly detected in this incident, and H5 subtypes were also detected in the subsequent expanded surveillance in the whole region. It is necessary to continue to strengthen the external environment monitoring of avian influenza, and promote the joint prevention and control mechanism among various departments and regions.