Antibody survey for occupational exposure population of avian influenza and surveillance of external environment in Yangzhou, 2012-2018

Abstract

Objective To understand the antibody levels of H5N1 avian influenza virus (AIV) among occupational exposure population and the contamination status of AIV in the external environment in Yangzhou city. Methods The serum samples were collected from occupational exposure population of H5N1 AIV in Yangzhou from 2012 to 2018. Antibody against H5N1 AIV was detected by hemagglutination inhibition test. External environmental samples were collected from live poultry markets and other sites. Nucleic acids of influenza A virus (Flu A), subtypes of H5, H7 and H9 were detected by real-time fluorescent PCR. Results All 964 serum samples from occupational exposure population were negative for antibody against H5N1 AIV. For 2 493 external environment samples, 209 samples were positive for Flu A with an overall positive rate of 8.38%. The constitutional ratios of positive results for H5, H7, H9 and mixed infections were 3.83%, 0.96%, 54.55% and 40.19%, respectively. There were statistically significant differences (P<0.05) among positive rates of different years, regions, surveillance sites, specimen types and months. Conclusions No antibody-positive sample of H5N1 AIV was found in occupational exposure population. Contamination of H5, H7 and H9 AIV distributed widely in the surveillance areas in Yangzhou. The high risk of AIV infection existed mainly in urban and rural live poultry markets and in winter-spring seasons. Key words: Avian influenza; Occupational exposure population; External environment; Surveillance