ORIGINAL ARTICLE Serological and Virological Surveillance of Avian Influenza A Virus H9N2 Subtype in Humans and Poultry in Shanghai,

• The study shows evidence of occupational exposure to poultry increases the risk of infection with low-pathogenicity avian influenza virus H9N2. • Avian H9N2 influenza virus was circulating for 3 years in poultry markets in Shanghai before the novel H7N9 emerged in 2013. • The long-term maintenance of avian influenza virus genes in live poultry markets represents a major risk for emergence in the occupational poultry-exposed population as well as in the general population. Keywords: Avian influenza virus; H9N2 subtype; occupational exposure; poultry; serology Correspondence