Human Infection with an Avian H9N2 Influenza A Virus in Hong Kong in 2003

TLDR

Avian H9N2 influenza A virus has repeatedly infected humans in Asia since 1998, and its continued presence in southern China poultry markets heightens the risk of avian‑to‑human transmission. The study aimed to identify the source of the 2003 Hong Kong H9N2 infection by genetically and antigenically characterizing the human isolate and market-derived viruses. The authors performed genetic and antigenic characterization of the human isolate and H9N2 viruses collected from Hong Kong poultry markets between January and October 2003. The study confirmed that a 5‑year‑old Hong Kong child was infected with H9N2 virus A/Hong Kong/2108/03, which is of purely avian origin and closely related to poultry market strains.

Abstract

ABSTRACT Avian H9N2 influenza A virus has caused repeated human infections in Asia since 1998. Here we report that an H9N2 influenza virus infected a 5-year-old child in Hong Kong in 2003. To identify the possible source of the infection, the human isolate and other H9N2 influenza viruses isolated from Hong Kong poultry markets from January to October 2003 were genetically and antigenically characterized. The findings of this study show that the human H9N2 influenza virus, A/Hong Kong/2108/03, is of purely avian origin and is closely related to some viruses circulating in poultry in the markets of Hong Kong. The continued presence of H9N2 influenza viruses in poultry markets in southern China increases the likelihood of avian-to-human interspecies transmission.