LONGITUDINAL SURVEY OF INFLUENZA A VIRUSES IN LIVE BIRD MARKETS IN BANGKOK

Abstract

Live bird markets (LBMs) are places housing multiple poultry species from different sources and suitable environment for transmission and genetic reassortment of Influenza A viruses (IAVs). Most of human cases with IAVs infection had been reported with the history of exposure with poultry in LBMs. In this study, longitudinal survey was conducted in 3 LBMs in Bangkok during May 2014 to April 2015 to determine the occurrence of IAVs and to identify the subtypes and characteristics of IAVs in LBMs in Bangkok. This study was composed of 3 phases including live bird markets selection and sample collection, virus isolation and identification and genetic characterization of the viruses. In this study, oropharyngeal and cloacal swabs were collected monthly from each selected LBM and tested for IAVs. The result showed that 18 out of 1,374 swab samples (1.31%) were positive for IAVs identification by real-time RT-PCR. Two subtypes of IAVs were identified from ducks in a LBM including H2N3 (n=13) and H2N8 (n=5). Phylogeneic and genetic analysis of the viruses suggested that H2N3 and H2N8 posed low pathogenic avian influenza (LPAI) characteristics and grouped into the Eurasian lineage. This result suggested that several subtypes of LPAI were circulating in LBMs in Bangkok, Thailand. In summary, continuous survey of IAVs in LBMs is very important to investigate transmission and evolution of IAVs. Proper sanitation in LBMs and hygiene of vendors or workers' hygiene can reduce risk of IAVs transmission in LBMs.