Surveillance of influenza a viruses in a live bird market, Yangon, Myanmar during 2017-2018

Abstract

Live bird markets play a significant role in highly pathogenic avian influenza (HPAI) virus spread and transmission. In Myanmar, the first HPAI-H5N1 outbreak was reported in 2006. Since 2014, routine influenza A virus surveillance in LBMs have been conducted in Myanmar by the Livestock Breeding and Veterinary Department in cooperation with FAO. However, there is limited information on virus characterization and evolution of influenza viruses in Myanmar. The objectives of this thesis were to detect influenza virus subtypes circulating in different poultry species from Mingalar-Taung-Nyunt live bird market (MTN-LBM) and to determine genetic characteristics and genetic diversity of influenza A viruses in the MTN-LBM. During December 2017 - December 2018, 455 swab samples were collected from broiler, layer, backyard chicken and ducks from the MTN-LBM. Screening of all 91 pooled samples for IAVs by real-time RT-PCR showed that 12 samples were positive for influenza A virus (M gene). In this study, 7 samples were identified as HPAI-H5N1. Among them, 4 IAVs were successfully isolated and characterized. Whole-genome sequence of 4 HPAI-H5N1 was revealed with highly pathogenic avian influenza characteristics. Phylogenetic analyses showed that the Myanmar HPAI-H5N1 viruses were clustered with HPAI-H5N1 clade 2.3.2.1c from China and Vietnam. In conclusion, this study suggests that MTN-LBM can contribute a significant risk of HPAI-H5N1 spread and transmission to poultry and human.