Sudden emergence of human infections with H7N9 avian influenza A virus in Hubei province, central China

Jiafa Liu,Edward C Holmes,Xiao Yu,Xiaoman Wei,Yingying Du,Yi Song,Jie Cui,Di Liu,Linlin Liu,Weifeng Shi,Bin Fang,Junqiang Xu,Mingyue Chen,Xiang Li,Guojun Ye

doi:10.1038/s41598-018-20988-9

Abstract

There have been five waves of H7N9 avian influenza virus (AIV) infection in humans since its initial emergence in China in 2013, posing a significant threat to public health. Hubei province was free local transmission during the first four waves of H7N9 AIV. However, multiple cases of human H7N9 infection were reported in Hubei during January 2017. To understand the molecular epidemiology that underlies this sudden emergence, we collected samples from 14 human cases of H7N9 influenza virus from Hubei province, along with environmental samples from different locations in Hubei. Our analysis revealed that the newly emerged human H7N9 viruses were all from persons exposed to poultry and shared the same origin as the environmental sampled viruses in the Yangtze River lineage of H7N9. Notably, we also documented an earlier and distinct importation from Jiangsu province that may have established a local environmental reservoir. Our study highlights the need for continued surveillance of H7N9 in both human and avian populations in central China.

Highlights

There have been five waves of H7N9 avian influenza virus (AIV) infection in humans since its initial emergence in China in 2013, posing a significant threat to public health
Ten of the infected individuals were exposed to live poultry markets (LPMs) or poultry transported from LPMs, while the remaining four cases were confirmed to have been exposed to backyard poultry
The HA (Figs 1; S1) and NA phylogenies (Fig. S2) revealed that the Hubei strains, including viruses isolated from both humans and the environment, generally clustered together and with H7N9 viruses from Zhejiang, Jiangsu and Anhui provinces sampled during wave 5, indicating that these viruses originated from the Yangtze River lineage

Summary

Introduction

There have been five waves of H7N9 avian influenza virus (AIV) infection in humans since its initial emergence in China in 2013, posing a significant threat to public health. Multiple cases of human H7N9 infection were reported in Hubei during January 2017. Since the first human infection with H7N9 AIV was identified in March 20131, there have been five outbreak waves in China during 2013–2017. Human infection with highly pathogenic H7N9 AIV in Guangdong province, China, was reported during the fifth wave, with an insertion of multiple basic amino acids at the HA cleavage site associated with enhanced virulence[5,6,7]. Human, nor environmental infections with H7N9 AIVs were documented in the first four waves in Hubei province despite annual www.nature.com/scientificreports/. Occupation Farmer Construction worker Unknown Garageman Food vendor Garment factory worker Retiree Retiree Construction worker Farmer Poultry worker Retiree Farmer Poultry worker

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Conclusion