Third Wave of Influenza A(H7N9) Virus from Poultry, Guangdong Province, China, 2014–2015

Shumin Xie1, Weixin Jia1, Yicun Lin, Kaixiang Xing, Xingxing Ren, Wenbao Qi, and Ming Liao

Author affiliations: South China Agricultural University, Guangzhou, China

Abstract

Fourteen influenza A(H7N9) viruses were isolated from poultry or the environment in live poultry markets in Guangdong Province, China during 2014−2015. Phylogenetic analysis showed that all viruses were descended from viruses of the second wave of influenza A(H7N9) virus infections during 2013. These viruses can be divided into 2 branches.

A new influenza A(H7/N9) virus was detected in China on February 19, 2013, and has caused worldwide concern (1). Since 2013, the outbreak of this virus in humans has occurred in 3 waves. The third wave began when 2 additional laboratory-confirmed cases of human infection with this virus were detected in Xinjiang Province, China, on September 2, 2014. This wave has continued with increasing numbers of human cases during 2015, including infections in Fujian, Hong Kong, Guizhou, Jiangsu, and Guangdong Provinces. The largest number of human cases has been reported in southern China; >50 infected patients were detected in Guangdong Province January and February (2).

The virus has been identified as a novel triple reassortant of avian influenza A(H7N3), A(H7N9), and A(H9N2) viruses and has low pathogenicity in poultry (3–5). Influenza A(H7N9) virus is now endemic to China, and its continuing reassortment in poultry makes it probable that humans will continue to be infected sporadically.

Because influenza A(H7N9) virus−contaminated live poultry markets (LPMs) are regarded as major sources of human infections with this virus (6–8), we implemented LPM sampling programs in Guangdong Province and analyzed the evolution of the virus during the third wave. In this study, we also collected samples from chicken farms and integrated epidemiologic and sequence data to infer the genetic diversity and evolution of influenza A(H7N9) viruses found in poultry in Guangdong Province, China.

Ms. Xie is a research assistant at South China Agricultural University, Guangzhou, China. Her research interest is the epidemiology of avian influenza.

Acknowledgments

The study was performed in the National and Regional Joint Engineering Laboratory for Medicament of Zoonosis Prevention and Control, the Key Laboratory of Zoonoses Control and Prevention of Guangdong, the Key Laboratory of Animal Vaccine Development (Ministry of Agriculture).

This study was supported by grants from Program for National Broiler Industry (CARS-42-G09), the Science and Technology Projects of Guangdong Province (2013B020202001, 20140224), and the Science and Technology Projects of Dongguan (2014108101041) .

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Figures

Technical Appendix

. Additional information on influenza A(H7N9) viruses and their internal genes, Guangdong Province, China, 2014−2015. 1.22 MB

Suggested citation for this article: Xie S, Jia W, Lin Y, Xing K, Ren X, Qi W, et al. Third wave of influenza A(H7N9) virus from poultry, Guangdong Province, China, 2014–2015. Emerg Infect Dis. 2015 Sep [date cited]. http://dx.doi.org/10.3201/eid2109.150635

DOI: 10.3201/eid2109.150635

1These authors contributed equally to this article.