Delayed peak of human infections and ongoing reassortment of H7N9 avian influenza virus in the newly affected western Chinese provinces during Wave Five

Jin Li; Chuming Chen; Jinli Wei; Huaxin Huang; Yun Peng; Yuhai Bi; Yingxia Liu; Yang Yang

doi:10.1016/j.ijid.2019.09.002

Delayed peak of human infections and ongoing reassortment of H7N9 avian influenza virus in the newly affected western Chinese provinces during Wave Five

Int J Infect Dis. 2019 Nov:88:80-87. doi: 10.1016/j.ijid.2019.09.002. Epub 2019 Sep 6.

Authors

Jin Li¹, Chuming Chen², Jinli Wei³, Huaxin Huang², Yun Peng², Yuhai Bi³, Yingxia Liu⁴, Yang Yang⁵

Affiliations

¹ School of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, China; Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China.
² Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China.
³ Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China; CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, China.
⁴ Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China; University of Chinese Academy of Sciences Medical School, Chinese Academy of Sciences, Beijing 101408, China. Electronic address: yingxialiu@hotmail.com.
⁵ Shenzhen Key Laboratory of Pathogen and Immunity, State Key Discipline of Infectious Disease, Shenzhen Third People's Hospital, Second Hospital Affiliated to Southern University of Science and Technology, Shenzhen 518112, China; CAS Key Laboratory of Pathogenic Microbiology and Immunology, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, Institute of Microbiology, Center for Influenza Research and Early-warning (CASCIRE), Chinese Academy of Sciences, Beijing 100101, China. Electronic address: yyszth2018@163.com.

PMID: 31499209
DOI: 10.1016/j.ijid.2019.09.002

Abstract

Objectives: Eight additional provinces in western China reported human infections for the first time during the fifth wave of human H7N9 infections. The aim of this study was to analyze the epidemiological and virological characteristics of this outbreak.

Methods: The epidemiological data of H7N9 cases from the newly affected western Chinese provinces were collected and analyzed. Full-length genome sequences of H7N9 virus were downloaded from the GenBank and GISAID databases, and phylogenetic, genotyping, and genetic analyses were conducted.

Results: The peak of human infections in the newly affected western Chinese provinces was delayed by 4 months compared to the eastern Chinese provinces, and both low pathogenic (LP) and highly pathogenic (HP) H7N9-infected cases were found. The LP- and HP-H7N9 virus belonged to 10 different genotypes (including four new genotypes), of which G11 and G3 were the dominant genotypes, respectively. Almost all of these viruses originated from eastern and southern China and were most probably imported from neighboring provinces. Genetic characteristics of the circulating viruses were similar to those of the viruses from previously affected provinces during Wave Five.

Conclusions: A delayed peak of human infections was observed in the newly affected western Chinese provinces, and reassortment has been ongoing since the introduction of H7N9 viruses. This study highlights the importance of continued surveillance of the circulation and evolution of H7N9 virus in western China.

Keywords: Avian influenza virus (AIV); H7N9; Reassortment; Wave Five; Western dissemination.

MeSH terms

China / epidemiology
Disease Outbreaks
Genome, Viral
Genotype
Humans
Influenza A Virus, H7N9 Subtype / classification
Influenza A Virus, H7N9 Subtype / genetics
Influenza A Virus, H7N9 Subtype / isolation & purification*
Influenza, Human / epidemiology
Influenza, Human / virology*
Phylogeny