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Int J Infect Dis. 2019 Sep 6. pii: S1201-9712(19)30363-7. doi: 10.1016/j.ijid.2019.09.002. [Epub ahead of print]

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

Author information

1
School of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen, 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.

Abstract

OBJECTIVES:

Eight additional provinces in western China reported human infections for the first time during the fifth wave of human H7N9 infections. Our study aimed 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. Meanwhile, full-length genome sequences of H7N9 virus were downloaded from 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 China, 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 4 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 possibly imported from neighboring provinces. Genetic characteristics of the circulating viruses were similar with the viruses from previously affected provinces during Wave Five.

CONCLUSION:

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. Our study highlights the importance of continued surveillance of the circulation and evolution of H7N9 virus in western China.

KEYWORDS:

H7N9; Reassortment; Wave Five; Western dissemination; avian influenza virus (AIV)

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