Live-Animal Markets and Influenza A (H7N9) Virus Infection

Bao, Changjun; Cui, Lunbiao; Zhou, Minghao; Hong, Lei; Gao, George F.; Wang, Hua

doi:10.1056/nejmc1306100

Cited by 124 publications

(114 citation statements)

References 2 publications

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“…29 However, the total number of cases has been suspected to be much higher than those reported since mild infections frequently remain undiagnosed. Similar to seasonal human influenza, these viruses tends to infect the elderly rather than children and many patients did not have any recorded contact with birds.…”

Section: Avian Influenza H7n9 Outbreak In Chinamentioning

confidence: 73%

Global alert to avian influenza virus infection: From H5N1 to H7N9

Poovorawan

Pyungporn

Prachayangprecha

et al. 2013

Pathogens and Global Health

120

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Outbreak of a novel influenza virus is usually triggered by mutational change due to the process known as 'antigenic shift' or re-assortment process that allows animal-to-human or avian-to-human transmission. Birds are a natural reservoir for the influenza virus, and subtypes H5, H7, and H9 have all caused outbreaks of avian influenza in human populations. An especially notorious strain is the HPAI influenza virus H5N1, which has a mortality rate of approximately 60% and which has resulted in numerous hospitalizations, deaths, and significant economic loss. In March 2013, in Eastern China, there was an outbreak of the novel H7N9 influenza virus, which although less pathogenic in avian species, resulted in 131 confirmed cases and 36 deaths in humans over a two-month span. The rapid outbreak of this virus caused global concern but resulted in international cooperation to control the outbreak. Furthermore, cooperation led to valuable research-sharing including genome sequencing of the virus, the development of rapid and specific diagnosis, specimen sharing for future studies, and vaccine development. Although a H7N9 pandemic in the human population is possible due to its rapid transmissibility and extensive surveillance, the closure of the live-bird market will help mitigate the possibility of another H7N9 outbreak. In addition, further research into the source of the outbreak, pathogenicity of the virus, and the development of specific and sensitive detection assays will be essential for controlling and preparing for future H7N9 outbreaks.

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Section: Avian Influenza H7n9 Outbreak In Chinamentioning

confidence: 73%

Global alert to avian influenza virus infection: From H5N1 to H7N9

Poovorawan

Pyungporn

Prachayangprecha

et al. 2013

Pathogens and Global Health

120

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“…Moreover, our environmental surveillance data suggested that a higher ratio of H9N2 viruses had been detected in Guangdong LPM than in other regions of China (Table 1) (14). Since live poultry was the major source of H7N9 viruses (8,(15)(16)(17), the coexistence of H9N2 viruses in that susceptible population was likely to generate appropriate conditions for the emer- gence of novel reassortment variants (6). From this, we proposed that the A/Guangdong/1/2013 (H7N9) virus was most likely a product of the most recent reassortment between a novel H7N9 virus and the local H9N2 viruses.…”

Section: Discussionmentioning

confidence: 99%

Continuing Reassortment Leads to the Genetic Diversity of Influenza Virus H7N9 in Guangdong, China

Zeng

et al. 2014

J Virol

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On 30 March 2013, a novel avian influenza A H7N9 virus causing severe human respiratory infections was identified in China. Preliminary sequence analyses have shown that the virus is a reassortant of H7N9 and H9N2 avian influenza viruses. In this study, we conducted enhanced surveillance for H7N9 virus in Guangdong, China, from April to August 2013. We isolated two H7N9 viral strains from environmental samples associated with poultry markets and one from a clinical patient. Sequence analyses showed that the Guangdong H7N9 virus isolated from April to May shared high sequence similarity with other strains from eastern China. The A/Guangdong/1/2013 (H7N9) virus isolated from the Guangdong patient on 10 August 2013 was divergent from previously sequenced H7N9 viruses and more closely related to local circulating H9N2 viruses in the NS and NP genes. Phylogenetic analyses revealed that four internal genes of the A/Guangdong/1/2013 (H7N9) virus-the NS, NP, PB1, and PB2 genes-were in clusters different from those for H7N9 viruses identified previously in other provinces of China. The discovery presented here suggests that continuing reassortment led to the emergence of the A/Guangdong/1/2013 (H7N9) virus as a novel H7N9 virus in Guangdong, China, and that viral adaptation to avian and human hosts must be assessed. IMPORTANCEIn this study, we isolated and characterized the avian influenza A H7N9 virus in Guangdong, China, from April to August 2013. We show that the viruses isolated from Guangdong environmental samples and chickens from April to May 2013 were highly similar to other H7N9 strains found in eastern China. The H7N9 virus isolated from the clinical patient in Guangdong in August 2013 was divergent from previously identified H7N9 viruses, with the NS and NP genes originating from recent H9N2 viruses circulating in the province. This study provides direct evidence that continuing reassortment occurred and led to the emergence of a novel H7N9 influenza virus in Guangdong, China. These results also shed light on how the H7N9 virus evolved, which is critically important for future monitoring and tracing of viral transmission.

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“…The remaining 23 cases were all imported from mainland China and included 16 cases and three deaths reported in Hong Kong, four cases and one death reported in Taiwan, one case in Malaysia, and two cases in Canada. Most influenza A(H7N9) virus infections in humans have been associated with direct or indirect exposure to poultry, including visiting live poultry markets (LPMs)3, 4, 5 and farms6, 7.…”

Section: Introductionmentioning

confidence: 99%

Sero‐epidemiologic study of influenza A(H7N9) infection among exposed populations, China 2013‐2014

Xiang

Bai

Kang

et al. 2017

Influenza Resp Viruses

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BackgroundThe first human infections of novel avian influenza A(H7N9) virus were identified in China in March 2013. Sentinel surveillance systems and contact tracing may not identify mild and asymptomatic human infections of influenza A(H7N9) virus.ObjectivesWe assessed the seroprevalence of antibodies to influenza A(H7N9) virus in three populations during the early stages of the epidemic.Patients/MethodsFrom March 2013 to May 2014, we collected sera from the general population, poultry workers, and contacts of confirmed infections in nine Chinese provinces reporting human A(H7N9) infections and, for contacts, second sera 2‐3 weeks later. We screened for A(H7N9) antibodies by advanced hemagglutination inhibition (HI) assay and tested sera with HI titers ≥20 by modified microneutralization (MN) assay. MN titers ≥20 or fourfold increases in paired sera were considered seropositive.ResultsAmong general population sera (n=1480), none were seropositive. Among poultry worker sera (n=1866), 28 had HI titers ≥20; two (0.11%, 95% CI: 0.02‐0.44) were positive by MN. Among 61 healthcare and 117 non‐healthcare contacts’ sera, five had HI titers ≥20, and all were negative by MN. There was no seroconversion among 131 paired sera.ConclusionsThere was no evidence of widespread transmission of influenza A(H7N9) virus during March 2013 to May 2014, although A(H7N9) may have caused rare, previously unrecognized infections among poultry workers. Although the findings suggest that there were few undetected cases of influenza A(H7N9) early in the epidemic, it is important to continue monitoring transmission as virus and epidemic evolve.

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Live-Animal Markets and Influenza A (H7N9) Virus Infection

Cited by 124 publications

References 2 publications

Global alert to avian influenza virus infection: From H5N1 to H7N9

Global alert to avian influenza virus infection: From H5N1 to H7N9

Continuing Reassortment Leads to the Genetic Diversity of Influenza Virus H7N9 in Guangdong, China

Sero‐epidemiologic study of influenza A(H7N9) infection among exposed populations, China 2013‐2014

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