Human Influenza A(H7N9) Virus Infection Associated with Poultry Farm, Northeastern China

Fan, Ming; Huang, Biao; Wang, Ao; Deng, Liquan; Wu, Dingfeng; Lu, Xiaoyan; Zhao, Qian; Xu, Sen; Havers, Fiona; Wang, Yanhui; Wu, Jing; Yin, Yuan; Sun, Bingxin; Yao, Jianyi; Xiang, Nijuan

doi:10.3201/eid2011.140608

Cited by 18 publications

(22 citation statements)

References 13 publications

(6 reference statements)

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“…For example, one study among poultry workers in Shenzhen found 7.2%‐14.9% with HI titers ≥16013. Another in Guangzhou found 1.6% poultry workers with HI titers ≥40 14 , and a study in Zhejiang Province reported 6.3% poultry workers with HI titers ≥807. Although our study found a lower seropositive rate among poultry workers in Guangdong than prior studies conducted in this province12, 13, 14, our study showed a higher seroprevalence among poultry workers in Guangdong compared with the poultry workers from the other five provinces included in the study.…”

Section: Discussionmentioning

confidence: 99%

“…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%

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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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Section: Discussionmentioning

confidence: 99%

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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“…The identification of the case occurred first prompting an environmental investigation with specimen collection at both poultry farms and nearby suppliers. From this investigation, H7N9 positive poultry and environmental specimens were identified in a farm in a north province of the previously not impacted areas [19]. In addition, H7N9 cases were identified in Xinjiang Province, along the western border of China during the second wave and Hubei in central China during the third wave.…”

Section: Discussionmentioning

confidence: 99%

Comparison of the first three waves of avian influenza A(H7N9) virus circulation in the mainland of the People’s Republic of China

et al. 2016

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BackgroundH7N9 human cases were first detected in mainland China in March 2013. Circulation of this virus has continued each year shifting to typical winter months. We compared the clinical and epidemiologic characteristics for the first three waves of virus circulation.MethodsThe first wave was defined as reported cases with onset dates between March 31-September 30, 2013, the second wave was defined as October 1, 2013-September 30, 2014 and the third wave was defined as October 1, 2014-September 30, 2015. We used simple descriptive statistics to compare characteristics of the three distinct waves of virus circulation.ResultsIn mainland China, 134 cases, 306 cases and 219 cases were detected and reported in first three waves, respectively. The median age of cases was statistically significantly older in the first wave (61 years vs. 56 years, 56 years, p < 0.001) compared to the following two waves. Most reported cases were among men in all three waves. There was no statistically significant difference between case fatality proportions (33, 42 and 45%, respectively, p = 0.08). There were no significant statistical differences for time from illness onset to first seeking healthcare, hospitalization, lab confirmation, initiation antiviral treatment and death between the three waves. A similar percentage of cases in all waves reported exposure to poultry or live poultry markets (87%, 88%, 90%, respectively). There was no statistically significant difference in the occurrence of severe disease between the each of the first three waves of virus circulation. Twenty-one clusters were reported during these three waves (4, 11 and 6 clusters, respectively), of which, 14 were considered to be possible human-to-human transmission.ConclusionThough our case investigation for the first three waves found few differences between the epidemiologic and clinical characteristics, there is continued international concern about the pandemic potential of this virus. Since the virus continues to circulate, causes more severe disease, has the ability to mutate and become transmissible from human-to-human, and there is limited natural protection from infection in communities, it is critical that surveillance systems in China and elsewhere are alert to the influenza H7N9 virus.

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“…Many published studies have reported that most human infections with the novel H7N9 virus had an epidemiologic association with exposure to live-poultry markets [7][8][9][10] and poultry farms [11]. Our previous studies have indicated that the novel H7N9 viruses were prevalent in chickens, pigeons, and ducks from such live-poultry markets [2].…”

Section: Introductionmentioning

confidence: 96%

Evaluation and application of a one-step duplex real-time reverse transcription polymerase chain reaction assay for the rapid detection of influenza A (H7N9) virus from poultry samples

Bao

Shi

et al. 2015

Arch Virol

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In China, a novel reassortant influenza A (H7N9) virus, which has caused 435 cases of human infection, has recently emerged. Most cases of human infections with the H7N9 virus are known to be associated with a poultry farm and live-poultry markets. In this study, a one-step duplex real-time reverse transcription polymerase chain reaction (RRT-PCR) assay was developed for the simultaneous detection of the hemagglutinin (HA) and neuraminidase (NA) genes of the H7N9 virus for effective surveillance and early diagnosis of cases from clinical samples collected from live-poultry markets or poultry farms. The detection limit of this assay was as low as 0.1 EID50 of H7N9 viruses, which is similar to the detection limit of the real-time RT-PCR assay released by the Word Health Organization. The coefficients of variation (CVs) of both inter-assay and intra-assay reproducibility were less than 1.55 %, showing good reproducibility. No cross-reactivity was observed with RNA of other subtypes of influenza virus or other avian respiratory viruses. The assay can effectively detect H7N9 influenza virus RNA from multiple sources, including chickens, pigeons, ducks, humans, and the environment. Furthermore, the RRT-PCR assay was evaluated with more than 700 clinical samples collected from live-poultry markets and 120 experimentally infected chicken samples. Together, these results indicate that the duplex RRT-PCR assay is a specific, sensitive, and efficient diagnostic method for the epidemiological surveillance and diagnosis of H7N9 virus from different sources, particularly poultry samples.

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Human Influenza A(H7N9) Virus Infection Associated with Poultry Farm, Northeastern China

Cited by 18 publications

References 13 publications

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

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

Comparison of the first three waves of avian influenza A(H7N9) virus circulation in the mainland of the People’s Republic of China

Evaluation and application of a one-step duplex real-time reverse transcription polymerase chain reaction assay for the rapid detection of influenza A (H7N9) virus from poultry samples

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