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- Volume 19, Issue 25, 26/Jun/2014
Eurosurveillance - Volume 19, Issue 25, 26 June 2014
Volume 19, Issue 25, 2014
- Editorials
- Surveillance and outbreak reports
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Two clustered cases of confirmed influenza A(H5N1) virus infection, Cambodia, 2011
In February 2011, a mother and her child from Banteay Meanchey Province, Cambodia, were diagnosed, postmortem, with avian influenza A(H5N1) virus infection. A field investigation was conducted by teams from the Cambodian Ministry of Health, the World Health Organization and the Institut Pasteur in Cambodia. Nasopharyngeal, throat and serum specimens collected from 11 household or three neighbour contacts including two suspect cases tested negative by reverse transcriptase-polymerase chain reaction (RT-PCR) for A(H5N1). Follow-up sera from the 11 household contacts also tested negative for A(H5N1) antibodies. Twenty-six HCW who were exposed to the cases without taking adequate personal protective measures self-monitored and none developed symptoms within the two following weeks. An unknown number of passengers travelling with the cases on a minibus while they were symptomatic could not be traced but no clusters of severe respiratory illnesses were detected through the Cambodian surveillance systems in the two weeks after that. The likely cause of the fatal infection in the mother and the child was common-source exposure in Preah Sdach District, Prey Veng Province. Human-to-human transmission of A(H5N1) virus was unlikely but genetic susceptibility is suspected. Clusters of A(H5N1) virus infection should be systematically investigated to rule out any human-to-human transmission. .
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Transmission of avian influenza A(H7N9) virus from father to child: a report of limited person-to-person transmission, Guangzhou, China, January 2014
We investigated a possible person-to-person transmission within a family cluster of two confirmed influenza A(H7N9) patients in Guangzhou, China. The index case, a man in his late twenties, worked in a wet market that was confirmed to be contaminated by the influenza A(H7N9) virus. He developed a consistent fever and severe pneumonia after 4 January 2014. In contrast, the second case, his five-year-old child, who only developed a mild disease 10 days after disease onset of the index case, did not have any contact with poultry and birds but had unprotected and very close contact with the index case. The sequences of the haemagglutinin (HA) genes of the virus stains isolated from the two cases were 100% identical. These findings strongly suggest that the second case might have acquired the infection via transmission of the virus from the sick father. Fortunately, all 40 close contacts, including the other four family members who also had unprotected and very close contact with the cases, did not acquire influenza A(H7N9) virus infection, indicating that the person-to-person transmissibility of the virus remained limited. Our finding underlines the importance of carefully, thoroughly and punctually following-up close contacts of influenza A(H7N9) cases to allow detection of any secondary cases, as these may constitute an early warning signal of the virus's increasing ability to transmit from person-to-person. .
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- Research articles
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Limited human-to-human transmission of avian influenza A(H7N9) virus, Shanghai, China, March to April 2013
In April 2013, two members of one family were successively confirmed as cases of avian influenza A(H7N9) virus infection in Shanghai, China. Respiratory specimens from the two cases and their close contacts were tested using real-time reverse-transcription (RT)-PCR. Paired serum specimens from contacts were tested by haemagglutination inhibition assay and microneutralisation test. The index patient developed severe pneumonia. Her husband presented with pneumonia shortly thereafter. Both cases had highly similar clinical features and infection with A(H7N9) virus was confirmed in both cases by genetic analysis. Phylogenetic analysis revealed a high level of similarity between the sequences from the two patients and environmental samples collected from wet markets in Minhang and Changning districts. Six samples from the Changning wet market were confirmed as A(H7N9) positive. Of 27 close contacts, one developed mild respiratory symptoms and another tested positive for A(H7N9) antibodies, but both were negative by real-time RT-PCR. The other 25 close contacts of both cases were A(H7N9) negative. Limited human-to-human transmission of the virus most likely occurred in the family cluster. However, other close contacts did not test positive for the virus, suggesting limited potential for extensive human-to-human transmission of the virus.
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Genetic tuning of the novel avian influenza A(H7N9) virus during interspecies transmission, China, 2013
D Wang , L Yang , R Gao , X Zhang , Y Tan , A Wu , W Zhu , J Zhou , S Zou , Xiyan Li , Y Sun , Y Zhang , Y Liu , T Liu , Y Xiong , J Xu , L Chen , Y Weng , X Qi , J Guo , Xiaodan Li , J Dong , W Huang , Y Zhang , L Dong , X Zhao , L Liu , J Lu , Y Lan , H Wei , L Xin , Y Chen , C Xu , T Chen , Y Zhu , T Jiang , Z Feng , W Yang , Y Wang , H Zhu , Y Guan , G F Gao , D Li , J Han , S Wang , G Wu and Y ShuA novel avian influenza A(H7N9) virus causing human infection emerged in February 2013 in China. To elucidate the mechanism of interspecies transmission, we compared the signature amino acids of avian influenza A(H7N9) viruses from human and non-human hosts and analysed the reassortants of 146 influenza A(H7N9) viruses with full genome sequences. We propose a genetic tuning procedure with continuous amino acid substitutions and reassorting that mediates host adaptation and interspecies transmission. When the early influenza A(H7N9) virus, containing ancestor haemagglutinin (HA) and neuraminidase (NA) genes similar to A/Shanghai/05 virus, circulated in waterfowl and transmitted to terrestrial poultry, it acquired an NA stalk deletion at amino acid positions 69 to 73. Then, receptor binding preference was tuned to increase the affinity to human-like receptors through HA G186V and Q226L mutations in terrestrial poultry. Additional mammalian adaptations such as PB2 E627K were selected in humans. The continual reassortation between H7N9 and H9N2 viruses resulted in multiple genotypes for further host adaptation. When we analysed a potential association of mutations and reassortants with clinical outcome, only the PB2 E627K mutation slightly increased the case fatality rate. Genetic tuning may create opportunities for further adaptation of influenza A(H7N9) and its potential to cause a pandemic.
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Genesis of the novel human-infecting influenza A(H10N8) virus and potential genetic diversity of the virus in poultry, China
Human infection with a novel influenza A(H10N8) virus was first described in China in December 2013. However, the origin and genetic diversity of this virus is still poorly understood. We performed a phylogenetic analysis and coalescent analysis of two viruses from the first case of influenza A(H10N8) (A/Jiangxi-Donghu/346-1/2013 and A/Jiangxi-Donghu/346-2/2013 and a novel A(H10N8) virus (A/chicken/Jiangxi/102/2013) isolated from a live poultry market that the patient had visited. The haemagglutinin (HA), neuraminidase (NA), PA subunit of the virus polymerase complex, nucleoprotein (NP), M and nonstructural protein (NS) genes of the three virus strains shared the same genetic origins. The origins of their HA and NA genes were similar: originally from wild birds to ducks, and then to chickens. The PA, NP, M, and NS genes were similar to those of chicken influenza A(H9N2) viruses. Coalescent analyses showed that the reassortment of these genes from A(H9N2) to A(H10N8) might have occurred at least twice. However, the PB1 and PB2 genes of the chicken A(H10N8) virus most likely originated from H7-like viruses of ducks, while those of the viruses from the case most likely stemmed from A(H9N2) viruses circulating in chickens. The oseltamivir-resistance mutation, R292K (R291K in A(H10N8) numbering) in the NA protein, occurred after four days of oseltamivir treatment. It seems that A(H10N8) viruses might have become established among poultry and their genetic diversity might be much higher than what we have observed.
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Volumes & issues
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Volume 29 (2024)
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Volume 28 (2023)
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Volume 27 (2022)
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Volume 26 (2021)
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Volume 25 (2020)
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Volume 24 (2019)
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Volume 23 (2018)
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Volume 22 (2017)
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Volume 21 (2016)
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Volume 20 (2015)
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Volume 19 (2014)
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Volume 18 (2013)
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Volume 17 (2012)
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Volume 16 (2011)
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Volume 15 (2010)
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Volume 14 (2009)
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Volume 13 (2008)
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Volume 12 (2007)
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Volume 11 (2006)
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Volume 10 (2005)
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Volume 9 (2004)
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Volume 8 (2003)
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Volume 7 (2002)
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Volume 6 (2001)
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Volume 5 (2000)
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Volume 4 (1999)
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Volume 3 (1998)
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Volume 2 (1997)
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Volume 1 (1996)
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Volume 0 (1995)
Most Read This Month
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Detection of 2019 novel coronavirus (2019-nCoV) by real-time RT-PCR
Victor M Corman , Olfert Landt , Marco Kaiser , Richard Molenkamp , Adam Meijer , Daniel KW Chu , Tobias Bleicker , Sebastian Brünink , Julia Schneider , Marie Luisa Schmidt , Daphne GJC Mulders , Bart L Haagmans , Bas van der Veer , Sharon van den Brink , Lisa Wijsman , Gabriel Goderski , Jean-Louis Romette , Joanna Ellis , Maria Zambon , Malik Peiris , Herman Goossens , Chantal Reusken , Marion PG Koopmans and Christian Drosten
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