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Preview: pubmed: H5N1 epidemiology

pubmed: H5N1 epidemiology



NCBI: db=pubmed; Term=H5N1 epidemiology



 



Comparative Epidemiology of Highly Pathogenic Avian Influenza Virus H5N1 and H5N6 in Vietnamese Live Bird Markets: Spatiotemporal Patterns of Distribution and Risk Factors.
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Comparative Epidemiology of Highly Pathogenic Avian Influenza Virus H5N1 and H5N6 in Vietnamese Live Bird Markets: Spatiotemporal Patterns of Distribution and Risk Factors.

Front Vet Sci. 2018;5:51

Authors: Mellor KC, Meyer A, Elkholly DA, Fournié G, Long PT, Inui K, Padungtod P, Gilbert M, Newman SH, Vergne T, Pfeiffer DU, Stevens KB

Abstract
Highly pathogenic avian influenza (HPAI) H5N1 virus has been circulating in Vietnam since 2003, whilst outbreaks of HPAI H5N6 virus are more recent, having only been reported since 2014. Although the spatial distribution of H5N1 outbreaks and risk factors for virus occurrence has been extensively studied, there have been no comparative studies for H5N6. Data collected through active surveillance of Vietnamese live bird markets (LBMs) between 2011 and 2015 were used to explore and compare the spatiotemporal distributions of H5N1- and H5N6-positive LBMs. Conditional autoregressive models were developed to quantify spatiotemporal associations between agroecological factors and the two HPAI strains using the same set of predictor variables. Unlike H5N1, which exhibited a strong north-south divide, with repeated occurrence in the extreme south of a cluster of high-risk provinces, H5N6 was homogeneously distributed throughout Vietnam. Similarly, different agroecological factors were associated with each strain. Sample collection in the months of January and February and higher average maximum temperature were associated with higher likelihood of H5N1-positive market-day status. The likelihood of market days being positive for H5N6 increased with decreased river density, and with successive Rounds of data collection. This study highlights marked differences in spatial patterns and risk factors for H5N1 and H5N6 in Vietnam, suggesting the need for tailored surveillance and control approaches.

PMID: 29675418 [PubMed]




Wild ducks excrete highly pathogenic avian influenza virus H5N8 (2014-2015) without clinical or pathological evidence of disease.
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Wild ducks excrete highly pathogenic avian influenza virus H5N8 (2014-2015) without clinical or pathological evidence of disease.

Emerg Microbes Infect. 2018 Apr 18;7(1):67

Authors: van den Brand JMA, Verhagen JH, Veldhuis Kroeze EJB, van de Bildt MWG, Bodewes R, Herfst S, Richard M, Lexmond P, Bestebroer TM, Fouchier RAM, Kuiken T

Abstract
Highly pathogenic avian influenza (HPAI) is essentially a poultry disease. Wild birds have traditionally not been involved in its spread, but the epidemiology of HPAI has changed in recent years. After its emergence in southeastern Asia in 1996, H5 HPAI virus of the Goose/Guangdong lineage has evolved into several sub-lineages, some of which have spread over thousands of kilometers via long-distance migration of wild waterbirds. In order to determine whether the virus is adapting to wild waterbirds, we experimentally inoculated the HPAI H5N8 virus clade 2.3.4.4 group A from 2014 into four key waterbird species-Eurasian wigeon (Anas penelope), common teal (Anas crecca), mallard (Anas platyrhynchos), and common pochard (Aythya ferina)-and compared virus excretion and disease severity with historical data of the HPAI H5N1 virus infection from 2005 in the same four species. Our results showed that excretion was highest in Eurasian wigeons for the 2014 virus, whereas excretion was highest in common pochards and mallards for the 2005 virus. The 2014 virus infection was subclinical in all four waterbird species, while the 2005 virus caused clinical disease and pathological changes in over 50% of the common pochards. In chickens, the 2014 virus infection caused systemic disease and high mortality, similar to the 2005 virus. In conclusion, the evidence was strongest for Eurasian wigeons as long-distance vectors for HPAI H5N8 virus from 2014. The implications of the switch in species-specific virus excretion and decreased disease severity may be that the HPAI H5 virus more easily spreads in the wild-waterbird population.

PMID: 29670093 [PubMed - in process]




Mutations in the PA Protein of Avian H5N1 Influenza Viruses Affect Polymerase Activity and Mouse Virulence.
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Mutations in the PA Protein of Avian H5N1 Influenza Viruses Affect Polymerase Activity and Mouse Virulence.

J Virol. 2018 02 15;92(4):

Authors: Zhong G, Le MQ, Lopes TJS, Halfmann P, Hatta M, Fan S, Neumann G, Kawaoka Y

Abstract
To study the influenza virus determinants of pathogenicity, we characterized two highly pathogenic avian H5N1 influenza viruses isolated in Vietnam in 2012 (A/duck/Vietnam/QT1480/2012 [QT1480]) and 2013 (A/duck/Vietnam/QT1728/2013 [QT1728]) and found that the activity of their polymerase complexes differed significantly, even though both viruses were highly pathogenic in mice. Further studies revealed that the PA-S343A/E347D (PA with the S-to-A change at position 343 and the E-to-D change at position 347) mutations reduced viral polymerase activity and mouse virulence when tested in the genetic background of QT1728 virus. In contrast, the PA-343S/347E mutations increased the polymerase activity of QT1480 and the virulence of a low-pathogenic H5N1 influenza virus. The PA-343S residue (which alone increased viral polymerase activity and mouse virulence significantly relative to viral replication complexes encoding PA-343A) is frequently found in H5N1 influenza viruses of several subclades; infection with a virus possessing this amino acid may pose an increased risk to humans.IMPORTANCE H5N1 influenza viruses cause severe infections in humans with a case fatality rate that exceeds 50%. The factors that determine the high virulence of these viruses in humans are not fully understood. Here, we identified two amino acid changes in the viral polymerase PA protein that affect the activity of the viral polymerase complex and virulence in mice. Infection with viruses possessing these amino acid changes may pose an increased risk to humans.

PMID: 29212927 [PubMed - indexed for MEDLINE]




Perceived Risk of Avian Influenza and Urbanization in Northern Vietnam.
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Perceived Risk of Avian Influenza and Urbanization in Northern Vietnam.

Ecohealth. 2017 03;14(1):144-154

Authors: Finucane ML, Tuyen N, Saksena S, Spencer JH, Fox JM, Lam N, Thau TD, Vien TD, Lewis ND

Abstract
Highly pathogenic avian influenza (HPAI) is an important public health concern because of potential for widespread morbidity and mortality in humans and poultry and associated devastating economic losses. We examined how perceptions of the risk of HPAI in poultry vary across communes/wards in the north of Vietnam at different levels of urbanization (rural, peri-urban, urban). Analyses of questionnaire responses from 1081 poultry raisers suggested that the perceived risk of HPAI in poultry was highest in peri-urban and rural settings. We also found that perceived risk was higher when respondents rated settings in which they did not live and that the process of change is related to perceived risk. Compared with others, respondents in peri-urban areas reported less disease management planning; respondents in rural areas reported less ability to separate infected poultry. These findings are consistent with, and add to, the limited previous research on the perceived risk of HPAI in poultry in developing countries. What is new in the present findings is that we describe how urbanization is related to people's perceptions of and ability to respond appropriately to variations in their environment. In particular, the inability to respond is not necessarily because of an inability to perceive change. Rather, rapid and extensive change poses different challenges for poultry management as communes move from rural to peri-urban to urban settings. Our results suggest that health promotion campaigns should address the perceptions and needs of poultry raisers in different settings.

PMID: 28213653 [PubMed - indexed for MEDLINE]