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UK - Preliminary outbreak assessment for highly pathogenic avian influenza (H7N9) in poultry in the USA (DEFRA, March 15, 2017)

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  • UK - Preliminary outbreak assessment for highly pathogenic avian influenza (H7N9) in poultry in the USA (DEFRA, March 15, 2017)

    Research and analysis
    Avian influenza (bird flu) in poultry in the USA

    From: Department for Environment, Food & Rural Affairs and Animal and Plant Health Agency Part of: Animal diseases: international and UK monitoring and Animal and plant health First published: 15 March 2017

    Preliminary outbreak assessment for highly pathogenic avian influenza (H7N9) in poultry in the USA.

    Outbreaks of H7N9 avian influenza in poultry in the USA

    PDF, 215KB, 3 pages

    Department for Environment, Food and Rural Affairs
    Animal & Plant Health Agency
    Veterinary & Science Policy Advice Team - International Disease Monitoring
    Preliminary Outbreak Assessment
    Outbreaks of H7N9 avian influenza in poultry in the
    13th March 2017 Ref: VITT/1200 HPAI in USA

    Disease Report

    The USA has reported an outbreak of H7N9 HPAI in a commercial chicken broiler breeder
    flock in Lincoln County in the State of Tennessee (OIE, 2017a; see map). A small increase
    in mortality (700 of 74,000) was reported and tests confirmed HPAI. All birds have been
    culled and destroyed and disease control measures are in place, including a 10 mile (16
    km) surveillance zone. This is the first outbreak of HPAI in the USA this year. The National
    Veterinary Services Laboratory (NVSL) has confirmed this is a North American wild bird
    lineage, based on full genome sequencing and is not related to the Asian H7N9 LPAI /
    HPAI strain currently circulating in China (USDA, 2017). As part of routine surveillance at
    point of slaughter, H7N9 LPAI virus was also detected in a broiler breeder chicken flock
    also in Tennessee (Giles County) and the flock was depopulated (OIE, 2017b). Again, the
    origin of the virus was a North American wild bird lineage.

    In other reports, the USA has also detected H5N2 LPAI in a commercial turkey flock in
    Wisconsin (Barron County). This was a North American wild bird virus and is not related to
    the EA/AM H5N2 HPAI clade viruses which caused multiple cases in 2015 (OIE,

    Situation Assessment

    Tennessee and Wisconsin States are within the Mississippi Flyway for migratory wild
    birds. Therefore occasional incursions into poultry farms are not entirely unexpected.
    However, since the 2014-2015 epizootic in the USA, lessons were identified and an
    updated HPAI preparedness and response plan has been issued (APHIS, 2016).
    Export certificates for poultry and poultry products (under Commission Regulation
    798/2008/EC) have been suspended from the counties of Lincoln, Franklin and Moore in
    Tennessee and Madison and Jackson counties in Alabama. However, under
    regionalization agreements, consignments from other regions are accepted for export to
    the EU, including the UK.

    It is possible that the H7N9 HPAI virus was the result of an incursion of LPAI virus into the
    flock and consequent mutation into a highly pathogenic strain. It will be interesting to see if
    there is any evidence of this occurring.

    In Asia, the H7N9 virus which has been circulating in South East China for five years in
    poultry was recently sequenced from several poultry, environmental and human samples
    in Guangdong Province and Taiwan. Mutations in the HA gene suggested these strains
    could be highly pathogenic in gallinaceous poultry. If this were correct, it would mean
    surveillance could be targeted at clinical reports in poultry and allow controls to be put in
    place more readily. The European Centre for Disease Control has confirmed these
    mutations are not linked to any increase in affinity to mammalian cells and therefore no
    increase pathogenicity or spread in humans (FAO, 2017; ECDC, 2017).


    We will continue to monitor the situation and work with our partners to ensure we continue
    to trade safely. We would like to remind all poultry keepers and attending veterinarians to
    maintain high standards of biosecurity, remain vigilant and report any suspect clinical signs

    International Disease Monitoring Team

    "Safety and security don't just happen, they are the result of collective consensus and public investment. We owe our children, the most vulnerable citizens in our society, a life free of violence and fear."
    -Nelson Mandela