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Nebraska Protocol for Suspected AI in Poultry

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  • Nebraska Protocol for Suspected AI in Poultry

    State prepares for bird flu outbreak

    Publication Date: 08/19/2007
    LINCOLN Routine testing for avian influenza, or the bird flu, at the University of Nebraska-Lincoln's Veterinary Diagnostic Center means producers get the information they need fast.
    When it comes to poultry, time is of the essence, said David Steffen, director of UNL's Veterinary Diagnostic Center, who for the last three years has served on the Nebraska Department of Agriculture's Poultry Livestock Health Committee.
    The committee is in charge of a bird flu response plan that outlines what would happen if a highly pathogenic strain of the virus were to hit the state. In addition to the high-path influenza response plan, the center conducts testing to support a voluntary surveillance program for low path bird flu. This virus causes no risk to birds or people but is of concern as influenza viruses can recombine genes among various strains and potentially become more serious.
    The case of bird flu that was discovered recently on a poultry farm near Seward had a screening test for avian influenza come back positive. This indicated the birds had been exposed to the virus.
    "Rapid testing was very important as we needed to determine what strain of virus had been present and to determine if active virus was present in birds being sent for processing. Poultry operations are closely orchestrated production systems with birds contracted for slaughter and for replacement chicks based on normal growth. This scheduling is closely coordinated," Steffen said. "So the actions resulting from test reports not only impact the producer, but the hatching facility and the slaughter plant as well.
    "If the turkeys can't go to slaughter, those employees don't have any birds that day, and the producers may not have a vacant barn to place new chicks. It really is important to have rapid, accurate testing available within the state."
    With the recent positive test, the blood sample then was sent to the National Veterinary Services Laboratory in Ames, Iowa, to determine the bird flu strain.

    The strain was an H7N9 and was low path, meaning it was not a threat to human health and did not cause clinical disease in the birds.

    The national lab provides the definitive tests, but the in-state results are available a day sooner and help the owner and regulatory personnel stage their response.

    "The molecular analysis of the virus is accurate, but there are some isolates that don't behave like we expect," Steffen said. "For example, the avian influenza virus that was found in Texas was a high-path virus based on molecular testing but when it was put into birds it didn't kill them like they thought it would. As with most diseases, we don't fully understand all the dynamics of the agents."

    This makes the full battery of tests essential to understand an outbreak.

    Not all strains of bird flu cause concern. Those with H5 or H7 surface proteins could recombine with other viruses and have a higher probability of becoming highly pathogenic when that happens, Steffen said.
    H5 N1 is the strain that was transmitted to people in Asia. The virus near Seward was an H7 strain.

    "The flock was exposed weeks before detection and birds going to slaughter are immune rather than infected," Steffen said. Turkeys typically are brought to slaughter at age 15 to 17 weeks and those birds tested have not had active virus present, making them safe for processing and consumption.

    Until the flock is cleared of virus, the Seward flock remains quarantined. Low-path avian influenza virus occurs most often in wild and migratory birds and is part of the natural ecosystem of migratory birds as waterfowl are the natural hosts for the virus.

    The diagnostic center is part of the university's Institute of Agriculture and Natural Resources.

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