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US isues warning about novel H3N1 viruses in swine containing the HA from seasonal H3N2 human flu

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  • US isues warning about novel H3N1 viruses in swine containing the HA from seasonal H3N2 human flu

    Uh oh.

    Published Date: 2014-09-16 08:51:13
    Subject: PRO/AH/EDR> Influenza, swine - USA: novel strains, H3N1, alert
    Archive Number: 20140916.2776180

    A ProMED-mail post
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    Date: Thu 11 Sep 2014
    From: Christina M Loiacono <> [edited]

    This email has been provided to all SIV (swine influenza virus) approved NAHLN (National Animal Health Laboratory Network) labs

    Dear NAHLN laboratory director,

    The USDA IAV-S surveillance (IAV-S is the influenza A virus in swine) program has identified several H3N1's in US swine in at least 2 states since December 2013. Although this is not the 1st time H3N1's have been detected in swine in the US, it is a rare occurrence and needs further examination. More importantly, 2 of these H3N1's carry a novel human seasonal HA gene from contemporary human viruses and are distinct from our current swine H3 viruses. A review of Genbank data indicates there may be more human-like H3 genes (in either H3N1 or H3N2) circulating in US swine subtypes than what the USDA surveillance data has captured. Potential spread of H3N1 or H3N2 that carries the human-like H3 could have significant impact in swine herds due to poor herd immunity as well as potential public health ramifications. Preliminary findings by USDA-ARS [Agricultural Research Service] from testing of one of these H3N1 isolates with the human-like H3 gene in swine indicate the virus is fully virulent, causing typical influenza disease.

    We are sharing this information to alert producers, veterinarians, and National Animal Health Laboratory Network labs of this occurrence. The surveillance program for IAV-S in swine was established to:
    - monitor the genetic evolution of endemic IAV-S to better understand endemic and emerging influenza virus ecology,
    - make IAV-S isolates and associated epidemiologic data available for research and analysis, and
    - select proper isolates for the development of relevant diagnostic reagents, updating diagnostic assays, and vaccine seed stock products in swine.

    The identification of this new human-like H3 in swine subtypes is a key example of how IAV-S surveillance can benefit swine health.

    We are anticipating that additional information about swine subtypes carrying the human like H3 will be captured through the surveillance system to assist in determining how widespread the virus is and whether additional actions may be needed by veterinarians, producers, and vaccine manufacturers.

    As a reminder, if an isolate is obtained from an alternative methodology than the NAHLN algorithm, the isolate is eligible for submission to the USDA IAV-S surveillance system. The isolate can be subtyped and sequenced (H, M, N), sequences deposited into GenBank, and the isolate submitted to the USDA IAV-S repository; the subtyping and sequencing and the isolate will be eligible for reimbursement from NAHLN; however the alternative methods will NOT be subject for reimbursement.

    Christina M Loiacono, DVM, PhD, DACVP
    Associate Coordinator
    National Animal Health Laboratory Network
    1920 Dayton Road, Ames, IA

    Communicated by:

    [This is a serious alert. It is especially concerning as we enter the autumn livestock show and fair season. Animals congregate at these gatherings, as do people. The opportunity for viral spread and viral assortment at these shows is quite large.

    Extreme caution is needed as even healthy appearing animals can be incubating and spreading disease.

    If your animal or your family member is ill, please exercise caution and keep them home. Travel can stress the immune system in an unfavorable way. Likewise, it would be unwise to spread a virus that could be very, very serious to all concerned.

    ProMED-mail Rapporteur Mary Marshall submitted the same advisory from the USDA Animal and Plant Health Inspection Service, published in National Hog Farmer
    - Mod.TG]