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US CDC, MMWR 11/24/10: Three human infections with triple reassortant H3N2 influenza virus reported in 2010.

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  • US CDC, MMWR 11/24/10: Three human infections with triple reassortant H3N2 influenza virus reported in 2010.

    See this week MMWR Morbidity and Mortality Weekly Report: http://www.cdc.gov/mmwr/PDF/wk/mm5946.pdf (pag. 1525)



    (???) CDC discontinued reporting of individual confirmed and probable cases of 2009 pandemic influenza A (H1N1) virus infections on July 24, 2009. During 2009, four cases of human infection with novel influenza A viruses, different from the 2009 pandemic influenza A (H1N1) strain, were reported to CDC. The three cases of novel influenza A virus infection reported to CDC during 2010 were identified as swine influenza A (H3N2) virus and are unrelated to the 2009 pandemic influenza A (H1N1) virus. Total case counts for 2009 were provided by the Influenza Division, National Center for Immunization and Respiratory Diseases (NCIRD).
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  • #2
    Re: US CDC, MMWR 11/24/10: Three human infections with triple reassortant H3N2 influenza virus reported in 2010.

    From November 24 World Health Organization Influenza Update:

    Source: WHO (http://www.who.int/csr/disease/influ.../en/index.html )
    At FluTrackers: (http://www.flutrackers.com/forum/sho...77&postcount=1 )

    (...)

    Human infections with other influenza viruses:

    Swine-origin H3N2 virus infection in the US

    On 12 November, 2010, the United States Centers for Disease Control and Prevention (US CDC), reported two sporadic cases of human infection with triple reassortant swine origin influenza A(H3N2) viruses. The two cases occurred in separate states, are not believed to be epidemiologically linked to each other, and both occurred in the vicinity of live pigs. Both patients have fully recovered from their illness.

    The viruses isolated from both patients had some genetic differences further suggesting that two cases were not linked.

    Investigations thus far have not shown any evidence of community transmission of these viruses.

    For more information visit: (LINK) or (LINK)

    The first detection in a human of the triple reassortant swine A(H3N2) virus was in 2005 in Ontario Canada. Since then human cases have been reported nearly every year. All cases have fully recovered and no increased severity has been associated with the infection with these viruses in humans.

    In North America, A(H3N2) viruses in pigs emerged around 1998-99, when the human influenza A(H3N2) viruses entered into swine population and reassorted with other influenza viruses already circulating in pigs. The A(H3N2) viruses currently circulating in the swine population in US and Canada contain gene segments from avian-like, swine-like, and human-like viruses.

    Early identification and investigation of human infections with novel influenza A viruses is critical to evaluate the extent of the outbreak and possible human-to-human transmission and WHO continues to encourage member states to investigate and report these events.

    (...)
    -
    ------

    Comment


    • #3
      Re: US CDC, MMWR 11/24/10: Three human infections with triple reassortant H3N2 influenza virus reported in 2010.

      Discussion of other 2 cases here:

      USA - H3N2 swine flu in 2 human cases, "vicinity" of pigs cited - CDC




      Again, we ask for release of all epidemiological information relating to these cases.

      Comment


      • #4
        Re: US CDC, MMWR 11/24/10: Three human infections with triple reassortant H3N2 influenza virus reported in 2010.

        Originally posted by sharon sanders View Post
        Discussion of other 2 cases here:

        USA - H3N2 swine flu in 2 human cases, "vicinity" of pigs cited - CDC




        Again, we ask for release of all epidemiological information relating to these cases.
        The two cases in that thread are cases #2 and #3 chronologically, I believe. The first case was in January 2010, I believe. This MMWR does not appear to contain any additional cases beyond those previously announced.

        Comment


        • #5
          Re: US CDC, MMWR 11/24/10: Three human infections with triple reassortant H3N2 influenza virus reported in 2010.

          Suggested citations:

          (1) US Centers for Diseases Control and Prevention, Have you Heard? Nov 12 2010, http://www.cdc.gov/media/subtopic/heard.htm#h3n2

          (2) US Centers for Diseases Control and Prevention, FluView Week 44, Nov. 6 2010, http://www.cdc.gov/flu/weekly/

          (3) World Health Organization, Influenza Update no. 120, Nov. 22 2010, http://www.who.int/csr/disease/influ.../en/index.html


          Excerpts:

          (...)

          Human infections with other influenza viruses:

          Swine-origin H3N2 virus infection in the US

          On 12 November, 2010, the United States Centers for Disease Control and Prevention (US CDC), reported two sporadic cases of human infection with triple reassortant swine origin influenza A(H3N2) viruses. The two cases occurred in separate states, are not believed to be epidemiologically linked to each other, and both occurred in the vicinity of live pigs. Both patients have fully recovered from their illness.

          The viruses isolated from both patients had some genetic differences further suggesting that two cases were not linked.

          Investigations thus far have not shown any evidence of community transmission of these viruses.

          For more information visit: (LINK) or (LINK)

          The first detection in a human of the triple reassortant swine A(H3N2) virus was in 2005 in Ontario Canada. Since then human cases have been reported nearly every year. All cases have fully recovered and no increased severity has been associated with the infection with these viruses in humans.

          In North America, A(H3N2) viruses in pigs emerged around 1998-99, when the human influenza A(H3N2) viruses entered into swine population and reassorted with other influenza viruses already circulating in pigs. The A(H3N2) viruses currently circulating in the swine population in US and Canada contain gene segments from avian-like, swine-like, and human-like viruses.

          Early identification and investigation of human infections with novel influenza A viruses is critical to evaluate the extent of the outbreak and possible human-to-human transmission and WHO continues to encourage member states to investigate and report these events.(3)

          (...)

          -

          (...)

          November 12, 2010

          Reports of Human Infections with Swine Origin Influenza A (H3N2)


          The November 12, 2010 FluView reports two human infections with swine origin influenza A (H3N2) viruses in the United States.

          Test samples from two patients submitted by Wisconsin and Pennsylvania have been confirmed at CDC as positive for swine origin triple-reassortant (tr) H3N2 influenza viruses?viruses that normally infect pigs.

          While human infection with swine influenza viruses is rare, it can occur.

          This is most likely to occur when people are in close proximity to infected pigs, such as in pig barns and livestock exhibits housing pigs at fairs.

          Both of the patients with confirmed trH3N2 infection reported in FluView were in the vicinity of live pigs.

          Dates of illness onset in the two patients are more than six weeks apart and the viruses from the two patients have some genetic differences, confirming that these two cases are not linked.

          Ongoing investigations in both states have not shown any evidence of community transmission of these viruses.

          The most likely scenario at this point is that these are two isolated cases of human infection with swine influenza viruses that, while very rare, do occur from time to time.

          (...)

          The viruses identified in Pennsylvania and Wisconsin are similar to viruses that infected a patient in Iowa in September 2009, a patient in Kansas in August 2009 and a patient in Minnesota in May 2010.

          (...)

          The patient in Pennsylvania lives in an area where live pigs are farmed and the patient in Wisconsin became sick two days after attending a state fair where pigs were exhibited. (1)

          -

          (...)

          Novel Influenza A Virus:

          Two cases of human infection with a novel influenza A virus were reported: one case by the Wisconsin Department of Health Services and one case by the Pennsylvania Department of Health.

          Both patients were infected with a swine origin influenza A (H3N2) virus similar to the three other swine origin influenza A (H3N2) viruses previously identified in 2009 and 2010.

          The Wisconsin case reported contact with pigs
          in the week preceding symptom onset on September 8, 2010 and required hospitalization.

          No contact with pigs has been identified in the Pennsylvania case
          in the week before symptom onset on October 24, 2010; however the case lives in an area close to pig farms.

          Both patients have fully recovered
          from their illness.

          The cases are not related and the viruses from these two cases have some genetic differences, indicating that they did not come from the same source.

          Although both investigations are ongoing, there is no evidence of human-to-human transmission with this virus in either case.

          Early identification and investigation of human infections with novel influenza A viruses is critical to evaluate the extent of the outbreak and possible human-to-human transmission.

          Surveillance for human infections with novel influenza A viruses continues year round.

          For additional information on these cases and swine influenza, see (LINK).(2)

          (...)
          -
          ------

          Comment


          • #6
            Re: US CDC, MMWR 11/24/10: Three human infections with triple reassortant H3N2 influenza virus reported in 2010.

            Thank you everyone.

            I have moved this thread into the US forum and made it sticky so that we can more efficiently track.

            Comment


            • #7
              Re: US CDC, MMWR 11/24/10: Three human infections with triple reassortant H3N2 influenza virus reported in 2010.

              Moved to new trH3N2 forum last week.

              Please also see:

              Mongolia recorded "unknown" influenza virus

              Comment

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