Announcement

Collapse
No announcement yet.

MMWR Morb Mortal Wkly Rep. Notes from the Field: Emergence of New Norovirus Strain GII.4 Sydney ? United States, 2012

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • MMWR Morb Mortal Wkly Rep. Notes from the Field: Emergence of New Norovirus Strain GII.4 Sydney ? United States, 2012

    [Source: US Centers for Disease Control and Prevention, MMWR Morbidity and Mortality Weekly Report, full page: (LINK). Edited.]
    Notes from the Field: Emergence of New Norovirus Strain GII.4 Sydney ? United States, 2012

    Weekly

    January 25, 2013 / 62(03);55-55



    Noroviruses are the leading cause of epidemic gastroenteritis, including foodborne outbreaks, in the United States (1). Hospitalization and mortality associated with norovirus infection occur most frequently among elderly persons, young children, and immunocompromised patients. Noroviruses belong to the family Caliciviridae and can be grouped into five genogroups (GI through GV), which are further divided into at least 34 genotypes. Human disease primarily is caused by GI and GII noroviruses, with most outbreaks caused by GII.4 strains (1). During the past decade, new GII.4 strains have emerged every 2?3 years, replacing previously predominant GII.4 strains. Emergence of these new norovirus strains has often, but not always, led to increased outbreak activity. For example, the previously dominant GII.4 New Orleans strain was not associated with increased norovirus outbreak activity in the United States (2). CDC collects information on norovirus strains associated with outbreaks in the United States through an electronic laboratory surveillance network called CaliciNet (3). This report documents the recent emergence of a new GII.4 strain, GII.4 Sydney, which caused most (53%) of the norovirus outbreaks reported through CaliciNet during September?December 2012. Continued surveillance will enable further assessment of the public health implications and significance of this new strain.

    In March 2012, a new GII.4 norovirus strain was identified in Australia. Named GII.4 Sydney, this emergent strain has since caused acute gastroenteritis outbreaks in multiple countries (4). In the United Kingdom, an early onset of the 2012 winter norovirus season was reported in association with emergence of GII.4 Sydney as the dominant strain implicated in outbreaks.* In the United States, GII.4 Sydney has spread rapidly nationwide, causing an increasing number of outbreaks.

    During September?December 2012, a total of 141 (53%) of the 266 norovirus outbreaks reported to CaliciNet were caused by GII.4 Sydney. The other outbreaks were caused by 10 different GI and GII genotypes, including GII.4 New Orleans. A statistically significant increase in the proportion of outbreaks caused by GII.4 Sydney was noted: four (19%) of 21 outbreaks in September 2012; 22 (46%) of 48 in October 2012; 70 (58%) of 120 in November 2012; and 45 (58%) of 77 in December 2012? (chi-square test for trend; p<0.01). Most (72 [51%]) of these GII.4 Sydney outbreaks resulted from direct person-to-person transmission; 29 (20%) were foodborne, one (1%) was waterborne, and the transmission mode was unknown in 39 (28%) of the outbreaks. Long-term?care facilities and restaurants were the most frequently reported settings, accounting for 91 (65%) and 18 (13%) of the GII.4 Sydney outbreaks, respectively. During the three previous winters, the peak in reported norovirus outbreaks occurred in January; therefore, at present, it is too early to make an assessment of the relative magnitude of the current season.

    GII.4 noroviruses remain the predominant cause of norovirus outbreaks, and the GII.4 Sydney strain appears to have replaced the previously predominant strain, GII.4 New Orleans. Compared with other norovirus genotypes, GII.4 noroviruses have been associated with increased rates of hospitalizations and deaths during outbreaks (5). Health-care providers and public health practitioners should remain vigilant to the potential for increased norovirus activity in the ongoing season related to the emergent GII.4 Sydney strain. Continued surveillance for norovirus outbreaks through CaliciNet and additional data on clinical and epidemiologic features of outbreaks collected through the National Outbreak Reporting System (NORS)? will enable further assessment of the public health implications of the new GII.4 Sydney strain, including any association with increased severity or level of activity in the ongoing 2012?13 winter norovirus season. Proper hand hygiene, environmental disinfection, and isolation of ill persons remain the mainstays of norovirus prevention and control (1).



    Reported by

    Leslie Barclay, Mary Wikswo, MPH, Nicole Gregoricus, MSPH, Jan Vinj?, PhD, Ben Lopman, PhD, Umesh Parashar, MBBS, Aron Hall, DVM, Div of Viral Diseases, National Center for Immunization and Respiratory Diseases; Eyal Leshem, MD, EIS officer, CDC. Corresponding contributor: Eyal Leshem, eleshem@cdc.gov, 404-639-7251.



    References
    1. CDC. Updated norovirus outbreak management and disease prevention guidelines. MMWR 2011;60(No. RR-3).
    2. Yen C, Wikswo ME, Lopman BA, Vinje J, Parashar UD, Hall AJ. Impact of an emergent norovirus variant in 2009 on norovirus outbreak activity in the United States. Clin Infect Dis 2011;53:568?71.
    3. Vega E, Barclay L, Gregoricus N, Williams K, Lee D, Vinje J. Novel surveillance network for norovirus gastroenteritis outbreaks, United States. Emerg Infect Dis 2011;17:1389?95.
    4. van Beek J, Ambert-Balay K, Botteldoorn N, et al. Indications for worldwide increased norovirus activity associated with emergence of a new variant of genotype II.4, late 2012. Euro Surveill 2013;18(1).
    5. Desai R, Hembree CD, Handel A, et al. Severe outcomes are associated with genogroup 2 genotype 4 norovirus outbreaks: a systematic literature review. Clin Infect Dis 2012;55:189?93.

    * Additional information available at http://www.hpa.org.uk/NewsCentre/NationalPressReleases/2013PressReleases/130109Norovirusnewstrain.

    ? Data for 2012 are incomplete.
    ? Additional information available at http://www.cdc.gov/nors.
    - ------

  • #2
    Re: MMWR Morb Mortal Wkly Rep. Notes from the Field: Emergence of New Norovirus Strain GII.4 Sydney ? United States, 2012

    hat tip Michael Coston

    MMWR Report On New Norovirus GII.4 Sydney Strain



    Norovirus ? Credit HPA


    # 6878

    Regular readers of this blog are aware that we?ve paid more attention this year to norovirus than in previous years, simply because there?s a lot of it going around this winter.

    In Eurosurveillance: Emergence & Spread Of GII.4 Variant Norovirus, we looked at early indications that a new variant of Norovirus was on the rise in Europe, and around the world.
    A few days later, I carried comments by the man who discovered this new strain - Professor Peter White, and his team in the School of Biotechnology and Biomolecular Sciences ? see (UNSW: Sydney 2012 Norovirus Rising).
    Noroviruses, which are often mistakenly called `stomach flu?, are single-stranded RNA viruses that are able to evolve rapidly, so we typically see a new dominant norovirus strain emerge every two or three years.
    Victims usually experience nausea, frequent vomiting & diarrhea, and stomach pain ? and may also suffer from headache, fever, and body aches.
    The illness generally runs its course in 1 to 3 (very long) days, and most people recover. But among those who are aged or infirmed, the virus can take a heavy toll. According to the CDC, each year the norovirus:
    • causes about 21 million cases of acute gastroenteritis (inflammation of the stomach or intestines or both)
    • contributes to about 70,000 hospitalizations and 800 deaths, mostly among young children and the elderly

    Today the CDC has confirmed what many have suspected; that this new Sydney strain of norovirus is contributing heavily to this year?s norovirus season here in the United States.

    In a press release mailed out today, the CDC previewed today?s MMWR report:
    New norovirus strain causing most norovirus outbreaks in United States
    Not yet known if strain will cause more outbreaks than previous years

    A new strain of norovirus called GII.4 Sydney was the leading cause of norovirus outbreaks in the United States from September to December 2012, according to a study published in Morbidity and Mortality Weekly Report released today by the Centers for Disease Control and Prevention. The new strain was detected in Australia in March 2012, and caused outbreaks in that country and several other countries.

    CDC researchers analyzed 2012 data collected through CaliciNet on norovirus strains associated with outbreaks in the United States. They found that of the 266 norovirus outbreaks reported during the last four months of 2012, 141 were caused by the GII.4 Sydney strain.

    ?The new strain spread rapidly across the United States from September to December 2012,? said Dr. Aron Hall, epidemiologist, CDC?s Division of Viral Diseases (DVD). ?The proportion of reported outbreaks caused by this strain increased dramatically from 19 percent in September to 58 percent in December

    A link to and excerpt from today?s MMWR.

    Notes from the Field: Emergence of New Norovirus Strain GII.4 Sydney ? United States, 2012

    Weekly

    January 25, 2013 / 62(03);55-55 EXCERPT
    GII.4 noroviruses remain the predominant cause of norovirus outbreaks, and the GII.4 Sydney strain appears to have replaced the previously predominant strain, GII.4 New Orleans. Compared with other norovirus genotypes, GII.4 noroviruses have been associated with increased rates of hospitalizations and deaths during outbreaks (5). Health-care providers and public health practitioners should remain vigilant to the potential for increased norovirus activity in the ongoing season related to the emergent GII.4 Sydney strain.

    Continued surveillance for norovirus outbreaks through CaliciNet and additional data on clinical and epidemiologic features of outbreaks collected through the National Outbreak Reporting System (NORS)? will enable further assessment of the public health implications of the new GII.4 Sydney strain, including any association with increased severity or level of activity in the ongoing 2012?13 winter norovirus season. Proper hand hygiene, environmental disinfection, and isolation of ill persons remain the mainstays of norovirus prevention and control (1).

    One of the keys to prevention is good hand hygiene, unfortunately, unlike with many other bacteria and viruses, alcohol gel doesn?t do a particularly good job of killing the virus (see CMAJ: Hand Sanitizers May Be `Suboptimal? For Preventing Norovirus).

    The CDC offers this advice to help prevent the spread of this virus.



    Posted by Michael Coston at <a class="timestamp-link" href="http://afludiary.blogspot.com/2013/01/mmwr-report-on-new-norovirus-gii4.html" rel="bookmark" title="permanent link"><abbr class="published" title="2013-01-24T12:24:00-05:00">12:24 PM</abbr>

    Comment

    Working...
    X