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norovirus (Norwalk-like virus, winter vomiting disease)

Single-stranded RNA virus. Epidemiology: 1) transmitted by fecal oral route - most likely transmitted by contamination or food or water [2] - low inoculum required to produce infection [10] 2) persistence of virus on environmental surfaces [10] - frequently detected in the air of healthcare facilities during outbreaks, even outside patients' rooms [9] 3) second to the common cold as a cause of illness in the USA - most common cause of gastroenteritis in USA 4) only 10-100 organisms needed to cause infection 5) highly contagious, associated with epidemic outbreaks - GII.4 Sydney strain 2012 [6] 6) most common cause of gastroenteritis [4] - cause of > 50% of foodborne gastroenteritis in the U.S. [2] - 20% of gastroenteritis in children [7] - 18% of gastroenteritis worldwide [8] 7) viral shedding up to 2 weeks after symptom resolution [2] 8) infection does not produce lasting immunity [4] 9) norovirus outbreak at Grand Canyon affecting rafters & backpackers apparently transmitted via portable toilets [13] Pathology: 1) food poisoning 2) non-inflammatory diarrhea Clinical manifestations: 1) incubation time is > 14 hours - median incubation period of 24-48 hours - abrupt onset of symptoms 2) vomiting is predominant symptom 3) abdominal discomfort 4) mild to moderate non-inflammatory diarrhea (watery diarrhea) 5) fever (50%) 6) headache 7) symptoms may persist for 48-72 hours 8) dehydration may be life-threatening the young, elderly, immunocompromised Laboratory: 1) RT-PCR for norvirus RNA in stool 2) norovirus antigen in stool 3) norovirus in stool by electron microscopy 4) ELISA lacks sensitivity & specificity Complications: - among nursing home residents - 1 excess hospitalization for every 4 outbreaks - 1 excess death for every 9 outbreaks [5] - irritable bowel syndrome 12 months after infection (13%) Management: 1) self-limiting disorder, dehydration is a concern 2) handwashing & surface sanitization are the cornerstones of infection control 3) viral shedding up to 2 weeks after symptom resolution [2]

Specific

Norwalk virus

General

caliciviridae

Properties

KINGDOM: virus GENOME-TYPE: RNA SINGLE-STRANDED POSITIVE-STRAND GENOME-SIZE: 8 kB ENVELOPE: NONE CAPSID-SYMMETRY: ICOSAHEDRAL

References

  1. CDC, Division of viral diseases http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus.htm
  2. Medical Knowledge Self Assessment Program (MKSAP) 15, 17, 18, 19. American College of Physicians, Philadelphia 2009, 2015, 2018, 2021. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  3. Hall AJ et al Updated Norovirus Outbreak Management and Disease Prevention Guidelines MMWR March 4, 2011 / 60(RR03);1-15 PMID: 21368741 http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6003a1.htm
  4. Journal Watch, Massachusetts Medical Society, June 14, 2012 http://www.jwatch.org (subscription required) - Repp KK, Keene WE. A point-source norovirus outbreak caused by exposure to fomites. J Infect Dis 2012 Jun 1; 205:1639 PMID: 22573873 - Hall AJ. Noroviruses: The perfect human pathogens? J Infect Dis 2012 Jun 1; 205:1622 PMID: 22573872
  5. Trivedi TK et al Hospitalizations and Mortality Associated With Norovirus Outbreaks in Nursing Homes, 2009-2010 JAMA. Oct 18, 2012 PMID: 23079758 http://jama.jamanetwork.com/article.aspx
  6. Centers for Disease Control and Prevention Notes from the Field: Emergence of New Norovirus Strain GII.4 Sydney - United States, 2012 MMWR. January 25, 2013 / 62(03);55-55 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6203a4.htm
  7. Payne DC et al. Norovirus and medically attended gastroenteritis in U.S. children. N Engl J Med 2013 Mar 21; 368:1121. http://www.nejm.org/doi/full/10.1056/NEJMsa1206589
  8. Ahmed SM, Hall AJ, Robinson AE et al Global prevalence of norovirus in cases of gastroenteritis: a systematic review and meta-analysis. The Lancet Infectious Diseases. Online June 27, 2014 PMID: 24981041 http://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2814%2970767-4/abstract
  9. Bonifait L, Charlebois R, Vimont A et al Detection and Quantification of Airborne Norovirus During Outbreaks in Healthcare Facilities. Clin Infect Dis. 2015 Aug 1;61(3):299-304 PMID: 25900175
  10. NEJM Knoweledge+ Question of the Week. Sept 4, 2018 https://knowledgeplus.nejm.org/question-of-week/589/
  11. Glass RI, Parashar UD, Estes MK. Norovirus gastroenteritis. N Engl J Med. 2009 Oct 29;361(18):1776-85 PMID: 19864676 Free PMC Article https://www.nejm.org/doi/full/10.1056/NEJMra0804575
  12. Estes MK et al. Noroviruses everywhere: has something changed?. Curr Opin Infect Dis 2006 Aug 31; 19:467 PMID: 1694087
  13. Phillips J. CDC: 222 People at the Grand Canyon Got Sick With 'Explosive' Symptoms. The Epoch Times. Sept 30, 2022 https://www.theepochtimes.com/cdc-222-people-at-the-grand-canyon-got-sick-with-explosive-symptoms_4766488.html