Norovirus infection

Last updated: July 20, 2022

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Noroviruses are a frequent cause of viral gastroenteritis in individuals of all ages worldwide. Transmission commonly occurs from person to person, as well as through contact with contaminated surfaces, food, and water. The clinical presentation of norovirus infection includes acute-onset vomiting and watery diarrhea. If classic clinical features of norovirus are present, treatment can usually be given without diagnostic confirmation; however, viral studies are recommended in certain cases, e.g., severe gastroenteritis, suspected outbreaks. Treatment is typically supportive (e.g., treatment of dehydration) as the condition normally self-resolves within 72 hours. Given its virulence and short incubation period, norovirus infection may quickly lead to outbreaks, which must be reported.

  • Peak incidence: November–March (winter months)
  • Community outbreaks (in nursing homes, hospitals, preschools, cruise ships, etc.) are common.
  • Older and immunocompromised patients are commonly affected.
  • Most common cause of:

References:[1][2][3]

Epidemiological data refers to the US, unless otherwise specified.

  • Pathogen: Norovirus; is a non‑enveloped RNA calicivirus.
  • Transmission
    • Fecal‑oral route through contaminated food or water, person‑to‑person contact, via airborne droplets, and contact with contaminated surfaces
    • The virus is highly virulent.
    • Individuals are highly infectious during the acute phase and 24–72 hours following onset of symptoms

Viral pathogens in gastroenteritis (Rotavirus is a Reovirus, Norovirus is a Calicivirus): Rotate Reo, the calico cat off to Norway!

References:[4]

  • Incubation period: 12–48 hours
  • Nausea and acute-onset vomiting
  • Watery, non-bloody diarrhea
  • Abdominal cramps
  • Fever
  • Symptoms resolve after 48–72 hours.

Overview [5][6]

  • Diagnosis is usually clinical; diagnostic studies are not required because confirmation does not affect management.
  • Consider diagnostic studies in the following: [5][6]
    • Patients with red flags for diarrhea or risk factors for severe infection
    • Diagnostic uncertainty
    • Concern for community or institutional outbreaks (see “Prevention”)

Suspect a possible norovirus outbreak if ≥ 2 patients with an epidemiological link present with symptoms of gastroenteritis within the same timeframe. [7]

Laboratory studies [3][8][9]

Whole stool is the preferred sample for viral testing. [3]

References:[10]

The differential diagnoses listed here are not exhaustive.

Treatment of norovirus infection is supportive; see also “Infectious gastroenteritis.”

Adults aged > 65 years are at increased risk for complications (e.g., dehydration, prolonged symptom duration) and thus more likely to require hospital admission. [13]

Prevention of norovirus transmission [3][7]

  • Educate on hand hygiene; wash hands with soap and water for at least 20 seconds:
    • Before preparing, touching, or eating food
    • Before giving medicines
    • After using the toilet or after any contact with vomit or feces (including changing infants' diapers)
  • Advise patients to:
    • Avoid preparing food for others until 48 hours after symptoms have resolved.
    • Disinfect bathrooms and high-touch surfaces with bleach-based cleaners.
    • Not share towels or linens
    • Wash contaminated towels, clothing, and bedding at the highest heat.
  • Recommend staying home for at least 48 hours after symptoms have resolved. [15]

Identification and management of outbreaks [3][7][15]

Norovirus is the most common cause of gastroenteritis outbreaks, which can be contained by early identification and management. [7]

  • Consider a possible outbreak if:
    • > 2 linked patients (e.g., travel on the same cruise ship, use of the same community pool) present with symptoms of gastroenteritis
    • Patients present with symptoms within 1–2 days of each other
  • Confirmation of norovirus
    • Viral studies including genotyping (see “Diagnostics of norovirus”) [8][9][16]
    • If viral studies are not possible, consider using the Kaplan criteria; norovirus is likely if: [7][15]
      • The mean or median duration of disease is 12–60 hours after an incubation period of 24–48 hours
      • More than 50% of affected patients have vomiting
      • No enteric bacteria have been detected.
  • Report all suspected outbreaks to the local health department.
  • Institutional outbreaks: See also “Infection prevention and control.” [15]

Norovirus can be transmitted via food, water, or from person to person, making it extremely contagious. Report all suspected outbreaks to local health departments. [3]

If food or water is suspected as the source of an outbreak, collect a specimen and contact local health authorities for further instructions. [3][17]

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  2. Norovirus - Burden of Norovirus Illness and Outbreaks. https://www.cdc.gov/norovirus/php/illness-outbreaks.html. Updated: July 8, 2014. Accessed: March 22, 2017.
  3. Hall AJ, Vinjé J, Lopman B et al . Updated Norovirus Outbreak Management and Disease Prevention Guidelines. Morbidity and Mortality Weekly Report. 2011; 60 (3): p.1-15.
  4. Hall AJ. Noroviruses: The Perfect Human Pathogens?. J Infect Dis. 2012; 205 (11): p.1622-1624. doi: 10.1093/infdis/jis251 . | Open in Read by QxMD
  5. Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea. Clin Infect Dis. 2017; 65 (12): p.e45-e80. doi: 10.1093/cid/cix669 . | Open in Read by QxMD
  6. Riddle MS, DuPont HL, Connor BA. ACG Clinical Guideline: Diagnosis, Treatment, and Prevention of Acute Diarrheal Infections in Adults. Am J Gastroenterol. 2016; 111 (5): p.602-622. doi: 10.1038/ajg.2016.126 . | Open in Read by QxMD
  7. Barclay L, Park GW, Vega E, et al. Infection control for norovirus. Clin Microbiol and Infect. 2014; 20 (8): p.731-740. doi: 10.1111/1469-0691.12674 . | Open in Read by QxMD
  8. Vinjé J. Advances in Laboratory Methods for Detection and Typing of Norovirus. J Clin Microbiol. 2015; 53 (2): p.373-381. doi: 10.1128/jcm.01535-14 . | Open in Read by QxMD
  9. Ludwig-Begall LF, Mauroy A, Thiry E. Noroviruses—The State of the Art, Nearly Fifty Years after Their Initial Discovery. Viruses. 2021; 13 (8): p.1541. doi: 10.3390/v13081541 . | Open in Read by QxMD
  10. Khan ZZ. Norovirus. In: Wallace MR, Norovirus. New York, NY: WebMD. http://emedicine.medscape.com/article/224225. Updated: October 20, 2015. Accessed: March 22, 2017.
  11. Barr W, Smith A. Acute diarrhea in adults. Am Fam Physician. 2014; 89 (3): p.180-189.
  12. Jameson JL, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J. Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2). McGraw-Hill Education / Medical ; 2018
  13. Cardemil CV, Parashar UD, Hall AJ. Norovirus Infection in Older Adults. Infect Dis Clin North Am. 2017; 31 (4): p.839-870. doi: 10.1016/j.idc.2017.07.012 . | Open in Read by QxMD
  14. Shah MP, Hall AJ. Norovirus Illnesses in Children and Adolescents. Infect Dis Clin North Am. 2018; 32 (1): p.103-118. doi: 10.1016/j.idc.2017.11.004 . | Open in Read by QxMD
  15. Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, 2011. https://www.cdc.gov/infectioncontrol/pdf/guidelines/norovirus-guidelines.pdf. Updated: May 4, 2011. Accessed: March 22, 2017.
  16. Norovirus - Diagnostic Methods. https://www.cdc.gov/norovirus/lab-testing/diagnostic.html. Updated: February 1, 2017. Accessed: March 22, 2017.
  17. Verhoef L, Hewitt J, Barclay L. Norovirus Genotype Profiles Associated with Foodborne Transmission, 1999–2012. Emerg Infect Dis. 2015; 21 (4): p.592-599. doi: 10.3201/eid2104.141073 . | Open in Read by QxMD
  18. Lucero Y, Matson DO, Ashkenazi S, George S, O’Ryan M. Norovirus: Facts and Reflections from Past, Present, and Future. Viruses. 2021; 13 (12): p.2399. doi: 10.3390/v13122399 . | Open in Read by QxMD
  19. Norovirus in Healthcare Facilities Fact Sheet. https://www.cdc.gov/hai/pdfs/norovirus/229110-ANoroCaseFactSheet508.pdf. Updated: September 6, 2011. Accessed: March 22, 2017.
  20. Drinking Water - Diseases and Contaminants. https://www.cdc.gov/healthywater/drinking/private/wells/disease/norovirus.html. Updated: July 1, 2015. Accessed: March 22, 2017.
  21. Haill CF, Newell P, Ford C et al. Compartmentalization of wards to cohort symptomatic patients at the beginning and end of norovirus outbreaks.. J Hosp Infect. 2012; 82 (1): p.30-35. doi: 10.1016/j.jhin.2012.05.015 . | Open in Read by QxMD
  22. Managing Norovirus Infections in Hospitals. http://www.confidenceconnected.com/blog/2012/09/12/managing_norovirus_infections_in_hospitals/. Updated: September 12, 2012. Accessed: March 22, 2017.
  23. Norovirus - Preventing Norovirus Infection. https://www.cdc.gov/norovirus/preventing-infection.html. Updated: July 15, 2016. Accessed: March 22, 2017.

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