Norovirus

Source: Wikipedia, the free encyclopedia.

Norovirus
Other namesWinter vomiting bug,
intravenous fluids)[5]
Frequency685 million cases per year[6]
Deaths200,000 per year[6][7]

Norovirus, also known as Norwalk virus and sometimes referred to as the winter vomiting disease, is the most common cause of

stomach pain.[2][3] Fever or headaches may also occur.[2] Symptoms usually develop 12 to 48 hours after being exposed, and recovery typically occurs within one to three days.[2] Complications are uncommon, but may include dehydration, especially in the young, the old, and those with other health problems.[2]

The

close quarters.[3] Diagnosis is generally based on symptoms.[3] Confirmatory testing is not usually available but may be performed by public health agencies during outbreaks.[3]

Prevention involves proper

Alcohol-based hand sanitizers are not effective against the norovirus, according to the NHS information page on the subject;[8] this is due to norovirus being a non-enveloped virus
.

Norovirus results in about 685 million cases of disease and 200,000 deaths globally a year.

foodborne disease outbreaks.[3] The virus is named after the city of Norwalk, Ohio, US, where an outbreak occurred in 1968.[10]

Signs and symptoms

Norovirus infection is characterized by nausea, vomiting, watery diarrhea, abdominal pain, and in some cases, loss of taste. A person usually develops symptoms of gastroenteritis 12 to 48 hours after being exposed to norovirus.[11] General lethargy, weakness, muscle aches, headaches, and low-grade fevers may occur. The disease is usually self-limiting, and severe illness is rare. Although having norovirus can be unpleasant, it is not usually dangerous, and most who contract it make a full recovery within two to three days.[1]

Norovirus can establish a long-term infection in people who are

intestinal villous atrophy, and malabsorption.[12]

Virology

Norovirus
Transmission electron micrograph of Norovirus particles in feces
Transmission electron micrograph
of Norovirus particles in feces
Virus classification Edit this classification
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Pisuviricota
Class: Pisoniviricetes
Order: Picornavirales
Family: Caliciviridae
Genus: Norovirus
Species:
Norwalk virus

Transmission

Noroviruses are transmitted directly from person to person (62–84% of all reported outbreaks)

aerosolized when those stricken with the illness vomit or by a toilet flush when vomit or diarrhea is present; infection can follow eating food or breathing air near an episode of vomiting, even if cleaned up.[16] The viruses continue to be shed after symptoms have subsided, and shedding can still be detected many weeks after infection.[17]

Vomiting, in particular, transmits infection effectively and appears to allow airborne transmission. In one incident, a person who vomited spread the infection across a restaurant, suggesting that many unexplained cases of food poisoning may have their source in vomit.[18] In December 1998, 126 people were dining at six tables; one person vomited onto the floor. Staff quickly cleaned up, and people continued eating. Three days later others started falling ill; 52 people reported a range of symptoms, from fever and nausea to vomiting and diarrhea. The cause was not immediately identified. Researchers plotted the seating arrangement: more than 90% of the people at the same table as the sick person later reported becoming ill. There was a direct correlation between the risk of infection of people at other tables and how close they were to the sick person. More than 70% of the diners at an adjacent table fell ill; at a table on the other side of the restaurant, the infection rate was still 25%. The outbreak was attributed to a Norwalk-like virus (norovirus). Other cases of transmission by vomit were later identified.[19]

In one outbreak at an international scout

mode of transmission as person-to-person in seven outbreaks, foodborne in two, waterborne in one, and one unknown. The source of waterborne outbreaks may include water from municipal supplies, wells, recreational lakes, swimming pools, and ice machines.[21]

Shellfish and salad ingredients are the foods most often implicated in norovirus outbreaks. Ingestion of shellfish that has not been sufficiently heated – under 75 °C (167 °F) – poses a high risk for norovirus infection.[22][23] Foods other than shellfish may be contaminated by infected food handlers.[24] Many norovirus outbreaks have been traced to food that was handled by only one infected person.[25]

Between March and August 2017, in Quebec, Canada, there was an outbreak of norovirus that sickened more than 700 people. According to an investigation by Canada's CFIA Food Control Agency, the culprit was frozen raspberries imported from Harbin Gaotai Food Co Ltd, a Chinese supplier, and then Canadian authorities issued a recall on raspberries products from Harbin Gaotai.[26]

According to the CDC, there was a surge in norovirus cases on thirteen cruise ships in 2023, which marks the highest number of outbreaks since 2012.[27]

Classification

Noroviruses (NoV) are a genetically diverse group of single-stranded

enveloped viruses belonging to the family Caliciviridae.[28][29] According to the International Committee on Taxonomy of Viruses, the genus Norovirus has one species, which is called Norwalk virus.[28]

Noroviruses can genetically be classified into at least seven different genogroups (GI, GII, GIII, GIV, GV, GVI, and GVII), which can be further divided into other genetic clusters or genotypes.[30]

Noroviruses commonly isolated in cases of acute gastroenteritis belong to two genogroups: genogroup I (GI) includes Norwalk virus, Desert Shield virus, and Southampton virus; and II (GII), which includes Bristol virus, Lordsdale virus, Toronto virus, Mexico virus, Hawaii virus and Snow Mountain virus.[29]

Most noroviruses that infect humans belong to genogroups GI and GII.[31] Noroviruses from genogroup II, genotype 4 (abbreviated as GII.4) account for the majority of adult outbreaks of gastroenteritis and often sweep across the globe.[32]

Recent examples include US95/96-US strain, associated with global outbreaks in the mid- to late-1990s;

bile salts may facilitate the infection, making it more intense when introduced during or after the initial infection of the host tissue.[35] Bile salts are produced by the liver in response to eating fatty foods, and they help with the absorption of consumed lipids. It is not yet clear as to at what specific point in the Norovirus replication cycle bile salts facilitate infection: penetration, uncoating, or maintaining capsid stability.[35]

The protein

MDA-5 may be the primary immune sensor that detects the presence of noroviruses in the body.[36] Some people have common variations of the MDA-5 gene that could make them more susceptible to norovirus infection.[37]

Structure

X-ray crystallographic structure of the Norwalk virus capsid
Genus Structure Symmetry Capsid Genomic arrangement Genomic segmentation
Norovirus Icosahedral T=1, T=3 Non-enveloped Linear Monopartite

Viruses in Norovirus are non-enveloped, with

electron microscopy.[39]

Genome

Noroviruses contain a linear, non-segmented,

The most variable region of the viral capsid is the P2

domain, which contains antigen-presenting sites and carbohydrate-receptor binding regions.[42][43][44][45][46]

Evolution

Groups 1, 2, 3, and 4 last shared a

common ancestor in AD 867.[47] The group 2 and group 4 viruses last shared a common ancestor in approximately AD 1443 (95% highest posterior density AD 1336–1542).[48] Several estimates of the evolution rate have been made varying from 8.98 × 10−3 to 2.03 × 10−3 substitutions per site per year.[citation needed
]

The estimated mutation rate (1.21×10−2 to 1.41 ×10−2 substitutions per site per year) in this virus is high even compared with other RNA viruses.[49]

In addition, a recombination hotspot exists at the ORF1-ORF2 (VP1) junction.[50]

Replication cycle

natural host. Transmission routes are fecal-oral and contamination.[38]

Genus Host details Tissue tropism Entry details Release details Replication site Assembly site Transmission
Norovirus Humans; mammals Intestinal epithelium Cell receptor endocytosis Lysis Cytoplasm Cytoplasm Oral-fecal

Pathophysiology

When a person becomes infected with norovirus, the virus replicates within the small intestine. The principal symptom is acute gastroenteritis, characterized by nausea, forceful vomiting, watery diarrhea, and abdominal pain, that develops between 12 and 48 hours after exposure, and lasts for 24–72 hours.[51] Sometimes there is loss of taste, general lethargy, weakness, muscle aches, headache, cough, and/or low-grade fever. The disease is usually self-limiting.[citation needed]

Severe illness is rare; although people are frequently treated at the emergency ward, they are rarely admitted to the hospital. The number of deaths from norovirus in the United States is estimated to be around 570–800[52] each year, with most of these occurring in the very young, the elderly, and persons with weakened immune systems. Symptoms may become life-threatening in these groups if dehydration or electrolyte imbalance is ignored or left untreated.[53]

Diagnosis

Specific diagnosis of norovirus is routinely made by

quantitative PCR assays, which give results within a few hours. These assays are very sensitive and can detect as few as 10 virus particles.[54]
Tests such as ELISA that use antibodies against a mixture of norovirus strains are available commercially, but lack specificity and sensitivity.[55]

Prevention

After

immunity to the same strain of the virus – the genotype – protects against reinfection for between six months to two years.[56] This immunity does not fully protect against infection with the other diverse genotypes of the virus.[56]

In Canada, norovirus is a notifiable disease.[57] In both the US and the UK it is not notifiable.[58][59]

Hand washing and disinfectants

Hand washing with soap and water is an effective method for reducing the transmission of norovirus pathogens. Alcohol rubs (≥62% isopropyl alcohol) may be used as an adjunct, but are less effective than hand-washing, as norovirus lacks a lipid viral envelope.[60] Surfaces where norovirus particles may be present can be sanitised with a solution of 1.5% to 7.5% of household bleach in water, or other disinfectants effective against norovirus.[51][61][62]

Health care facilities

In healthcare environments, the prevention of

Nonflammable alcohol vapor in CO2 systems is used in health care environments where medical electronics would be adversely affected by aerosolized chlorine or other caustic compounds.[63]

In 2011, the CDC published a clinical practice guideline addressing strategies for the prevention and control of norovirus gastroenteritis outbreaks in healthcare settings.[64][65] Based on a systematic review of published scientific studies, the guideline presents 51 specific evidence-based recommendations, which were organized into 12 categories: 1) patient cohorting and isolation precautions, 2) hand hygiene, 3) patient transfer and ward closure, 4) food handlers in healthcare, 5) diagnostics, 6) personal protective equipment, 7) environmental cleaning, 8) staff leave and policy, 9) visitors, 10) education, 11) active case-finding, and 12) communication and notification. The guideline also identifies eight high-priority recommendations and suggests several areas in need of future research.[citation needed]

Vaccine trials

LigoCyte announced in 2007 that it was working on a vaccine and had started phase 1 trials.[66] The company has since been taken over by Takeda Pharmaceutical Company.[67] As of 2019, a bivalent (NoV GI.1/GII.4) intramuscular vaccine had completed phase 1 trials.[68][69] In 2020 the phase 2b trials were finished.[70][71] The vaccine relies on using a virus-like particle that is made of the norovirus capsid proteins in order to mimic the external structure of the virus. Since there is no RNA in this particle, it is incapable of reproducing and cannot cause an infection.[66]

Persistence

The norovirus can survive for long periods outside a human host depending on the surface and temperature conditions: it can survive for weeks on hard and soft surfaces,[72] and it can survive for months, maybe even years in contaminated still water.[73] A 2006 study found the virus remained on surfaces used for food preparation seven days after contamination.[74]

Detection in food

Routine protocols to detect norovirus in clams and oysters by reverse transcription polymerase chain reaction are being employed by governmental laboratories such as the Food and Drug Administration (FDA) in the US.[75]

Treatment

There is no specific medicine to treat people with norovirus illness. Norovirus infection cannot be treated with antibiotics because it is a virus. Treatments aim to avoid complications by measures such as the

antidiarrheals.[76]

Epidemiology

Annual Trend in Reports of Norovirus Infection in England and Wales (2000–2011). Source: HPA
Laboratory reports of norovirus infections in England and Wales 2000–2012. Source: HPA, NB Testing methods changed in 2007.[77]

Norovirus causes about 18% of all cases of acute gastroenteritis worldwide. It is relatively common in developed countries and in low-mortality developing countries (20% and 19% respectively) compared to high-mortality developing countries (14%). Proportionately it causes more illness in people in the community or in hospital outpatients (24% and 20% respectively) as compared with hospital inpatients (17%) in whom other causes are more common.[78]

Age and emergence of new norovirus strains do not appear to affect the proportion of gastroenteritis attributable to norovirus.[78]

Norovirus is a common cause of epidemics of gastroenteritis on cruise ships. The CDC, through its Vessel Sanitation Program, records and investigates outbreaks of gastrointestinal illness – mostly caused by norovirus – on cruise ships with both a US and foreign itinerary;[79] there were 12 in 2015, and 10 from 1  January to 9  May 2016. An outbreak may affect over 25% of passengers, and a smaller proportion of crew members.[80]

Human genetics

Epidemiological studies have shown that individuals with different ABO(H) (histo-

saliva glands. The ABH-antigen produced is thought to act as a receptor for human norovirus: A non-functional fucosyltransferase FUT2 provides high protection from the most common norovirus strain, GII.4.[83]

Homozygous carriers of any nonsense mutation in the FUT2 gene are called

non-secretors, as no ABH-antigen is produced. Approximately 20% of Caucasians are non-secretors due to G428A and C571T nonsense mutations in FUT2 and therefore have strong – although not absolute – protection from the norovirus GII.4.[84] Non-secretors can still produce ABH antigens in erythrocytes, as the precursor is formed by FUT1.[81] Some norovirus genotypes (GI.3) can infect non-secretors.[85]

History

The norovirus was originally named the "Norwalk agent" after Norwalk, Ohio, in the United States, where an outbreak of acute gastroenteritis occurred among children at Bronson Elementary School in November 1968. In 1972, electron microscopy on stored human stool samples identified a virus, which was given the name "Norwalk virus". Numerous outbreaks with similar symptoms have been reported since. The cloning and sequencing of the Norwalk virus genome showed that these viruses have a genomic organization consistent with viruses belonging to the family Caliciviridae.[86] The name "norovirus" (Norovirus for the genus) was approved by the International Committee on Taxonomy of Viruses (ICTV) in 2002.[87] In 2011, however, a press release and a newsletter was published by ICTV, which strongly encouraged the media, national health authorities, and the scientific community to use the virus name Norwalk virus, rather than the genus name Norovirus when referring to outbreaks of the disease. This was also a public response by ICTV to the request from an individual in Japan to rename the Norovirus genus because of the possibility of negative associations for people in Japan and elsewhere who have the family name "Noro". Before this position of ICTV was made public, ICTV consulted widely with members of the Caliciviridae Study Group and carefully discussed the case.[88]

In addition to "Norwalk agent" and "Norwalk virus", the virus has also been called "Norwalk-like virus", "small, round-structured viruses" (SRSVs), Spencer flu, and "Snow Mountain virus".[89] Common names of the illness caused by noroviruses still in use include "Roskilde illness", "winter vomiting disease",[90] "winter vomiting bug",[91][92] "viral gastroenteritis", and "acute nonbacterial gastroenteritis".[53]

See also

 

References

  1. ^ a b c "Norovirus (vomiting bug)". nhs.uk. 19 October 2017. Archived from the original on 12 June 2018. Retrieved 8 June 2018.
  2. ^ a b c d e f g h "Norovirus Symptoms". CDC. 24 June 2016. Archived from the original on 6 December 2018. Retrieved 29 December 2017.
  3. ^ from the original on 7 October 2022. Retrieved 5 September 2020.
  4. ^ a b c "Preventing Norovirus Infection". CDC. 5 May 2017. Archived from the original on 9 December 2017. Retrieved 29 December 2017.
  5. ^ a b c d e "Norovirus – Treatment". CDC. Archived from the original on 22 December 2017. Retrieved 29 December 2017.
  6. ^ a b c d e f "Norovirus Worldwide". CDC. 15 December 2017. Archived from the original on 7 December 2018. Retrieved 29 December 2017.
  7. ^ a b "Global Burden of Norovirus and Prospects for Vaccine Development" (PDF). CDC. August 2015. p. 3. Archived (PDF) from the original on 29 December 2017. Retrieved 29 December 2017.
  8. ^ "Norovirus (vomiting bug)". nhs.uk. 19 October 2017. Archived from the original on 12 June 2018. Retrieved 29 May 2021.
  9. PMID 28984764
    .
  10. .
  11. ^ "Norovirus | Clinical Overview | CDC". www.cdc.gov. Archived from the original on 17 March 2016. Retrieved 28 March 2016.
  12. ^
    PMID 23465122
    .
  13. .
  14. .
  15. from the original on 7 October 2022. Retrieved 7 October 2022.
  16. ^ Robert Matthews. "I've lost my appetite..." New Scientist. Archived from the original on 3 May 2015. Retrieved 21 February 2016.
  17. PMID 18826818
    .
  18. .
  19. .
  20. .
  21. .
  22. ^ "Safe Internal Cooking Temperatures Chart". Government of Canada. 7 May 2015. Archived from the original on 27 December 2017. Retrieved 27 December 2017.
  23. ^ "HPA: Shellfish consumption and the risk of norovirus infection". Archived from the original on 14 July 2014. Retrieved 21 February 2016.
  24. from the original on 31 October 2020. Retrieved 5 September 2020.
  25. .
  26. ^ Sherwood, Dave. "How a Chilean raspberry scam dodged food safety controls from China to Canada". Reuters. Archived from the original on 10 October 2020. Retrieved 10 October 2020.
  27. ^ "Cruise ships are seeing the highest number of norovirus outbreaks in a decade". Deseret News. 13 July 2023. Retrieved 15 July 2023.
  28. ^ a b "Family: Caliciviridae | ICTV". www.ictv.global. Archived from the original on 29 August 2021. Retrieved 2 October 2019.
  29. ^ a b Public Health Laboratory Network (25 September 2006). "Norovirus Laboratory Case Definition (LCD)". Australian Government Department of Health and Ageing. Archived from the original on 1 May 2008. Retrieved 15 September 2020.
  30. PMID 31001633
    .
  31. .
  32. .
  33. .
  34. .
  35. ^ .
  36. .
  37. ^ Researchers Discover Primary Sensor That Detects Stomach Viruses Archived 2009-02-02 at the Wayback Machine Newswise, Retrieved on July 20, 2008.
  38. ^ a b c "Viral Zone". ExPASy. Archived from the original on 9 January 2017. Retrieved 15 June 2015.
  39. PMID 11444031
    .
  40. .
  41. .
  42. .
  43. .
  44. .
  45. (PDF) from the original on 29 August 2021. Retrieved 24 June 2019.
  46. .
  47. .
  48. .
  49. .
  50. .
  51. ^ a b "Norovirus: Technical Fact Sheet". National Center for Infectious Diseases, CDC. Archived from the original on 8 March 2012.
  52. PMID 23876403
    .
  53. ^ .
  54. .
  55. .
  56. ^ .
  57. ^ "Diseases Under National Surveillance (as of January 2009)". Public Health Agency of Canada. 17 September 2003. Archived from the original on 23 September 2017. Retrieved 21 November 2017.
  58. ^ Anonymous (1 May 2010). "Notifiable diseases and causative organisms: how to report – GOV.UK". www.gov.uk. Public Health England. Archived from the original on 17 July 2018. Retrieved 26 November 2017.
  59. ^ Anonymous (28 December 2016). "Norovirus | Reporting and Surveillance | CDC". www.cdc.gov. Centers for Disease Control and Prevention. Archived from the original on 9 December 2017. Retrieved 26 November 2017.
  60. PMID 16765204
    .
  61. ^ "List G: EPA Registered Hospital Disinfectants Effective Against Norovirus (Norwalk-like virus)". US Environmental Protection Agency. 28 September 2015. Archived from the original on 15 April 2016. Retrieved 9 May 2016.
  62. ^ "Gastroenteritis and Noroviruses—Dr Jim Grey, Health Protection Agency". The Naked Scientists. 9 December 2007. Archived from the original on 31 March 2014. Retrieved 9 February 2014.
  63. PMID 10833336
    .
  64. ^ HICPAC. "Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, 2011". Healthcare Infection Control Practices Advisory Committee (HICPAC). Centers for Disease Control and Prevention (CDC). Archived from the original on 27 March 2015. Retrieved 19 March 2015.
  65. S2CID 27996748
    .
  66. ^ a b "Norovirus Vaccine" (PDF). Archived (PDF) from the original on 2 October 2008. Retrieved 26 August 2008.
  67. ^ "Takeda to Acquire LigoCyte Pharmaceuticals, Inc". Archived from the original on 29 June 2013. Retrieved 22 June 2013.
  68. PMID 27130672
    .
  69. ^ "Key Products and Pipeline (FY2019 Q2 Pipeline Table)" (PDF). Takeda Pharmaceutical Company. 2019. Archived (PDF) from the original on 6 November 2019. Retrieved 9 December 2019.
  70. ^ "HilleVax Pipeline". Hillevax Pipeline. Archived from the original on 1 October 2021. Retrieved 1 October 2021.
  71. PMID 32878708
    .
  72. ^ "How To Stay Well (When Everyone Else Is Sick)". Webmd.com. Archived from the original on 3 January 2014. Retrieved 28 January 2017.
  73. ^ Frazer J (17 January 2012). "Misery-inducing Norovirus Can Survive for Months—Perhaps Years—in Drinking Water". Scientific American. Archived from the original on 7 March 2012. Retrieved 27 February 2012.
  74. PMID 16473426
    .
  75. .
  76. ^ "Traveler's Diarrhea". Merck Manuals Consumer Version. Archived from the original on 28 February 2015. Retrieved 21 February 2016.
  77. ^ Smith R (24 November 2012). "Winter vomiting bug cases up 40 percent: Health Protection Agency". Telegraph.co.uk. Archived from the original on 24 November 2012. Retrieved 21 February 2016.
  78. ^ from the original on 3 April 2020. Retrieved 24 June 2019.
  79. ^ CDC VSP. "Vessel Sanitation Program – Outbreak Updates for International Cruise Ships". Centers for Disease Control and Prevention. Archived from the original on 10 May 2016. Retrieved 9 May 2016.
  80. ^ "CDC – Vessel Sanitation Program – Balmoral, April 16, 2016". Cdc.gov. Archived from the original on 14 May 2016. Retrieved 9 May 2016.
  81. ^
    PMID 21519121
    .
  82. .
  83. .
  84. .
  85. .
  86. .
  87. ^ ICTVdB Management (2006). 00.012.0.03. Norovirus. In: ICTVdB—The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA
  88. ^ "2011 ICTV Newsletter #9, November 2011". ICTV. 14 November 2011. Archived from the original on 30 July 2012. Retrieved 23 December 2012.
  89. PMID 3036438
    .
  90. from the original on 6 June 2017. Retrieved 10 September 2017.
  91. ^ "Norovirus shuts wards and unit at three Sussex hospitals". BBC News. 11 January 2012. Archived from the original on 15 January 2012. Retrieved 20 January 2012.
  92. ^ "Norovirus at Norfolk hospitals: Disruption continues". BBC News. 12 January 2012. Archived from the original on 20 January 2012. Retrieved 20 January 2012.

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