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

[5] Hand sanitizers based on alcohols tend to be ineffective against noroviruses due to their being non-enveloped, although some virus genotypes are more susceptible.

[10] Norovirus infection is characterized by nausea, vomiting, watery diarrhea, abdominal pain, and in some cases, loss of taste.

[1] Norovirus can establish a long-term infection in people who are immunocompromised, such as those with common variable immunodeficiency or with a suppressed immune system after organ transplantation.

[12] In severe cases, persistent infections can lead to norovirus‐associated enteropathy, intestinal villous atrophy, and malabsorption.

Three days later others started falling ill; 52 people reported a range of symptoms, from fever and nausea to vomiting and diarrhea.

Researchers plotted the seating arrangement: more than 90% of the people at the same table as the sick person later reported becoming ill.

[17] In one outbreak at an international scout jamboree in the Netherlands, each person with gastroenteritis infected an average of 14 people before increased hygiene measures were put in place.

The source of waterborne outbreaks may include water from municipal supplies, wells, recreational lakes, swimming pools, and ice machines.

[24] 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.

[25] Noroviruses (NoV) are a genetically diverse group of single-stranded positive-sense RNA, non-enveloped viruses belonging to the family Caliciviridae.

[29] 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.

[31] Reports have shown a link between the expression of human histo-blood group antigens (HBGAs) and the susceptibility to norovirus infection.

[33] 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 at what specific point in the Norovirus replication cycle bile salts facilitate infection: penetration, uncoating, or maintaining capsid stability.

[49] Sometimes there is loss of taste, general lethargy, weakness, muscle aches, headache, cough, and/or low-grade fever.

The number of deaths from norovirus in the United States is estimated to be around 570–800[50] each year, with most of these occurring in the very young, the elderly, and persons with weakened immune systems.

[52] Tests such as ELISA that use antibodies against a mixture of norovirus strains are available commercially, but lack specificity and sensitivity.

[56][57] Hand washing with soap and water is an effective method for reducing the transmission of norovirus pathogens.

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.

[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.

[74] 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.

Treatments aim to avoid complications by measures such as the management of dehydration caused by fluid loss in vomiting and diarrhea,[5] and to mitigate symptoms using antiemetics and antidiarrheals.

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;[80] there were 12 in 2015, and 10 from 1 January to 9 May 2016.

[81] Epidemiological studies have shown that individuals with different ABO(H) (histo-blood group) phenotypes are infected with NoV strains in a genotype-specific manner.

[82] FUT2 fucosyltransferase transfers a fucose sugar to the end of the ABO(H) precursor in gastrointestinal cells and saliva glands.

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.