Norovirus

A Norovirus is a single-stranded positive-sense RNA, non-enveloped Caliciviridae virus.

• Context:
  • It can cause Foodborne Illness.
  • ...
• See: Diarrhea, Dehydration, Hand Washing, Disinfection, Supportive Care, Intravenous Fluids, Gastroenteritis.

---

---

References

2020a

• (Wikipedia, 2020) ⇒ https://en.wikipedia.org/wiki/Norovirus Retrieved:2020-10-14.
  • Norovirus, sometimes referred to as the winter vomiting bug, is the most common cause of gastroenteritis. Infection is characterized by non-bloody diarrhea, vomiting, and stomach pain. Fever or headaches may also occur. Symptoms usually develop 12 to 48 hours after being exposed, and recovery typically occurs within 1 to 3 days. Complications are uncommon, but may include dehydration, especially in the young, the old, and those with other health problems.

    The virus is usually spread by the fecal–oral route. This may be through contaminated food or water or person-to-person contact. It may also spread via contaminated surfaces or through air from the vomit of an infected person. Risk factors include unsanitary food preparation and sharing close quarters. Diagnosis is generally based on symptoms. Confirmatory testing is not usually available but may be performed during outbreaks by public health agencies.

    Prevention involves proper hand washing and disinfection of contaminated surfaces. Alcohol-based hand sanitizers can be used in addition but are less effective than hand washing. There is no vaccine or specific treatment for norovirus. Management involves supportive care such as drinking sufficient fluids or intravenous fluids. Oral rehydration solutions are the preferred fluids to drink, although other drinks without caffeine or alcohol can help.

    Norovirus results in about 685 million cases of disease and 200,000 deaths globally a year. It is common both in the developed and developing world. Those under the age of five are most often affected, and in this group it results in about 50,000 deaths in the developing world. Norovirus infections occur more commonly during winter months. It often occurs in outbreaks, especially among those living in close quarters. In the United States, it is the cause of about half of all foodborne disease outbreaks. The virus is named after the city of Norwalk, Ohio, where an outbreak occurred in 1968.

2020b

• (Wikipedia, 2020) ⇒ https://en.wikipedia.org/wiki/Norovirus#Classification Retrieved:2020-10-14.
  • Noroviruses (NoV) are a genetically diverse group of single-stranded positive-sense RNA, non-enveloped viruses belonging to the family Caliciviridae. According to the International Committee on Taxonomy of Viruses, the genus Norovirus has one species, which is called Norwalk virus.

    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 different genetic clusters or genotypes. 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. Most noroviruses that infect humans belong to genogroups GI and GII. 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. Recent examples include US95/96-US strain, associated with global outbreaks in the mid- to late-1990s; Farmington Hills virus associated with outbreaks in Europe and the United States in 2002 and in 2004; and Hunter virus which was associated with outbreaks in Europe, Japan and Australasia. In 2006, there was another large increase in NoV infection around the globe. Reports have shown a link between the expression of human histo-blood group antigens (HBGAs) and the susceptibility to norovirus infection. Studies have suggested the capsid of noroviruses may have evolved from selective pressure of human HBGAs. HBGAs are not however the receptor or facilitator of norovirus infection. In fact, co-factors such as bile salts may facilitate the infection, making it more intense when introduced during or after the initial infection of the host tissue. 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. The protein MDA-5 may be the primary immune sensor that detects the presence of noroviruses in the body. Some people have common variations of the MDA-5 gene that could make them more susceptible to norovirus infection.

---