Norovirus Infection causes infectious gastroenteritis with symptoms such as severe diarrhea and vomiting. The virus was first discovered in the stool of a patient with acute gastroenteritis that massed out in an elementary school in Norwalk, Ohio, the USA in 1968. It was called “Norwalk virus” after the name of the discovered land. In the 1970s, the development of the electron microscope revealed its form. Since then, it has been named “Norovirus” in 2002. It is a small virus with a diameter of about 1/30,000 mm. It is one of the viruses that need sufficient hygiene management because it is not vulnerable to disinfectants such as alcohol and has strong infectivity.(1)
Is Norovirus Infection A Serious Problem?
The norovirus infection causes acute gastroenteritis in individuals irrespective of age and sex. The incubation period of norovirus is 1 to 2 days. The main symptoms are diarrhea, nausea, vomiting, and other related symptoms, such as abdominal pain, chills, fatigue, fever, myalgia, and sore throat. In general, patients recover in 2 to 3 days, and the progress is relatively good, but in elderly people with weakened resistance, it becomes serious due to dehydration and exhaustion. In rare cases, it can also lead to death due to dehydration.
The virus continues to be excreted in the stool for 1 to 2 weeks after the symptoms are gone and rarely even for a month. Therefore, attention is necessary to prevent secondary infection. There are also cases where no symptoms develop even after infection (obvious infection), and it is necessary to pay attention to the spread of infection from such infected people.(2)(3)
Pathogen Characteristics
Norovirus is a small virus that does not have an envelope (outer coat) covering the outside of the virus. Viruses with such a structure are strong, relatively stable in adverse environments, and may not get neutralized by common disinfectants.
Because norovirus has many genotypes and is easily get mutated, the same person may be infected many times.
Norovirus causes a local infection that only infects and proliferates in epithelial cells of the small intestinal mucosa causing diminished immunity in infected people in a short period of time.
A small number of Norovirus can infect an individual when ingested (ingestion of several tens to 100) and cause infectious gastroenteritis. On the other hand, about 10,000 to 100,000/g of vomit and about 1 billion/g of feces (number of viruses) are included in the vomits and feces of infected people.
Therefore, it can be predicted that infection will spread easily while consuming food and using items contaminated with norovirus and infected people are potential sources of the infection.(4)
Can Norovirus Infection Be Reversed?
There is currently no antiviral agent for norovirus prophylaxis. Treatment for infectious gastroenteritis due to norovirus is clearly symptomatic such as pain relief, antidiarrheal drugs (to stop or limit intestinal movement), administration of rehydrating salts and preparations, infusions when dehydration becomes severe.(5)(6)
Measures Against Infected People
Since norovirus is highly infectious (can easily spread from one person to another), it is necessary to take necessary measures to minimize the spread of infection. When norovirus infection-like symptoms such as diarrhea and vomiting are observed in the patient, it is essential to take the following measures:
Frequent hand washing using correct technique and gargle with warm water (for infected people and those attending them) Norovirus is excreted in feces and vomit and adheres to the skin during defecation, vomiting, and processing. Make sure you wash your hands and gargle so that no virus remains on your skin. Also, use some potent and effective hand sanitizers.
Norovirus Infection Route
The following three routes are known:
- Ingestion of raw oysters and shellfish contaminated with norovirus (improperly cooked)
- If a person infected with norovirus cooks without washing their hands well, the food is contaminated and the food is consumed by non infected individuals.
When a stool or vomit containing norovirus is handled and then fails to wash hands properly to remove the virus (use virus-contaminated hands to ingest food or cook food)
Norovirus can be transmitted through contaminated food or through contact with stool or vomit, – “contact infection”; inhaling droplets from vomit or diarrhea – “splash infection”. This happens when the stool is not properly processed small particles containing the remaining virus will rise up in the air and infect individuals through inhalation.(1)(2)
- Pringle K, Lopman B, Vega E, Vinje J, Parashar UD, Hall AJ. Noroviruses: epidemiology, immunity and prospects for prevention. Future microbiology. 2015;10(1):53-67.
- Teunis P, Sukhrie F, Vennema H, Bogerman J, Beersma M, Koopmans M. Shedding of norovirus in symptomatic and asymptomatic infections. Epidemiology & Infection. 2015;143(8):1710-1717.
- Weinberg GA. Outbreak Epidemiology: One of Many New Frontiers of Norovirus Biology. Oxford University Press US; 2018.
- Grant LR, O’Brien KL, Weatherholtz RC, et al. Norovirus and sapovirus epidemiology and strain characteristics among Navajo and Apache infants. PloS one. 2017;12(1):e0169491.
- Cardemil CV, Parashar UD, Hall AJ. Norovirus infection in older adults: epidemiology, risk factors, and opportunities for prevention and control. Infectious Disease Clinics. 2017;31(4):839-870.
- Hardstaff JL, Clough HE, Lutje V, et al. Foodborne and food-handler norovirus outbreaks: a systematic review. Foodborne pathogens and disease. 2018;15(10):589-597.
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