norovirus 2

138. Watch out for norovirus in winter

Norovirus infection self-diagnosis

1. Vomiting or diarrhea occurs suddenly.
2. Vomiting is the most common symptom in children and diarrhea in adults.
3. I ate undercooked or raw seafood 1-2 days ago.
4. Similar symptoms also appear in people who ate together.
5. In addition to digestive disorders, symptoms such as fever, chills, and muscle pain appear.


If three or more of these apply, norovirus infection may be suspected.



Food poisoning is commonly associated with hot summer months due to prolonged exposure of food to warm and humid conditions, leading to spoilage and potential ingestion of harmful bacteria. However, food poisoning, including norovirus infections, is not confined to specific seasons. It can occur throughout the year, requiring constant vigilance. Especially in autumn and winter, there is a heightened risk of norovirus infection. While awareness is typically high in summer, caution tends to decrease in cooler seasons, leading to an increased incidence of norovirus outbreaks. Norovirus, often transmitted through seafood consumption, becomes a particular concern.



1. What is Norovirus?

Norovirus is a highly contagious virus belonging to the Caliciviridae family. This virus is notorious for causing acute gastroenteritis, leading to symptoms like vomiting, diarrhea, and stomach cramps.


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2. Norovirus Symptoms

Norovirus infection manifests with a range of symptoms, typically appearing within 12 to 48 hours after exposure. Common symptoms include:


  • Nausea: Feeling the urge to vomit is a hallmark symptom of norovirus infection.
  • Vomiting: Sudden and forceful vomiting is a frequent and distinctive symptom.
  • Diarrhea: Watery diarrhea is another common manifestation of norovirus infection.
  • Abdominal Pain: Individuals may experience cramping or discomfort in the abdominal region.
  • Fever: Some cases may present with a mild fever, headache, and muscle aches.

3. Norovirus Causes

Norovirus is primarily transmitted through the fecal-oral route, emphasizing the importance of hygiene and sanitation. Contaminated food, water, surfaces, and person-to-person contact are common modes of transmission. The virus can survive on surfaces for days or even weeks, making it imperative to practice thorough handwashing and disinfection.


4. Norovirus Enteritis Differences

While norovirus primarily affects the gastrointestinal system, it’s essential to understand its distinction from other forms of enteritis. Unlike bacterial or parasitic enteritis, norovirus enteritis is viral in nature. This key difference influences the course of the illness and the appropriate treatment strategies.


5. Foods that Cause Norovirus

Norovirus is notorious for its association with certain types of foods, acting as potential carriers and sources of infection. Understanding these food-related risks is essential for preventing norovirus outbreaks.


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1) Seafood


Raw or Undercooked Seafood: Norovirus can contaminate seafood, especially if it is raw or undercooked. Shellfish, such as oysters, clams, and mussels, pose a higher risk due to their filter-feeding nature. Consuming contaminated raw seafood can lead to norovirus infection.


2) Oysters


Raw or Unprocessed Oysters: Oysters, in particular, have been implicated in numerous norovirus outbreaks. Since oysters are often consumed raw or minimally processed, any contamination in their growing waters can lead to the accumulation of norovirus. Thorough cooking is crucial to eliminate the risk of norovirus transmission.


3) Gwamegi (Dried Pacific Saury)


Traditional Dried Fish: Gwamegi, a traditional Korean dish made from dried Pacific saury, has been associated with norovirus outbreaks. The drying process may not be sufficient to eliminate the virus, especially if the fish has been contaminated during handling or processing. Proper cooking or processing measures are necessary to reduce the risk.


Preventive Measures


To minimize the risk of norovirus transmission through these foods, several preventive measures can be implemented:


  • Thorough Cooking: Cooking seafood, especially shellfish and fish, thoroughly is critical. Heat can destroy the norovirus, making properly cooked seafood safer for consumption.
  • Avoiding Raw Consumption: Refraining from consuming raw or minimally processed seafood, including oysters and certain traditional dishes like Gwamegi, can significantly reduce the risk of norovirus infection.
  • Safe Handling Practices: Implementing strict hygiene practices during the handling and preparation of seafood is crucial. This includes regular handwashing, using sanitized utensils and surfaces, and avoiding cross-contamination.
  • Monitoring Growing Waters: For industries involved in seafood harvesting, regularly monitoring and ensuring the cleanliness of growing waters can mitigate the risk of norovirus contamination.
  • Educating Consumers: Raising awareness among consumers about the risks associated with specific foods and the importance of proper preparation and cooking can contribute to preventing norovirus infections.


6. Seasonal Relationship with Norovirus

Norovirus exhibits a distinct seasonal pattern, with a higher prevalence during the winter months. Understanding this seasonality can aid in implementing preventive measures and enhancing public awareness during peak transmission periods.


7. Norovirus Contagious

Norovirus is highly contagious, with the potential for rapid person-to-person transmission. Infected individuals can shed the virus in their feces and vomit, contaminating their surroundings. Public spaces, shared facilities, and crowded areas pose an increased risk of norovirus transmission, necessitating stringent hygiene practices.


8. Norovirus Treatment

The treatment of norovirus is primarily supportive, focusing on alleviating symptoms and preventing dehydration. Adequate fluid intake is crucial, and oral rehydration solutions are recommended to restore electrolyte balance. In severe cases, hospitalization may be necessary to manage dehydration and complications.


9. Norovirus Treatment Foods

Certain foods can aid in the recovery process during a norovirus infection. Bland, easily digestible foods like rice, bananas, and toast can help soothe the stomach and provide essential nutrients. Hydration remains a cornerstone of treatment, emphasizing the consumption of clear fluids and electrolyte-rich beverages.




10. Foods to Avoid for Norovirus

While certain foods can support recovery, it’s equally important to steer clear of items that may exacerbate symptoms. Fatty, spicy, and dairy-rich foods, as well as caffeine and alcohol, should be avoided during the acute phase of norovirus infection to prevent irritation to the gastrointestinal tract.



In conclusion, norovirus is a formidable adversary, causing widespread gastroenteritis outbreaks and affecting millions globally. Understanding its causes, symptoms, and treatment options is paramount for both prevention and effective management. Practicing good hygiene, especially handwashing, avoiding contaminated foods, and staying informed about seasonal patterns are crucial steps in mitigating the impact of norovirus.



Can I get norovirus from contaminated food?

Yes, norovirus can be transmitted through contaminated food, especially raw or undercooked seafood and oysters.


How long does norovirus survive on surfaces?

Norovirus can survive on surfaces for days or even weeks, emphasizing the importance of thorough disinfection.


Is norovirus more common in certain seasons?

Yes, norovirus is more prevalent in the winter months, contributing to the term “winter vomiting bug.”


Are there medications specifically for norovirus?

Currently, there is no specific antiviral medication for norovirus. Treatment focuses on symptom management and hydration.


Can I go to work with norovirus symptoms?

It is advisable to stay home to prevent spreading the virus to others, as norovirus is highly contagious.


What is the BRAT diet, and does it help with norovirus?

The BRAT diet (bananas, rice, applesauce, toast) can help soothe the stomach during norovirus recovery by providing easily digestible foods.


Is norovirus only transmitted in crowded places?

Norovirus can be transmitted in any setting through contaminated surfaces, food, and person-to-person contact.


Can norovirus be prevented through vaccination?

Currently, there is no specific vaccine for norovirus.


How long does norovirus illness typically last?

Norovirus illness usually lasts one to three days, but symptoms can persist longer in some cases.


Can norovirus cause long-term complications?

While rare, norovirus can lead to complications such as dehydration, especially in vulnerable populations.


Today’s Quiz


Question: What is the recommended diet during norovirus recovery?
a. Spicy foods
b. BRAT diet (bananas, rice, applesauce, toast)
c. Dairy-rich foods
d. Fatty foods

Answer: b. BRAT diet (bananas, rice, applesauce, toast)


Accuracy: 95%.


CDC – Norovirus Overview
Mayo Clinic – Norovirus
National Health Service (NHS) – Norovirus


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