Epidemiology, Infectious Diseases, Microbiology, Viruses

Norovirus, the Stomach Bug: Not Just for Cruise Ships. All You Need to Know.

Author Chandana Balasubramanian , 14-Nov-2023

Norovirus, commonly known as the stomach bug, has long been associated with outbreaks on cruise ships. However, its impact extends far beyond the high seas. This highly contagious virus is a leading cause of gastroenteritis worldwide and affects people of all ages and in various settings. It is responsible for nearly half of all gastroenteritis cases worldwide. 


Understanding the ins and outs of norovirus is crucial to reduce the risk of getting infected and minimize its disruptive effects on public health. In this guide, we delve into all you need to know about norovirus, including the history, epidemiology, transmission, symptoms, diagnosis, treatment, and preventive methods.



Norovirus was originally called the ‘Norwalk virus’ or ‘Norwalk agent’ after the town of Norwalk, Ohio, where it was first identified. The virus was first discovered by Dr. Albert Kapikian and his colleagues in 1972 after an outbreak of gastroenteritis at a school in Norwalk in 1968. 



Norovirus is prevalent worldwide and affects people of all ages. According to the World Health Organization (WHO), the virus is responsible for an estimated 685 million cases of gastroenteritis annually. 200 million of these cases are in children under five. 

Norovirus causes 200,000 deaths each year with 50,000 of them being in children under five. 

Norovirus outbreaks

Notable and recent norovirus outbreaks include:

Cruise ships

  • 1,939 people were infected with norovirus on cruise ships in 2023.
  • Norovirus cruise ship outbreaks peaked in 2023 with 13 outbreaks reported, the highest in over a decade.
  • In June 2023, 110 passengers and 8 crew members fell ill aboard a Vikings Cruises ship.
  • Over 175 people got a norovirus infection on a Celebrity Cruises ship in May, 2023.
  • One of the biggest norovirus outbreaks on a cruise was in 2014, when almost 700 people were infected. The ship was the Royal Caribbean Explorer of the Seas. 
  • In 2019, 561 people were infected with norovirus aboard the Royal Caribbean Oasis of the Sea cruise line. 



  • US CDC reports that norovirus cases are on the rise in 2023. 
  • Between August 1 to October 9, 2023, 100 norovirus outbreaks were reported (CDC NoroSTAT data).



  • UK Health Security Agency (UKHSA) data shows that the majority of norovirus cases in the UK are in care home settings. 
  • The agency reports that outbreaks in educational settings have also increased, returning to pre-pandemic levels. 
  • Most-reported cases are in people over 65 years of age.


GIDEON offers more information about norovirus outbreaks and infectious disease outbreak maps.


How is it spread?

Norovirus outbreaks are common in closed and crowded environments, such as hospitals, nursing homes, daycare centers, and cruise ships. The virus tends to spread quickly in these settings because of close contact between people. 

While the infection is often in the news in relation to cruise ships, the US CDC reports that healthcare facilities, including long-term care facilities and hospitals, are the most common places to catch a norovirus infection.   

Norovirus spreads rapidly and efficiently, making it highly contagious. It primarily spreads through the fecal-oral route, either by consuming contaminated food or water or by direct contact with an infected person.

The virus can also spread through airborne particles when an infected person vomits. It’s important to note that norovirus is incredibly resilient and can survive on surfaces and objects for a significant period, contributing to its rapid transmission.

Norovirus can be transmitted all year round but cases do peak in winters, which is why the infection is also known as the ‘winter vomiting disease’ or ‘winter vomiting bug.’ 


Biology of the disease
Norovirus illustration

Image: Norovirus illustration


Norovirus belongs to the Caliciviridae family of viruses. 

Once ingested, the human norovirus (HNoV) starts to replicate in the small intestine. It then triggers an immune response, causing inflammation in the stomach and intestines. 

This inflammation leads to the symptoms associated with norovirus infection, such as vomiting and diarrhea, which are common symptoms of norovirus infection.



Typically, norovirus symptoms appear within 1-2 days after exposure to the virus.

Norovirus symptoms include:

  • Nausea
  • Vomiting
  • Diarrhea, and 
  • Abdominal cramps. 


Some people may also experience a high fever, muscle aches, and fatigue. 

In most cases, a norovirus infection is typically self-limiting (which means it clears up on its own in a few days). 



Diagnosis of norovirus is primarily based on the patient’s symptoms and clinical history. 

Laboratory tests, including stool, vomit, or food samples, can be used to confirm a norovirus diagnosis. However, these tests are not typically done unless there’s an outbreak or severe illness related to norovirus.



There’s no specific antiviral medication to treat norovirus. The main goal of treatment is to prevent dehydration by replacing lost fluids and electrolytes. Over-the-counter rehydration solutions are generally recommended. 

If the infected person has a fever, a healthcare provider may recommend paracetamol. 

In severe cases, hospitalization may be required for intravenous fluid administration to manage the symptoms of norovirus.

Please note: this information is for educational purposes only. It cannot be used to diagnose or treat an infection. If you or a loved one may be sick, please consult a licensed healthcare professional for advice. 



Preventing a norovirus infection involves practicing good hygiene. 

This includes:

  • Frequent handwashing with soap and hot water, especially before handling food and after using the toilet. 
  • Disinfecting contaminated surfaces using bleach
  • Washing fruits and vegetables thoroughly, and 
  • Cooking seafood properly, particularly shellfish. 


Additionally, people infected with norovirus should avoid preparing food for others until at least three days after they have recovered.


FAQs about Norovirus

Is stomach flu contagious?

Yes, the stomach flu (or norovirus) is highly contagious and spreads easily from person to person.

Norovirus incubation period: How long does norovirus last?

The incubation period of norovirus (the time between exposure to the virus and the onset of symptoms) usually ranges between 1-2 days.

However, an infected person can start spreading the virus even before they start showing symptoms. Plus, they can continue to shed the virus for up to two weeks after recovery, contributing to the contagious nature of the virus.

Norovirus vaccine: Is there a vaccine for the stomach flu?

Currently, there’s no approved vaccine for norovirus. However, several vaccines are in the development and testing stages. The biggest challenge for vaccine development is that there are over 35 different Norovirus types, making it difficult for one vaccine to conquer them all.

Does the flu vaccine protect against the stomach flu?

No, the flu vaccine does not prevent a norovirus infection. This is because the two infections are caused by different viruses. 

Norovirus infections are not a type of flu, they are just commonly called the stomach ‘flu.’ The flu shot, on the other hand, protects against the influenza virus. 

Rotavirus vs. Norovirus: What are the differences?

The stomach flu or viral gastroenteritis can be caused by different types of viruses, primarily the norovirus and rotavirus. The two viral infections cannot be identified based on symptoms alone; lab tests are needed.

The main differences between rotavirus and norovirus are:

  • Rotavirus is a double-stranded RNA virus that looks like a wheel under an electron microscope. Norovirus is a single-stranded RNA virus that is non-enveloped. 
  • Rotavirus belongs to the Reoviridae family of viruses while norovirus belongs to Caliciviridae. 
  • Rotavirus is more common in children and norovirus trends to affect adults more.
  • There is a rotavirus vaccine but no norovirus vaccine exists.




Norovirus is a highly contagious virus that causes gastroenteritis. While there’s no specific treatment or vaccine currently available, good hygiene can significantly reduce the risk of infection, particularly handwashing. 

Understanding the various aspects of norovirus, including its symptoms, diagnosis, and treatment, can help in managing and preventing this illness. Since the virus is highly contagious, reporting infections to a public health agency early can help prevent widespread norovirus outbreaks.


The GIDEON difference

GIDEON is one of the most well-known and comprehensive global databases for infectious diseases. Data is refreshed daily, and the GIDEON API allows medical professionals and researchers access to a continuous stream of data. Whether your research involves quantifying data, learning about specific microbes, or testing out differential diagnosis tools– GIDEON has you covered with a program that has met standards for accessibility excellence.

Learn more about Norovirus and gastroenteritis on the GIDEON platform.


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Chandana Balasubramanian

Chandana Balasubramanian is an experienced healthcare executive who writes on the intersection of healthcare and technology. She is the President of Global Insight Advisory Network, and has a Masters degree in Biomedical Engineering from the University of Wisconsin-Madison, USA.

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