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Understanding Norovirus: Symptoms, causes, and treatments

Dr. Ajay KohliJan 17, 2024

Global trends suggest that Noroviruses account for nearly 20% of all acute gastroenteritis cases, with an estimated 685 million episodes and 2,12,000 deaths annually. The illness causes inflammation in the stomach and intestines, leading to vomiting, non-bloody diarrhoea, and stomach aches. Transmission is via contaminated food and water as well as from person to person. Treatment of Norovirus infection involves supportive care, although severe dehydration may require hospitalisation with intensive intravenous (through a vein) fluid replacement. Read ahead to know more about Norovirus.




What is Norovirus? 

Noroviruses, also known as "stomach bugs," are related to the diarrhoea-inducing viruses responsible for food-borne illness and long-term morbidity in people of all ages. Infants, older adults, and people with weakened immune systems are particularly prone to Norovirus. 

The virus is notoriously contagious. It can easily and rapidly spread through crowded and enclosed settings like schools, nursing homes, hostels, daycare centres, and restaurants. It is also resistant to severe temperatures and some disinfectants, making its spread difficult to prevent. Several types of Noroviruses exist, though exposure to one does not provide you immunity against others. This means you could get infected more than once in your lifetime. Norovirus can infect people year-round, but it usually peaks during the cold winter months, when chances for person-to-person transmission are more likely.

Hence, many people also refer to this gut virus as the "winter vomiting bug". However, do not confuse Norovirus with flu (influenza), which affects only the respiratory system.

Signs and symptoms of Norovirus

The main complication of Norovirus infection is acute gastroenteritis. When a person first ingests the virus, they may not develop symptoms at once but may feel sick after a day or two. 

Symptoms are usually short-lived (1 to 4 days) and may include one or more of the following.

  • Nausea

  • Projectile Vomiting

  • Diarrhoea

  • Stomach cramps

  • Low-grade fever 

  • Headaches

  • Chills

  • Fatigue

Most symptoms are not serious, but vomiting and diarrhoea can occur suddenly several times a day, leading to dehydration

You might have the following symptoms.

  • Dizziness when standing up

  • Dry mouth

  • Unusual drowsiness

  • Increased thirst

  • Decrease in urination

  • Frustration or sobbing with few or no tears (usually in children)

  • Lethargy

  • Fast heart rate

Some people who are infected with Norovirus may not show symptoms. However, remember that such people are still very contagious and can infect others even before their symptoms start and during the first few days after their symptoms subside. 

What causes the Norovirus infection? 

Norovirus causes food-borne outbreaks, making infected people shed billions of Norovirus particles in their vomit and stool. 

You can get Norovirus illness in the following instances.

  • Come in close contact with an infected person showing symptoms, i.e., by caring for them, shaking hands, and sharing utensils with them.

  • Consume food and beverages that are contaminated with Norovirus by food handlers who have not adequately washed their hands.

  • Accidentally touch surfaces contaminated with vomit droplets, and then put your fingers in your mouth, nose, and eyes.

  • Eat raw fruits and vegetables or shellfish that are irrigated or harvested in contaminated water.

Treatment for Norovirus

In healthy people, Norovirus infection is mostly transient and resolves on its own, so there is no specific treatment. Still, your doctor may prescribe medication to reduce nausea and vomiting while preventing dehydration. You may also be asked to drink plenty of fluids to replace lost fluids. However, in extreme cases of dehydration, it may be necessary to administer fluids intravenously. 

Be careful with the intake of sugary drinks, alcohol, or caffeinated drinks, as they can exacerbate your diarrhoea and dehydration. In children, give oral rehydration solutions containing nutrients and electrolytes to replenish the lost fluids while restoring bowel function.

Diagnosis of Norovirus

Norovirus diagnosis is solely based on your specific symptoms. But your doctor can use a molecular test called real-time reverse transcription polymerase chain reaction to occasionally confirm the infection. 

How can I prevent Norovirus?

Norovirus is a hardy virus that may live on objects and surfaces for days or weeks before it can pass on and trigger illness. However, you can implement the following preventive measures to limit its spread while lowering your chances of getting sick.

  • Wash your hands properly with soap and water after using the toilet, changing diapers, eating, cooking, handling food, or giving yourself or someone else medicine.

  • Wash fruits and vegetables thoroughly.

  • Cook seafood carefully.

  • Clean and disinfect contaminated surfaces immediately with a bleach solution (1000-5000ppm) after vomiting and having diarrhoea.

  • Wear rubber or disposable gloves while handling and washing laundry soiled with vomit or faeces.

  • Keep your hand away from your face to avoid ingesting the virus.

Frequently Asked Questions (FAQs)

Here are some common questions and answers related to the Norovirus.

How long are you contagious after Norovirus?


You are contagious from the time you begin feeling sick until the first few days after you recover. However, in some people, this period can be as long as two weeks after they start to feel better.

When should you go for urgent care?


Seek medical attention immediately if you:

  • vomit blood or have bloody stools

  • show signs of dehydration 

  • have a fever of 102 or higher 

  • have not been able to keep liquids down for 24 hours 

  • experience neurological symptoms like blurred vision or extreme muscle fatigue

Is Norovirus airborne?


When people are infected with Norovirus, they tend to vomit frequently. This causes tiny vomit particles to be sprayed in the air, releasing Norovirus, which can infect others when it lands on surfaces or enters a person's mouth.

Should you be isolated if you have Norovirus?


It is recommended that a person recently infected with Norovirus remain in isolation for 48 hours after their symptoms subside. This is because such individuals at this time are most infectious and can pass on Norovirus or shed the virus onto surfaces and objects.

What should you do if you come in close contact with someone with Norovirus?


While Norovirus spreads easily in environments where people are in close contact, catching it is not inevitable. Therefore, if you have Norovirus: 

  • Stay at home until 2 to 3 days after your symptoms are completely resolved.

  • Drink plenty of fluids to avoid dehydration.

  • Wash your hands thoroughly and frequently with soap and warm water.


Disclaimer: The content on this page is generic and shared only for informational and explanatory purposes. Please consult a doctor before making any health-related decisions.


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