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Norovirus: Facts, Symptoms, Treatment, Prevention 2022 Update

In July 2021, outbreak of very contagious Norovirus was in news. So what is this Norovirus? Norovirus is very commonly known as Winter Vomiting Bug. How fatal the norovirus is? What are the symptoms, treatments, mode of transmission of norovirus?

Are you the one who is currently having diarrhea or vomiting? Maybe you are the one who is not feeling well? Then there is a possibility that you may be suffering from Norovirus (also known as Winter Vomiting Bug)!

We all know about coronavirus, its symptoms, prevention, etc etc. But there is also another virus that is infecting people simultaneously. In fact, UK has recently seen a surge of numbers of Norovirus cases. This article is about that norovirus. Let’s have a look.

What is Norovirus?

Norovirus is a very contagious virus, so anyone can get infected with it. It is so contagious that it has a very high chance to infect anyone. It can infect people of any age. It mainly causes vomiting and diarrhea.

Outbreaks of winter vomiting bug can occur anytime, but most commonly occurs from November to April.

How one can get Norovirus?

Now you may think how you or anyone can get norovirus. We all know we are always exposed to billions of viruses, bacterias, protozoans, etc etc. Each virus, bacteria, or protozoa has a different way to infect us. As norovirus is a virus, it has also a different mode of way to infect us. So how one can get it is very important to know, because if we know its main way of infecting us, only then we will be able to prevent it to make us infected.

Norovirus transmission modes

We can get the winter vomiting bug if

  1. We are in direct contact with a norovirus infected person
  2. We consume norovirus contaminated food or water
  3. We touch norovirus contaminated surface and then if we put our unwashed norovirus contaminated hands into the mouth.

Norovirus Symptoms

Norovirus has the following symptoms

The most common symptoms are –

  1. Diarrhea
  2. Vomiting
  3. Stomach pain
  4. Nausea

Other than the above symptoms there are some other symptoms like

  1. Fever
  2. Body aches
  3. Malaise
  4. Headache
  5. Feeling weak or Fatigue.

This norovirus is a common virus, but it is not related to flu. It can cause vomiting, diarrhea. You will wonder to know that this norovirus is the most common cause of foodborne illness.

So what does winter vomiting bug do inside our body? Once norovirus gets its entry inside our body ( be it through contaminated water or contaminated food or by any means mentioned above), it causes inflammation of our stomach or intestine. So it causes acute gastroenteritis.

Norovirus illness stages

One usually develops symptoms of norovirus 12 to 48 hours after the exposure to norovirus. For most people who get infected with this norovirus, their illness improves within 1 to 3 days. Please consider if one is infected with covid 19 and norovirus simultaneously then situation can get worsen and it requires extra attention.

If one is infected with winter vomiting bug, then there may be extreme illness. One may experience vomiting or diarrhea several times a day. It is alarming. Because diarrhea or vomiting when occurs many times can make a person dehydrated. Chances of getting dehydration are more common in young children, older adults, or people who have other underlying medical conditions.

What are the symptoms of dehydration?  Simple,

  • If you have a decrease in urination
  • If you have dry mouth and throat
  • If you feel dizzy when you are standing up
  • It is important to mention that if your children cry with few or no tears and/ or if your children are unusually sleepy or fussy then it can be due to dehydration. So be careful!

Norovirus Transmission

Winter vomiting bug spreads quickly and easily in different ways. The possible ways of getting the virus are

Contamination through hands

If accidentally you get tiny particles of the virus from poop (feces) or vomit of a norovirus infected person and by any means, these tiny particles of virus enter in your mouth. The virus can enter your mouth if

  • You eat food or drink a liquid that is already contaminated with norovirus
  • You are in direct contact with a norovirus infected person. You can get the virus if you share their food, eating in their utensils. You can also get the virus by caring for them. In simple words, you get the virus if by any means the virus enters your mouth.
  • You touch the surface that is already contaminated with norovirus and then you put the unwashed contaminated fingers in your mouth.

Now, when one is infected with winter vomiting bug, the infected person sheds billions of norovirus particles! You can not see these virus particles through your eyes. With the help of a microscope, you can see it.

So we are unable to see the virus with our normal eye, but you are spreading the virus particle!  You will be surprised to know that only a few virus particles can make people sick.  So think billions of virus particles can infect how many people! Alarming right?

If you are infected with winter vomiting bug then you are contagious. You can spread the virus to others when

  • You have symptoms of norovirus, especially vomiting and diarrhea
  • After you recover from norovirus infection or illness, then during the first few days after recovery.

Studies show that you can spread norovirus even after two weeks or more after you feel better.

Contamination through food and liquid

Norovirus is able to contaminate food and water easily because very few virus particles are needed to make one sick. So you may ask how does food or water gets contaminated with winter vomiting bug. Let’s explain.

  • When an already norovirus infected person touches food or liquid with their bare hands and bare hands have poop ( feces ) or vomit particles. These poop or vomit particles contain the virus as the person is already infected.
  • Food or liquid is placed on a surface or counter where winter vomiting bug contaminated poop or vomit particles are already present.
  • Small drops of vomit from norovirus infected person spray through the air and ultimately land on the food or liquid. The food or liquid is now contaminated with norovirus. So when we eat this contaminated food or drink the contaminated liquid, we can easily get the winter vomiting bug infection.
  • When the food is harvested or grown in the norovirus contaminated water, such as oysters harvested from contaminated water or fruits and vegetables irrigated using winter vomiting bug contaminated water in the field, then the food ( fruits and vegetables) is contaminated. When we consume this food raw, we easily get the norovirus infection.

You will be surprised to know that winter vomiting bug is the leading cause of illness and outbreaks from contaminated food in the United States. The outbreaks mostly occur in food service settings like restaurants.

Already winter vomiting bug infected food workers are many times source of the outbreaks because of touching ready to eat foods with their contaminated hand(s), touching raw vegetables and fruits with bare contaminated hands. It is important to mention that any food that is served raw or handled after being cooked can be contaminated with norovirus through the infected person.

Contamination through water

Norovirus spreads through contaminated water by the following means

  • Drinking water or recreational water can get contaminated with winter vomiting bug. This contaminated water can make you ill because as already mentioned, very few virus particles are needed to make you sick.
  • Water can be contaminated if the septic tank leaks into a well and you drink water from that well.
  • Water can also be contaminated if a norovirus infected person vomits or poops in the water and by any means, this water contaminates your drinking water.
  • Water can be contaminated if it is not treated properly such as with not enough chlorine.

Any other means by which water gets the virus particle can make the water contaminated. We have mentioned above only some common ways the water gets contaminated. In simple words, if the water gets the virus particle only then the water is contaminated.

Transmission through contaminated surfaces

Norovirus spreads through infected people or sick people and contaminated surfaces. Surfaces can become contaminated with winter vomiting bug in several ways, such as when

  • A winter vomiting bug infected person touches the surface with their bare hands contaminated with pop or vomit particles.
  • A winter vomiting bug infected person vomits or has diarrhea that splatters onto surfaces.
  • Any food, liquid, or object that is contaminated with norovirus is placed on the surface.
  • Small particles of vomit spray through the air and then it lands on the surface or it enters in one’s mouth, then he or she swallows it.

Norovirus Prevention

No vaccine is currently available to prevent norovirus. But there are few ways maintaining which you can protect yourself and others from getting infected with winter vomiting bug. The preventive ways are the following

Practice proper hand hygiene

It is very important to wash your hands thoroughly with soap and water. You should do this mainly – after you use the toilet or change diapers, always before preparing food or eating food or handling food, before taking medicine or giving someone medicine in bare hands.

It is important to mention that winter vomiting bug can be present in your vomit or poop (feces) even before you feel sick. Also, the winter vomiting bug can stay in your feces for two weeks or more after your illness improve or you feel better. So continue to wash your hands more frequently particularly during this time period. So chances to spread the virus to others will be less.

You may use alcohol based hand sanitizer additionally, but washing your hands with soap and water is very important. You should not use hand sanitizer alone, because hand sanitizer is not that effective to remove norovirus particles.

But soap and water are effective enough to remove norovirus particles. So additionally you can use alcohol based hand sanitizer, but not as a substitute for soap and water.

Food care and safety

Handle food with care and prepare food safely. Be careful when you are handling fruits and vegetables. Washing your hands with soap and water is not enough, you also need to wash these fruits and vegetables before preparing and eating them. Always cook oysters and other shellfish thoroughly before eating.

Norovirus is relatively resistant to heat. It can survive in temperatures as high as 145 degrees (°F). So quick steaming to cook food is not enough to kill the virus. Because quick steaming that is used for cooking shellfish may not heat food enough that can efficiently kill norovirus. 

If you feel the food may be contaminated with winter vomiting bug, it is better to throw them out.

If your infant and children are sick, keep them out from the area where food is being prepared or handled.

Do not prepare food or care for others when sick

Do not prepare food or handle food or care for others when you are sick and for at least two days after your symptoms stop.

Sick workers in restaurants, schools, daycares, other care facilities, and other places should also follow above mentioned preventive measures otherwise they can spread winter vomiting bug to people. Exposure to winter vomiting bug will give infection and associated illness. So taking preventive measures are always important.

Clean and disinfect surfaces 

Always clean the area immediately after someone vomits or has diarrhea. The cleaning should be thorough and disinfect the entire area. When cleaning the area, put your hands in rubber or disposable gloves, wipe the entire area with a paper towel, then disinfect the area using a bleach based household cleaner.

How to use bleach based household cleaner? Simple, follow the direction of use as mentioned in the product label. Now, leave the disinfectant on the affected area for at least five minutes, if possible leave it for a longer time like 10-12 minutes, then clean the entire area with soap and hot water.

Now, clean the soiled laundry separately, take out the trash and finally wash your hands with soap and water. Always bear in mind, not to contaminate other surface areas. If other areas get contaminated, then you need to clean and disinfect that contaminated area also in the same way mentioned above.

It is better to clean and sanitize kitchen utensils, counters and surfaces routinely before preparing food. Then the food will be safe from norovirus. 

You can use a chlorine bleach solution with a concentration of 1000 to 5000 ppm ( 5 to 25 tablespoons of household bleach 5 percent to 8 percent per gallon of water).

Thoroughly wash laundry

Immediately remove the norovirus contaminated clothes or linens ( be it through vomit or feces) and wash them.

Just remember few things

  1. Handle the soiled items carefully without agitating them.
  2. Always wear rubber or disposable gloves when you are handling soiled items and after that wash your hands carefully with soap and water.
  3. Wash the soiled items with detergent and hot water at the maximum available cycle length of the washing machine and then machine dry them at the highest heat setting if possible. Do not mix these soiled items with other laundry items. Always wash norovirus contaminated cloth separately.

Norovirus Diagnosis

Norovirus test samples

Norovirus can be diagnosed by some body sample testing. Winter vomiting bug testing can be done through – whole stool or stool specimen or vomitus sample.

Stool specimens should be collected during the acute phase of illness( up to 72 hours after symptoms start) while the stool is still liquid or semisolid. Because the greatest amount of virus particles are shed during this acute phase of illness.

Vomitus can also be collected in addition.

Laboratory diagnosis

Detection of winter vomiting bug can be done by detecting viral RNA which is the genetic material of the virus. Mostly reverse transcription real time polymerase chain reaction assays ( RT-qPCR) are used to detect norovirus.

RT-qPCR assays are preferred because they can detect as few as 10 to 100 norovirus copies. This assay also provides estimates of viral load.

Norovirus Treatment

  • No specific medicine is available to treat winter vomiting bug infection.
  • As this is a viral infection, no medicine is there to treat the illness.  The illness usually goes away within a few days. 
  • Drink plenty of liquids to avoid dehydration as the fluid is lost due to vomiting and diarrhea. Drinking plenty of liquids replaces the lost fluid in our body. So it will help to prevent dehydration.
  • Sports drinks and other drinks without caffeine or alcohol can be helpful in mild dehydration. But these drinks lack important nutrients and minerals. So oral dehydration fluids that one can get over the counter are most helpful.
  • Dehydration can be fatal. It can give serious problems. So the main motto should be to prevent dehydration by drinking lots of fluid. Because if severe dehydration occurs, then hospitalization may be required to give fluids through the vein (intravenous fluids or IV fluids)
  • Be careful with your infant or child who is sick due to norovirus. Monitor for signs of dehydration. Infant or children who are dehydrated may cry with few or no tears, the tongue will be dry, be unusually sleepy or fussy.
  • Always seek medical help if you think you or someone is dehydrated. Never ignore dehydration.
  • Taking adequate rest is really important.

It is important to note that antibiotic drugs never help to treat winter vomiting bug illness because antibiotic drugs fight against bacteria, not against viruses. So as norovirus infection is a viral infection, so you will not get any benefit from taking antibiotics.

Final words:

In general norovirus is not life threatening, the reason behind the winter vomiting bug deaths are related to extreme dehydration! The only concern is the dehydration due to norovirus. It is just that winter vomiting bug makes the patient extremely weak. So if one already had a weakness before norovirus infection, then some extra precaution is needed. Certainly for the same reason, corona virus patients need more attention.

Also, after covid recovery (post covid period) people becomes weak in general, so norovirus infection could be more complicated in such cases, a little more precaution can prevent it. If one gets winter vomiting bug, do not panic. Take rest and maintain all the above measures, it will cure automatically. Stay healthy and happy.


  1. Harrison’s Principles of Internal Medicine 20th edition, ( page 254 to 262, page 1028, page 1035, page 1463 to 1465 )
  2. NHS, UK
  3. WHO

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