Norovirus Facts
Making norovirus transmission understandable to those who fear vomiting
(c) 2009 Anna S. Christie & Alvin Bois-Bonifacio
Definitions
Norovirus: The most recent term for all “Norwalk-like viruses”
Stomach flu: Norovirus – actually a misnomer, as these viruses are not and never were influenza or “flu.”
Stomach viruses: Noroviruses
Winter viruses: Noroviruses
Winter vomiting flu: Noroviruses
Gastroenteritis: An illness of the gastro-intestinal tract that involves vomiting and diarrhea – these symptoms may be caused by Noroviruses or by bacteria. Hence, “viral gastroenteritis” or “bacterial gastroenteritis”. Bacterial gastroenteritis is not contagious.
Caliciviruses: Noroviruses (since they belong to the family of calicivirus)
NLVs: Norwalk-like viruses, now called Noroviruses
Virology
Noroviruses (genus Norovirus, family Caliciviridae) are a group of related, single-stranded RNA, non-enveloped viruses that cause acute gastroenteritis in humans. Norovirus was recently approved as the official genus name for the group of viruses provisionally described as "Norwalk-like viruses" (NLV). Currently, human Noroviruses belong to one of three Norovirus genogroups (GI, GII, or GIV), each of which is further divided into >25 genetic clusters.
How it works
Temperature
Noroviruses die at 65 degrees Celsius or 150 degrees Fahrenheit. Cooked food is normally much hotter – up to 100 degrees Celsius. Note that you cannot possibly wash your hands with water this hot (it will scald you) – so there is no need to make the tap run as hot as you can “stand it.” Soap and warm water washes the viral particles down the sink. The virus may survive freezing.
Incubation Period
24-48 hours after ingestion of the virus. Symptoms have been known to appear as early as 12 hours. It all depends on how much you’ve ingested.
When is it contagious?
Once the virus has been ingested and is incubating, it is possible to shed it through stool, without yet showing symptoms. This is one reason why the virus is so highly contagious – people don’t know they have it, yet they spread it to others through poor hygiene (not washing their hands after defecating, then touching others or touching surfaces).
People are contagious for at least 24 hours after the symptoms disappear. There have been virus particles found in the stool samples of people who have been infected some time after this as well, however it is not known whether enough viral particles are secreted in order to infect someone else. (There are too many variables at this point: strength of the virus, number of particles, and strength of others’ immune systems.)
The person who had the virus becomes immune to this year’s particular strain and secretes antibodies with the virus so it isn't contagious anymore to him, even though it is highly contagious to others. This could mean that if your spouse had the virus in October but you didn't, in January he could bring it home and give it to you without ever being sick himself.
Transmission
Norovirus is transmitted through the fecal-oral (feces meaning “stool” and oral meaning “mouth”) route. This means you have to "swallow" the virus particles contained in the feces or vomit of someone who has the virus. “Swallow” means to ingest it into your gastro-intestinal system which is through your mouth. You bite your nails, you lick your fingers, or you contaminate that hotdog bun with your hand and then eat it. It’s also possible that a food-handler with Norovirus touches your food (that isn’t cooked) with dirty hands and then you eat it. This is one form of “food poisoning.” You may contract Norovirus through uncooked shellfish. Raw sewage finds its way into the ocean and into the shellfish – mainly those eaten raw or steamed – oysters, mussels, clams.
When someone vomits outside of a closed-in room (such as a bathroom) the act of vomiting produces a mist or spray that can send airborne particles into the mouths and noses of anyone nearby. As well, vomit particles may land on all surfaces in a bathroom such as flusher handles, taps, counters, even toothbrushes or cups. These are highly contagious. Similarly, diapers and clothing with fecal matter are highly contagious. Cleanup immediately all surfaces with a bleach solution. Wear a mask.
The virus can be active outside a host (person) on surfaces such as counters, toilets, faucets, doorknobs and even clothing. It is unknown exactly how long the virus can live on such surfaces, as this depends on the number of viral particles, temperature, and the nature of the environment. Remember that you cannot catch it by just touching a doorknob. You would have to put your hand into your mouth. Therefore, hand-washing is imperative to prevention of transmission. The main reason for all Norovirus outbreaks is poor hygiene, i.e., people defecating and not washing hands afterward, then contaminating surfaces or foods Note: Alcohol-based hand gels do not kill Norovirus!
Cleanup
The simplest, easiest and cheapest way to kill Norovirus on surfaces is with a chlorine bleach solution of 1 tablespoon of bleach to 1 litre or quart of water. , Never use straight bleach or even half and half bleach and water. A stronger mixture only wastes bleach and destroys the ecosystem – it doesn’t kill the virus any better. I was recently contacted by "Virusafe" about their product "Virusolve" which has been tested and approved in the UK and will hopefully be made available in the USA and Canada soon. Here is a link to their testing page on Norovirus: http://www.virusafe.co.uk/userfiles/Uploads/Files/virus%20tests/VIROSOLVE%20NOROVIRUS-31_12_07.pdf This is their main website: http://www.virusafe.co.uk
Proper Hand washing Technique
Hand washing is the best way to prevent spreading and catching a Norovirus. Hands should be washed in the following way:
What about hand sanitizers?
Study after study has shown that none of these is as effective against the spread of Norovirus as washing your hands with soap and water. In addition, these products are bad for the environment. And you have to check the ingredients. Alcohol-based gels or wipes do not kill Norovirus. Anything marked “antibacterial” but not “antiviral” may not necessarily kill viruses of any kind. The ingredients benzalkonium chloride and benzethonium chloride are effective against Norovirus in concentrations of at least .013%. Many hand sanitizers now contain one of these ingredients.
Myths
It is impossible to get infected by Norovirus in any of these ways:
1. Being “near” someone who has it, including co-workers or friends
2. Being on a plane with people who have it
3. Breathing the same air as someone who has it
4. Being in the same building as someone who has it
5. Walking past a pool of vomit on the floor, road or sidewalk
6. Having sexual relations with an infected person
7. Having a cut in your skin
8. Sitting on a toilet seat, or catching it through your rectum or genitalia
9. Kissing someone who is not yet showing symptoms (Note: it may be possible to catch it from someone who has recently vomited by kissing them, as viral particles may be in their mouth from vomitus. But the virus is not transmitted through saliva.)
10. Sharing cups or utensils with someone who has the virus but isn’t showing symptoms (Note: It’s not recommend that you share drinks or utensils with someone anyway. Many other diseases can be transmitted this way – and some are more serious than Norovirus. However if you have shared a cup or fork with someone, then find out later that they have subsequently developed symptoms of a Norovirus, there is no need to fear.)
Is it airborne?
Norovirus is not airborne in the strictest sense of the word. Some news reports and even family doctors mistakenly report that it is, probably because it’s possible for airborne vomitus droplets to infect others. So if you’re standing near someone who vomits, the airborne “spray” from the vomit splashing will contain millions of viral particles and may infect you as you breathe them in and swallow them. This is not the same thing as a technically “airborne virus”. You cannot catch it from breathing the air of an infected person, going to their home, or working near them.
If your doctor or any other source tells you it is airborne in the sense that one can catch it by only breathing air, please ask them exactly what they mean, how they think the virus is transmitted, a technical/scientific source for their claims and the technical virology in writing that is contrary to what the world-renowned Center for Disease Control reports and claims.
Rotavirus
Rotavirus is a form of Norovirus that children usually get. To make a lot of technical facts quite simple, you don't need to worry about rotaviruses.
Why?
1) Adults will rarely if ever vomit from rotavirus infections. This is because almost all people have had rotavirus by the time they were 5 years old (even mildly, or when they were very young.) There is some form of immunity for adults and they will not be severely affected by these viruses, and
2) You can't prevent the spread of them anyway. It’s just too contagious. Even if children wash their hands frequently, they commonly put their hands in their mouth and they’re not very good at washing up. Children can easily spread this virus.
Vaccine
The Norovirus's genetic profile changes often, meaning the proteins on its outside shell change constantly. Scientists are very close to developing a vaccine for it, and particularly for Rotavirus.
Blood-Type Immunity
There is some good evidence that people with B or AB blood types are immune to noroviruses. By "immune" I mean that the evidence actually points to them being asymptomatic (not having any, or very mild symptoms). [1]
Treatment
Noroviruses are normally quite unpleasant, but not dangerous to otherwise healthy adults. Children may be at risk for dehydration.
If the patient is not vomiting, but has diarrhoea, ensure they are well hydrated at all times.
If the patient is vomiting, it is advisable not to give the patient anything by mouth (even sips of water) unless 2 hours has passed since they vomited.
If vomiting continues despite withholding food & fluids, be on the alert for signs of dehydration, particularly in children. Call your doctor. Take the patient to a hospital emergency room.
Two hours after vomiting stops, begin with very small sips of water every 10 minutes, or give a few ice chips. If the water does not stay down, wait an additional 2 hours. Watch the patient closely for signs of dehydration such as a dry tongue. Go to an ER immediately, especially with a child, if you have any doubt whatsoever they may be dehydrating.
Attempting to drink water immediately after an episode of vomiting inevitably results in bringing back up not only the water, but stomach fluids as well. This is therefore more likely to cause dehydration than prevent it. Again, if there is any doubt that the patient may be becoming dehydrated, take them to a hospital immediately. Dehydration can be fatal.
Once the patient can keep water down, begin administering a fluid that will replace electrolytes such as Pediatlyte (for children) or Gatorade (for adults).
Consult your doctor for treatment if you are concerned. Do not attempt to diagnose and/or treat any illness with information from this website or anywhere on the internet.
Summary
If you don’t put your hands in your mouth, don’t eat uncooked foods prepared in a restaurant, don't stand beside someone who's vomiting and don’t eat raw or steamed shellfish it is impossible to contract a Norovirus. Ensuring that your hands are properly washed before eating ensures that you will not catch it as well. There is no need to fear if you hear that someone at work or a friend you’ve visited has come down with the virus. You can’t catch it by simply being near someone who has it.
No matter how much of an “outbreak” of the virus is in your geographic area, you are at no greater risk of catching it than if only one person has it. Good hygiene will ensure you are safe.
_________________________________________________
Research: Alvin J.V. Bois-Bonifacio
Author: Anna S. Christie
[1] Source: Toronto Mt. Sinai Department of Microbiology
The information on this page, while derived independently, is in accordance with the information from the CDC (Center for Disease Control) in Atlanta.
© 2009 Anna S. Christie
Norovirus: The most recent term for all “Norwalk-like viruses”
Stomach flu: Norovirus – actually a misnomer, as these viruses are not and never were influenza or “flu.”
Stomach viruses: Noroviruses
Winter viruses: Noroviruses
Winter vomiting flu: Noroviruses
Gastroenteritis: An illness of the gastro-intestinal tract that involves vomiting and diarrhea – these symptoms may be caused by Noroviruses or by bacteria. Hence, “viral gastroenteritis” or “bacterial gastroenteritis”. Bacterial gastroenteritis is not contagious.
Caliciviruses: Noroviruses (since they belong to the family of calicivirus)
NLVs: Norwalk-like viruses, now called Noroviruses
Virology
Noroviruses (genus Norovirus, family Caliciviridae) are a group of related, single-stranded RNA, non-enveloped viruses that cause acute gastroenteritis in humans. Norovirus was recently approved as the official genus name for the group of viruses provisionally described as "Norwalk-like viruses" (NLV). Currently, human Noroviruses belong to one of three Norovirus genogroups (GI, GII, or GIV), each of which is further divided into >25 genetic clusters.
How it works
- You ingest (swallow) the virus by viral particles from feces or vomit entering your mouth. The virus incubates for 24-48 hours after ingestion, depending partially on how many viral particles you ingest. Noroviruses are particularly contagious because it only takes a few of them to make you sick.
- In your small intestine, the virus begins to multiply. The lining of your small intestine and/or your stomach will have appropriate attachments for the virus. It attaches itself and releases its genome (bio genes). Those genes shut down the cell and start taking control in order to make more viruses. Your cells are like a factory for the virus replicating.
- Your cells then "explode" or lyse. Then it keeps going to more cells and so on.
- While this is happening your immune response recognizes that cells are dying and T-cells allow your body to mount an immune response against it. They go to B-cells and produce antibodies. The antibodies travel to the small intestine and inactivate the virus.
- The vomiting and even the diarrhea is a secondary response. It's your body's way, evolutionarily, to respond to an infection. It doesn't actually do much to help you - the virus needs to run its course until it's killed off by your immune system. Vomiting once or twice will help you feel better. But there is no need to “get the virus out of there” by vomiting more as it’s not only in your stomach – it’s in your intestinal tract as well.
- The brain may allow you to "not vomit" if you convince it to. While this is not harmful when infected with Norovirus, it can be if you’ve ingested a chemical poison.
Temperature
Noroviruses die at 65 degrees Celsius or 150 degrees Fahrenheit. Cooked food is normally much hotter – up to 100 degrees Celsius. Note that you cannot possibly wash your hands with water this hot (it will scald you) – so there is no need to make the tap run as hot as you can “stand it.” Soap and warm water washes the viral particles down the sink. The virus may survive freezing.
Incubation Period
24-48 hours after ingestion of the virus. Symptoms have been known to appear as early as 12 hours. It all depends on how much you’ve ingested.
When is it contagious?
Once the virus has been ingested and is incubating, it is possible to shed it through stool, without yet showing symptoms. This is one reason why the virus is so highly contagious – people don’t know they have it, yet they spread it to others through poor hygiene (not washing their hands after defecating, then touching others or touching surfaces).
People are contagious for at least 24 hours after the symptoms disappear. There have been virus particles found in the stool samples of people who have been infected some time after this as well, however it is not known whether enough viral particles are secreted in order to infect someone else. (There are too many variables at this point: strength of the virus, number of particles, and strength of others’ immune systems.)
The person who had the virus becomes immune to this year’s particular strain and secretes antibodies with the virus so it isn't contagious anymore to him, even though it is highly contagious to others. This could mean that if your spouse had the virus in October but you didn't, in January he could bring it home and give it to you without ever being sick himself.
Transmission
Norovirus is transmitted through the fecal-oral (feces meaning “stool” and oral meaning “mouth”) route. This means you have to "swallow" the virus particles contained in the feces or vomit of someone who has the virus. “Swallow” means to ingest it into your gastro-intestinal system which is through your mouth. You bite your nails, you lick your fingers, or you contaminate that hotdog bun with your hand and then eat it. It’s also possible that a food-handler with Norovirus touches your food (that isn’t cooked) with dirty hands and then you eat it. This is one form of “food poisoning.” You may contract Norovirus through uncooked shellfish. Raw sewage finds its way into the ocean and into the shellfish – mainly those eaten raw or steamed – oysters, mussels, clams.
When someone vomits outside of a closed-in room (such as a bathroom) the act of vomiting produces a mist or spray that can send airborne particles into the mouths and noses of anyone nearby. As well, vomit particles may land on all surfaces in a bathroom such as flusher handles, taps, counters, even toothbrushes or cups. These are highly contagious. Similarly, diapers and clothing with fecal matter are highly contagious. Cleanup immediately all surfaces with a bleach solution. Wear a mask.
The virus can be active outside a host (person) on surfaces such as counters, toilets, faucets, doorknobs and even clothing. It is unknown exactly how long the virus can live on such surfaces, as this depends on the number of viral particles, temperature, and the nature of the environment. Remember that you cannot catch it by just touching a doorknob. You would have to put your hand into your mouth. Therefore, hand-washing is imperative to prevention of transmission. The main reason for all Norovirus outbreaks is poor hygiene, i.e., people defecating and not washing hands afterward, then contaminating surfaces or foods Note: Alcohol-based hand gels do not kill Norovirus!
Cleanup
The simplest, easiest and cheapest way to kill Norovirus on surfaces is with a chlorine bleach solution of 1 tablespoon of bleach to 1 litre or quart of water. , Never use straight bleach or even half and half bleach and water. A stronger mixture only wastes bleach and destroys the ecosystem – it doesn’t kill the virus any better. I was recently contacted by "Virusafe" about their product "Virusolve" which has been tested and approved in the UK and will hopefully be made available in the USA and Canada soon. Here is a link to their testing page on Norovirus: http://www.virusafe.co.uk/userfiles/Uploads/Files/virus%20tests/VIROSOLVE%20NOROVIRUS-31_12_07.pdf This is their main website: http://www.virusafe.co.uk
Proper Hand washing Technique
Hand washing is the best way to prevent spreading and catching a Norovirus. Hands should be washed in the following way:
- Use warm water, never hot
- Use a mild soap. Antibacterial soap has no effect, as Norovirus is not a bacteria.
- Wash hands for at least 20 seconds (you can sing the ABC song all the way through)
- Rub palms, backs of hands, knuckles to palms, webbing of fingers, thumbs, wrists
- Do not scrub harshly, use harsh soaps or chemicals or extremely hot water – this will destroy your skin leaving more pockets for the viral particles to attach to. Similarly, never wash your hands with bleach or a chemical not meant for hands.
- Rinse well. You are washing the virus down the sink; you are not “killing” it.
- Turn off taps with paper towel, and use paper towel to open doors, and then throw out the paper towel.
- Wash hands after using the rest room, and before eating – about 5 to 10 times a day.
What about hand sanitizers?
Study after study has shown that none of these is as effective against the spread of Norovirus as washing your hands with soap and water. In addition, these products are bad for the environment. And you have to check the ingredients. Alcohol-based gels or wipes do not kill Norovirus. Anything marked “antibacterial” but not “antiviral” may not necessarily kill viruses of any kind. The ingredients benzalkonium chloride and benzethonium chloride are effective against Norovirus in concentrations of at least .013%. Many hand sanitizers now contain one of these ingredients.
Myths
It is impossible to get infected by Norovirus in any of these ways:
1. Being “near” someone who has it, including co-workers or friends
2. Being on a plane with people who have it
3. Breathing the same air as someone who has it
4. Being in the same building as someone who has it
5. Walking past a pool of vomit on the floor, road or sidewalk
6. Having sexual relations with an infected person
7. Having a cut in your skin
8. Sitting on a toilet seat, or catching it through your rectum or genitalia
9. Kissing someone who is not yet showing symptoms (Note: it may be possible to catch it from someone who has recently vomited by kissing them, as viral particles may be in their mouth from vomitus. But the virus is not transmitted through saliva.)
10. Sharing cups or utensils with someone who has the virus but isn’t showing symptoms (Note: It’s not recommend that you share drinks or utensils with someone anyway. Many other diseases can be transmitted this way – and some are more serious than Norovirus. However if you have shared a cup or fork with someone, then find out later that they have subsequently developed symptoms of a Norovirus, there is no need to fear.)
Is it airborne?
Norovirus is not airborne in the strictest sense of the word. Some news reports and even family doctors mistakenly report that it is, probably because it’s possible for airborne vomitus droplets to infect others. So if you’re standing near someone who vomits, the airborne “spray” from the vomit splashing will contain millions of viral particles and may infect you as you breathe them in and swallow them. This is not the same thing as a technically “airborne virus”. You cannot catch it from breathing the air of an infected person, going to their home, or working near them.
If your doctor or any other source tells you it is airborne in the sense that one can catch it by only breathing air, please ask them exactly what they mean, how they think the virus is transmitted, a technical/scientific source for their claims and the technical virology in writing that is contrary to what the world-renowned Center for Disease Control reports and claims.
Rotavirus
Rotavirus is a form of Norovirus that children usually get. To make a lot of technical facts quite simple, you don't need to worry about rotaviruses.
Why?
1) Adults will rarely if ever vomit from rotavirus infections. This is because almost all people have had rotavirus by the time they were 5 years old (even mildly, or when they were very young.) There is some form of immunity for adults and they will not be severely affected by these viruses, and
2) You can't prevent the spread of them anyway. It’s just too contagious. Even if children wash their hands frequently, they commonly put their hands in their mouth and they’re not very good at washing up. Children can easily spread this virus.
Vaccine
The Norovirus's genetic profile changes often, meaning the proteins on its outside shell change constantly. Scientists are very close to developing a vaccine for it, and particularly for Rotavirus.
Blood-Type Immunity
There is some good evidence that people with B or AB blood types are immune to noroviruses. By "immune" I mean that the evidence actually points to them being asymptomatic (not having any, or very mild symptoms). [1]
Treatment
Noroviruses are normally quite unpleasant, but not dangerous to otherwise healthy adults. Children may be at risk for dehydration.
If the patient is not vomiting, but has diarrhoea, ensure they are well hydrated at all times.
If the patient is vomiting, it is advisable not to give the patient anything by mouth (even sips of water) unless 2 hours has passed since they vomited.
If vomiting continues despite withholding food & fluids, be on the alert for signs of dehydration, particularly in children. Call your doctor. Take the patient to a hospital emergency room.
Two hours after vomiting stops, begin with very small sips of water every 10 minutes, or give a few ice chips. If the water does not stay down, wait an additional 2 hours. Watch the patient closely for signs of dehydration such as a dry tongue. Go to an ER immediately, especially with a child, if you have any doubt whatsoever they may be dehydrating.
Attempting to drink water immediately after an episode of vomiting inevitably results in bringing back up not only the water, but stomach fluids as well. This is therefore more likely to cause dehydration than prevent it. Again, if there is any doubt that the patient may be becoming dehydrated, take them to a hospital immediately. Dehydration can be fatal.
Once the patient can keep water down, begin administering a fluid that will replace electrolytes such as Pediatlyte (for children) or Gatorade (for adults).
Consult your doctor for treatment if you are concerned. Do not attempt to diagnose and/or treat any illness with information from this website or anywhere on the internet.
Summary
If you don’t put your hands in your mouth, don’t eat uncooked foods prepared in a restaurant, don't stand beside someone who's vomiting and don’t eat raw or steamed shellfish it is impossible to contract a Norovirus. Ensuring that your hands are properly washed before eating ensures that you will not catch it as well. There is no need to fear if you hear that someone at work or a friend you’ve visited has come down with the virus. You can’t catch it by simply being near someone who has it.
No matter how much of an “outbreak” of the virus is in your geographic area, you are at no greater risk of catching it than if only one person has it. Good hygiene will ensure you are safe.
_________________________________________________
Research: Alvin J.V. Bois-Bonifacio
Author: Anna S. Christie
[1] Source: Toronto Mt. Sinai Department of Microbiology
The information on this page, while derived independently, is in accordance with the information from the CDC (Center for Disease Control) in Atlanta.
© 2009 Anna S. Christie
Norovirus Vaccine
January 2012: For a scholarly article about the research on a norovirus vaccine click here.
February 2010: If you`re up for watching a 40-minute video about it, here it is!
February 2010: If you`re up for watching a 40-minute video about it, here it is!
All material provided on this website is provided for informational or education purposes only. No content is intended to be a substitute for professional medical advice, diagnosis, or treatment. Consult your physician regarding the applicability of any opinions or recommendations with respect to your symptoms or medical condition before making any decision or taking any action. If you are in crisis click here.
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