Trigger Warning: This blog may be very triggering to people with emetophobia, as vomiting is discussed in plain-speak. My hope is that it will reassure some emetophobic people so they can live a more normal life.
Norovirus is the scientific term for what has commonly been called “stomach flu,” “stomach bug,” “winter vomiting virus” and a few other terms. It’s short for “Norwalk-like viruses,” but it is neither a flu nor a bug. Norovirus causes several hours of nausea, vomiting and diarrhea. One may also have body aches, fatigue and a fever for up to 24 hours. All in all, it’s not very nice to have and nobody likes it. However in the grand scheme of things it’s harmless and over with quickly. The only thing you have to watch out for is that a child doesn’t get dehydrated, which can happen quickly and can be fatal if not attended to. Kids need to just have a few ice chips or a teaspoon of water and wait to see if they can keep it down. If not, keep trying and watch for signs of dehydration – they may need to go to a hospital for IV fluids. Adults can also get dehydrated. Sip water very very slowly and hold off on any water until you haven’t had vomiting for a couple of hours.
How contagious is Norovirus? Well, compared to Covid-19 which is airborne and you can catch by just breathing near a contagious person, it doesn’t seem so bad. Norovirus particles (virions) must be ingested (swallowed) in order to get you sick. This means that normally they enter through the mouth but sometimes the nose, and are sniffed back and swallowed. It is unlikely to ever get Norovirus through your eyes although it is theoretically possible (but your finger would have to be filthy). Sometimes Norovirus swirls through the air either when someone vomits in a room, or you flush a toilet without the lid being down. (I know, gross, eh?) You can pick up Norovirus particles on your hands when they settle on counters or doorknobs or a person with literally poop or vomit on their hand touches a knob or counter and then you touch it later and put your hand in your mouth. The particles stay active for about 9 days on surfaces that have not been cleaned, but just to be safe it’s good to think of surfaces as possibly contaminated for 14 days. Norovirus is present in saliva, but scientists don’t think it’s enough to make someone else sick through kissing or sharing utensils/cups – unless the sick person has just vomited and not washed out their mouth. You cannot catch Norovirus by having sex, or through the bloodstream, or on a toilet seat, or by sitting on an airplane and definitely not by breathing the air near a sick person. Unfortunately one of the ways people catch Norovirus is through food that has been handled by a sick worker (who hasn’t washed their hands) and the food is not cooked fully.
Norovirus is killed at 65C or 150F. This is a little hotter than food is normally kept in a restaurant (60C is all that’s required) and for water, too hot to put your hand in. However it is nowhere near boiling (100C or 212F). Check the manual of your washing machine and dryer to see how hot they get on their hot cycles. If it isn’t high enough, you’ll have to add bleach to the wash to kill off the Norovirus on your laundry. Diluted bleach is cheap and easy to find, and perfect for cleaning up if someone in your house is sick. Google how much bleach you need for porous surfaces, non-porous, laundry, etc. There’s lots of great info out there but don’t go crazy by using straight bleach or way too much bleach. You can literally make people sick doing that. Carpets must be cleaned with a steam-cleaner as you can’t bleach them. Keep contaminated sheets, clothing and underwear of sick people separate from other laundry for 2 weeks.
Washing hands with plain soap and water is the best way to get rid of Norovirus on your hands. You don’t need to scrub or go crazy – just 20 seconds washing all the areas of hands and wrists, then rinse off. Hand sanitizers are not as effective as plain soap and water. Some hand sanitizers don’t kill Norovirus (eg. alcohol-based). If you find one that has benzalkonium chloride, that will work but you have to leave it on for a minute or two. Again, Google will tell you if your hand sanitizer works for Norovirus.
One of the more common ways to catch Norovirus is through food, unfortunately. In fact, 70% of “food poisoning” is actually Norovirus and there was nothing wrong with the food. If you’re worried about your restaurant food, order takeout and microwave it to above 65C (use a food thermometer so you don’t go crazy and burn the food). Skip the salads.
Wearing a mask is a great way to prevent not only Covid-19 but Norovirus as well. They work because they keep your hands away from your mouth and nose. You can’t breathe Norovirus in, remember, but that mask will remind you not to touch your mouth or nose unless you’ve washed your hands. This method works great for kids as well.
The incubation period for Norovirus is 24-48 hours. Depending on how much viral load you’ve ingested, you will get sick either sooner or later. Some folks have even become ill before 24 hours. Norovirus has a “sudden onset” of symptoms. This means that you could feel increasing nausea for about an hour, maybe two, during which time you may have diarrhea that is like water (simply having soft stool is not indicative of Norovirus). Sudden onset does not mean that you’re fine one minute and vomiting the next. You’ll have plenty time to figure it out, get home from work, etc.
People are contagious from the time they begin to get sick until about 2 weeks after. They’re only contagious after because the Norovirus is shed in their stool. So if you trust someone to wash their hands after using the bathroom, then they’re not contagious at all. You can visit someone’s house if they’ve just gotten over Norovirus. Just don’t put your hands in your mouth or nose until you get home and wash them. Kids aren’t great at wiping bums or washing hands, so kids do carry a lot of Norovirus around and it spreads in schools. Many people in nursing homes are in diapers, and staff don’t use full PPE when changing diapers so they can easily spread the virus to others in the nursing home. Perhaps now that PPE is required for Covid, we will see less spread of Norovirus in nursing homes. That would be great.
It’s also great that people are wearing masks AND washing hands a lot more, and a lot more thoroughly. Scientists are also working on a Norovirus vaccine, which has proven tricky because the virus mutates during the year and so far would require 1 or 2 boosters every season. I know people with emetophobia would jump at that, but most people wouldn’t and vaccines like everything else have to be economical and practical.
You cannot catch Norovirus from your cat, nor can you give it to your cat. Dogs can carry it only if they’ve come into contact with the vomit or feces of an infected person. Oysters may contain Norovirus and if you eat them raw, you’re rolling the dice. You cannot get Norovirus from tap water.
For more tips, myths, information and cleaning solutions, check the websites below.
- Burrell, Christopher J et al. Caliciviruses, in Fenner and White’s Medical Virology (Fifth Edition), 2017
- Cates, J.E., Vinjé, J., Parashar, U., Hall, A.J., 2020. Recent advances in human norovirus
- research and implications for candidate vaccines. Expert Rev. Vaccines 0, 1–10.
Centers for Disease Control and Prevention
de Graaf, M., van Beek, J., Koopmans, M.P.G., 2016. Human norovirus transmission and
evolution in a changing world. Nat. Rev. Microbiol. 14, 421–433.
Estes, M.K., Ettayebi, K., Tenge, V.R., Murakami, K., Karandikar, U., Lin, S.-C., Ayyar,
B.V., Cortes-Penfield, N.W., Haga, K., Neill, F.H., Opekun, A.R., Broughman, J.R.,
Zeng, X.-L., Blutt, S.E., Crawford, S.E., Ramani, S., Graham, D.Y., Atmar, R.L., 2019.
Human Norovirus cultivation in nontransformed stem cell-derived human intestinal
enteroid cultures: success and challenges. Viruses 11, 638.
Foodborne Disease Burden Epidemiology Reference Group. 2015. WHO estimates of the global burden of foodborne diseases. World Health Organization – World Health Organization, Geneva, Switzerland, 2019
- Garza, Jose M., Cohen, Mitchell, B. Infectious Diarrhea, in Pediatric Gastrointestinal and Liver Disease (Fourth Edition), 2011
Green, K. Y., Noroviruses and Sapovirus, in Encyclopedia of Virology (Third Edition), 2008
Yates, Marylynn, Norovirus, in Microbiology of Waterborne Diseases (Second Edition), 2014