Norovirus is probably the most common virus that few people have ever heard of.
It is one of the most common causes of gastroenteritis in the United States. While it is notorious for causing outbreaks of diarrhea and vomiting on cruise ships, each year norovirus also causes:
- 21 million cases of gastroenteritis
- 70,000 hospitalizations
- 800 deaths
In 2007, norovirus caused 52% of foodborne illnesses in the United States. In contrast, Salmonella, which gets a lot more attention, only caused about 23% of cases.
If norovirus is so common, how come more people don't know about it?
SymptomsNorovirus symptoms are very similar to other causes of gastroenteritis, including vomiting and watery diarrhea that can lead to dehydration.
Other symptoms might include nausea, stomach cramps, low-grade fever, body aches and fatigue.
People usually get sick about 12 to 48 hours after their exposure to norovirus (incubation period), by direct exposure to someone who is sick, having contact with something that has been contaminated with the virus or by eating contaminated food.
Fortunately, most people recover quickly, getting over the vomiting and diarrhea in just one to three days. Symptoms can last longer - sometimes up to four to six days - in younger children and the elderly, who are the most likely to get extremely ill with norovirus.
Norovirus PreventionThere is no cure for norovirus infections, so that makes it important to try to prevent infections before they happen.
To keep norovirus from spreading when you are sick and to help avoid norovirus infections, it can help to:
- Regularly wash your hands with soap and water
- Wash fruits and vegetables before eating them
- Avoid raw oysters
- Thoroughly disinfect surfaces with a bleach-based household cleaner and wash clothing if they become contaminated after someone throws up or has diarrhea
- Avoid preparing and cooking food for other people until you have been over your norovirus symptoms for at least three days, which is when you shouldn't be contagious anymore
- Avoid swimming in a pool if you have recently had diarrhea
It might also be helpful, as part of healthy swimming habits, to encourage your kids not to swallow any water in a pool.
Some Things to Know About Norovirus
- If you get a norovirus infection, treatment is aimed at staying well hydrated.
- Norovirus is very contagious and is often responsible for outbreaks on cruise ships and in hospitals, nursing homes, restaurants, daycare centers and schools.
- Stool samples can be tested for norovirus, but this is not routinely done by most pediatricians because of the short course of the infection.
- Norovirus was previously called the Norwalk-like virus, because it was first discovered after an outbreak of gastroenteritis in Norwalk, OH, in 1968.
- Like the flu and many other viral infections, people typically don't develop immunity to norovirus and can become infected more than once.
- Most cases of norovirus occur between November and April.
Many people will also be interested to learn that a norovirus vaccine is already being tested. We will have to wait and see when it will become available and if children can have it. Some experts are even suggesting a combined rotavirus and norovirus vaccine to help prevent both common causes of viral gastroenteritis.
CDC. Norovirus: Technical Fact Sheet. http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-factsheet.htm. Accessed Dec 2011.
CDC. Updated Norovirus Outbreak Management and Disease Prevention Guidelines. MMWR. March 4, 2011 / 60(RR03);1-15.
CDC. Surveillance for foodborne disease outbreaks --- United States, 2007. MMWR. 2010;59(31):973–9.