Noroviruses are also called
Norwalk-like viruses and caliciviruses. Noroviruses cause gastroenteritis, food infection,
food poisoning, and acute nonbacterial
What causes infection with noroviruses?
typically spread through contaminated water and foods, although they can also
pass from person to person. Water becomes contaminated if human waste enters drinking water because of flooding or from a sewage system that isn't working properly. You may become infected by:
Eating foods or drinking liquids that are
contaminated with norovirus. Shellfish and salad ingredients are the foods most
often infected with the viruses. Food other than shellfish may be contaminated
by food handlers.
Touching surfaces or objects contaminated with
norovirus, and then placing your hand in your mouth.
contact with someone who is infected. For example, if you are a caregiver or
share foods or utensils with someone who is ill, you may become
Persons working in day care centers or nursing homes
should pay special attention to children or residents who have norovirus
illnesses. This virus is very contagious and can spread rapidly throughout
What are the symptoms?
The symptoms of
gastroenteritis caused by the noroviruses include nausea, vomiting, diarrhea,
and abdominal (belly) pain. Diarrhea and vomiting can cause
dehydration. You may have a headache and fever of less
than 100°F (37.8°C). A mild and
brief illness usually develops 24 to 48 hours after you eat or drink the
contaminated food or water and lasts for 24 to 60 hours. Only in rare cases does a person get very sick or have to go to the hospital.
How are infections with noroviruses diagnosed?
Most norovirus infections are mild and pass in a few days. So most people do not
go to their doctors for a diagnosis. You can often diagnosis food
poisoning yourself if others who ate the same food as you also become ill.
If you do go to your doctor, he or she will make the
diagnosis based on your symptoms, a medical history, and a physical exam. Your
doctor will ask where you have been eating and whether anyone who
ate the same foods has the same symptoms. A stool test is sometimes done.
How are infections with noroviruses treated?
treat gastroenteritis caused by noroviruses by managing complications until
Dehydration caused by diarrhea and vomiting is the
most common complication. Do not use medicines, including antibiotics and other
treatments, unless your doctor recommends them.
To prevent dehydration, take
frequent sips of a rehydration drink (such as Pedialyte). Try to drink a cup of water or rehydration drink for each large,
loose stool you have. Soda
and fruit juices have too much sugar and not enough of the important
electrolytes that are lost during diarrhea, and they
should not be used to rehydrate. In cases of severe dehydration, fluids may
need to be replaced through an IV (intravenously).
Try to stay with your normal diet as much as possible. Eating your
usual diet will help you to get enough nutrition. Doctors believe that eating a
normal diet will also help you feel better faster. But try to avoid foods that
are high in fat and sugar. Also avoid spicy foods, alcohol, and coffee for 2
days after all symptoms have disappeared.
How can you prevent infection with noroviruses?
can help prevent infection by doing the following:
Wash your hands before eating or preparing
food. This is especially important if you have just changed any diapers or used
Wash fruits and vegetables and steam oysters before
If you suspect that your drinking water is contaminated, boil water for 1 minute (3 minutes at elevations above 6,500 feet). Then cool and refrigerate it. Water filters will not remove noroviruses.
How this information was developed to help you make better health decisions.