What are noroviruses?
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.
- Having direct
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.