Norovirus is the leading cause of outbreaks of diarrhea and vomiting in the US, and it spreads quickly.
Norovirus spreads by contact with an infected person or by touching a contaminated surface or eating contaminated food or drinking contaminated water. Norovirus particles can even float through the air and then settle on surfaces, spreading contamination
Norovirus particles are extremely small and billions of them are in the stool and vomit of infected people.
Any vomit or diarrhea may contain norovirus and should be treated as though it does.
People can transfer norovirus to others for at least three days after being sick.