A norovirus infection is characterized by sudden vomiting and diarrhea. Outbreaks are often seen on cruise ships, in congregate living situations like nursing homes and jails, as well as schools and places where people are close together.

Here are a few things to know about the virus.

Norovirus is the leading cause of foodborne illness in the United States, responsible for 58% of such infections acquired in the country each year, according to the CDC.

Norovirus infections are caused by a group of viruses that spread easily, with as few as 10 viral particles having the ability to make someone sick, health experts say.