Norovirus levels are on the rise in the U.S., with nine states in the Northeast dealing with the worst of it, according to the Centers for Disease Control and Prevention. Thirteen percent of norovirus tests there are coming back positive.

“It can cause gastroenteritis, which is an infection of the stomach and the small intestine," said Westchester Medical Center Infectious Disease Specialist Dr. Marina Keller. "And it leads to profuse vomiting for about a day to day and a half.”

In New York, Colgate University has been the site of an outbreak. Madison County health officials said that at least 15 students have symptoms consistent with norovirus. Two students tested positive with an additional 54 suspected cases under investigation. In a statement, Colgate said extra precautions are being taken on campus, including a temporary halt of self-service dining and increased cleaning measures.

Dr. Keller said these locations are most vulnerable to outbreaks.

“In settings where people are pushed together closely and maybe hygiene isn't 100% or it's a foodborne outbreak," she said. "So for instance... just about every year there's a cruise ship or two or even more that has a norovirus outbreak.”

The virus can spread easily through surfaces and eating contaminated food, so the best way to not get sick is to keep your hands clean.

“You go to that wedding buffet and you take food from the table, make sure you wash your hands before you eat," Dr. Keller said. "Make sure you wash your hands after you eat and when you shake hands with other people, touch doorknobs in high-touch areas. Especially when you go to the bathroom, make sure you wash your hands because that's how you're going to get that virus off your hands.”

If you do contract norovirus, Dr. Keller said you should stay away from others so they don't get sick, stay hydrated and to regularly clean areas like the bathroom with bleach.