The Centers for Disease Control and Prevention in Atlanta said each year about 21 million people contract this illness, causing roughly 70,000 to be hospitalized and about 800 die.
Exposure to just 18 viral particles can make a person sick -- infected body fluids contain millions of particles, the CDC said.
Unlike influenza, which is a viral respiratory illness transmitted via the air by an infected person coughing or sneezing and others inhaling the droplets or touching something they landed on such as an elevator button, viral gastroenteritis can be caught by touching an infected surface or from food contaminated by dirty hands.
Norovirus can spread quickly from person to person in crowded, closed places like long-term care facilities, day-care centers, schools, hotels and cruise ships, the CDC said. There is no medication or vaccine to prevent or treat norovirus.
The virus is found in the vomit and stool of infected people and anything they touch if they have not washed their hands well with warm water and soap. It can also be caught when caring for someone with norovirus or sharing foods or eating utensils with them.
People with viral gastroenteritis are contagious from the moment they begin feeling sick until at least three days after they recover, but some people might be contagious for two weeks, the CDC said.
Viral gastroenteritis can also be caught by someone handling, preparing or serving food while sick or still recovering. Wash fruits and vegetables thoroughly before eating them. Do not prepare food while infected, the CDC said.
Clean and disinfect contaminated surfaces by using a bleach-based household cleaner as directed, or make a solution made with 5 tablespoons to 1.5 cups of household bleach per 1 gallon of water, the CDC advised.
Hand sanitizers and hand wipes do not remove the virus, but hand washing for a minimum of 20 seconds will.
It is estimated as many as 30 percent of individuals with Norovirus in their stools are asymptomatic, meaning they do not feel ill, but can spread the disease if they don't wash their hands, health officials said.