Approximately 20 million people fall ill every year due to norovirus, according to a new report from the Centers for Disease Control and Prevention, which says the food service industry could do much to decrease that number.

Restaurants and catering services are the most common sources for norovirus outbreaks from contaminated food, according to the report. "Infected food workers are frequently the source of these outbreaks, often by touching ready-to-eat foods served in restaurants with their bare hands," CDC experts wrote.

Norovirus is the most common cause of acute gastroenteritis – often called a stomach bug – in the United States, according to the CDC. Symptoms generally include stomach pain, nausea and diarrhea.

Norovirus particles spread whenever an infected person vomits or defecates. Because swallowing just 18 norovirus particles can sicken a new host, the virus spreads easily, especially when the infected patient is preparing food for a lot of people.

Read - Food poisoning? It was likely a restaurant worker, says CDC

More on food poisoning from CNN Health and all foodborne illness coverage on Eatocracy

Previously:
Unfit for Human Consumption: How nearly 9 million pounds of bad meat escaped into the food supply
What is 'adulterated' meat?
When a slaughterhouse recalled nearly 9 million pounds of meat, this rancher got caught in the crossfire
Who is looking out for your food safety?
Food poisoning: What you need to know