Restaurant goers may want to consider the number one cause of food poisoning in the U.S. Officials with the U.S. Centers for Disease Control and Prevention (CDC) announced on Tuesday that most outbreaks involving norovirus contamination of food occur in the food service industry, and the number one cause is handling with bare hands by infected kitchen employees. Kitchen staff often touch ready-to-eat food with their bare hands, according to the report.

“Norovirus outbreaks from contaminated food in restaurants are far too common.” said CDC Director Tom Frieden, M.D., M.P.H.  “All who prepare food, especially the food service industry, can do more to create a work environment that promotes food safety and ensures that workers adhere to food safety laws and regulations that are already in place.”

Norovirus has garnered a lot of attention in recent years as the culprit in cruise ship illness outbreaks. Officials with the CDC found that these outbreaks only account for one percent of all reported norovirus outbreaks. The virus can spread anywhere where food is served and people gather, and it is highly contagious. An estimated 20 million people contract norovirus illnesses each year through contact with infected individuals or contaminated food. Symptoms of norovirus illness include vomiting and diarrhea.

A number of key preventive measures are described in the full report and affirm existing CDC guidelines as well as the Food Code of the Food and Drug Administration. Food workers must practice proper hand washing, use single-use disposable gloves and utensils, and minimize bare-handed contact with food. Kitchen managers and workers should be trained in good safety practices. Policies that require food service employees with illness, especially gastrointestinal, stay home until symptoms disappear should also be established and enforced.

“It is vital that food service workers stay home if they are sick; otherwise, they risk contaminating food that many people will eat,” said Aron Hall, D.V.M., M.S.P.H., of CDC’s Division of Viral Diseases.

More information on norovirus infections is available in Vital Signs published by the CDC.