Many consider cruise ships to be the most common places where norovirus outbreaks occur, but a new analysis from the US Centers for Disease Control and Prevention (CDC) indicates that foodborne outbreaks in restaurants are more frequent, the Center for Infectious Disease Research and Policy at the University of Minnesota reports on its website. The culprits behind restaurant outbreaks are a very contagious pathogen that sick restaurant employees can pass on when preparing food.

A recent report by researcher Vital Signs shows that cruise ships represent just around 1% of all reported outbreaks and that foodborne transmission is the primary mode in 23% of cases, more than half of which can be traced back to restaurants.

The analysis by CDC focuses on the foodborne share of norovirus outbreaks. It is based on data gathered between 2009 and 2012 via the National Outbreak Reporting System (NORS).

A total of 4,318 norovirus outbreaks were reported during that period, of which 1,008 (23%) involved foodborne transmission. This is equal to 48% of the 2,089 foodborne disease outbreaks with a single suspected or confirmed cause during that time. The analysis reveals norovirus is the most common cause of acute gastroenteritis and foodborne disease in the United States.

The article quotes CDC Director Tom Frieden, MD, MPH, who said at a recent media briefing that norovirus needs just a tiny dose to be infectious. The disease can kill up to 800 people a year and accounts for $777 million in annual healthcare costs, according to the CDC study.