Despite headlines full of cruises ruined by rampant food poisoning, a recent investigation has revealed that restaurants are the favored hunting grounds of the bothersome norovirus - which infects about 20 million Americans each year.

According to the US Centers for Disease Control and Prevention (CDC), norovirus gets most of its infamy from high profile cases that infect a large number of people on cruise ships.

However, according to a recent Vital Signs report released by CDC investigators, barely any of the annual norovirus outbreaks that affect 20 million American citizens occur on cruise ships, making up only one percent of National Outbreak Reporting System (NORS). This is even after accounting for outbreaks that occurred on international waters and were reported via collaboration between the cruise industry and the CDC Vessel Sanitation Program.

The large majority of the remaining food poisoning outbreaks, the CDC reports, occurred in licensed eateries on US soil.

"Norovirus outbreaks from contaminated food in restaurants are far too common," CDC Director Tom Frieden said in a statement.  "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."

According to the report, between 2009 and 2012, 1,008 norovirus outbreaks originated from contaminated food served at a restaurant, and 70 percent of those cases originated from an infected food worker.

"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, of the CDC's Division of Viral Diseases.

However, the report details that one in five food service workers have reported working at least once in the previous year while experiencing symptoms of a norovirus infection, such as vomiting or diarrhea.

According to the CDC, this proves that the food service sector needs to implement better rules to ensure the sick don't work, even if that means offering paid sick days and a policy where a sick worker must stay home for at least 48 hours after symptoms have stopped to ensure an infection has passed.

A past Center for Science in the Public Interest (CSPI) Outbreak Alert showed that between 1990 and 2011, nearly double the number of food poisoning outbreaks occurred in restaurants as opposed to homes. The CSPI called for similar food service industry reforms that would ensure the safety of a restaurant's patronage.