Initially reported as an outbreak of foodborne illness among 30 patrons, WRAL reports tonight that up to 280 people have reported becoming ill after eating at Raleigh’s 42 St. Oyster Bar in late December. Health authorities also believe that illnesses also might not have been linked to oysters as initially reported. As Norovirus is easily transmissible and needs only a few particles to infect, it will be difficult for investigators to pinpoint the initial source. Health authorities tested eight employees for norovirus and all have been negative for the virus.

42nd Street owner Brad Hurley initially thought the culprit was oysters from Louisiana. As a precaution, the restaurant immediately stopped serving the Louisiana oysters and started using only oysters from North Carolina.

Tests of the remaining Louisiana oysters have come back negative, Andre Pierce, Wake County’s environmental health and safety director said.

The restaurant has also worked with the health department to take other precautions, such as eliminating bare hand contact with food and changing from an ammonia sanitizer to chlorine.

Pierce said they may never know the exact source.

“Norovirus is probably one of the most unreported food illnesses out there. It’s hard to detect. It’s hard to find a source. We spend a lot of time and resources trying to track it down. And it is frustrating to us and it is frustrating to the public that you can’t just put a finger on it, but it is very present and I think it’s a lot more out there than we realize.”

Public vomiting is particularly a problem as the act of spewing can cause particles to spread. Norovirus particles can also stay viable on surfaces for weeks. Pathogens can be passed on by someone even if they aren’t feeling ill. In 2008 a foodhandler who did not show symptoms or test positive for Norovirus caused an outbreak leading to over 30 illnesses. It’s believed that the foodhandler, who was caring for ill family members at home, introduced the norovirus into the kitchen by practicing poor personal hygiene.