Raleigh, N.C. — Steamed oysters shipped from Louisiana likely caused illness among dozens of people who had eaten at the 42nd St. Oyster Bar in downtown Raleigh, restaurant owner Brad Hurley said Tuesday.

About 40 people have reported getting sick after eating at the popular restaurant on West Jones Street, said Andre Pierce, Wake County's environmental health and safety director. The complaints started on Nov. 30, and the frequency picked up in the past few days.

Public health officials are still investigating the illness outbreak and haven't determined the cause, Pierce said.

Mike Fields and his wife ate steamed oysters at the 42nd St. Oyster Bar a week ago. She didn't get sick, but he did.

"Wednesday evening, I started feeling really bad. All of a sudden, I got so violently ill, we had to go to the emergency room," said Fields, whose eyes were still red from the illness a week later.

"I felt so bad I thought maybe this could be the end," he added.

The county health department and restaurant launched investigations and interviewed patrons.

"The common thread has been that people have eaten steamed oysters, and we've isolated it down to all of those steamed oysters coming out of Louisiana," Hurley said.

After the Louisiana oysters were tied to the illness, the restaurant immediately stopped serving them and started using only oysters from North Carolina, he said.

Pierce said that action is the appropriate response.

"Voluntary segregation of product is certainly appropriate now to alleviate the risk to the public," he said. "That doesn't mean you close the restaurant."

Hurley apologized to customers and said he has never experienced a problem like this before at his restaurant.

"We've never had any issues like this before in the 22 years that we've been doing business," he said. "Nothing that would come close to this."

The restaurant is cooperating fully with the county's investigation, Pierce said.

Health workers are trying to determine what in the oysters caused people to become ill and are evaluating cases and symptoms. Anyone who has eaten at the restaurant in the past two weeks and later felt ill is asked to call the county health department at 919-856-7400.