An outbreak of illness due to a rare and virulent strain of E. coli bacteria appears to be the largest of its kind ever reported in the United States, state health officials said Tuesday.
"The complexity of this outbreak and the necessity to be extremely thorough in our investigation means we still have more questions than answers," said state epidemiologist Dr. Kristy Bradley.
Meanwhile, the number of people falling ill from the bacteria continues to rise.
At least 206 people have been sickened by the deadly bacteria, including 149 adults, 53 children and four other people whose ages have not been confirmed. One man died.
Patient ages range between 2 months and 88 years of age, officials said.
State health investigators have interviewed more than 550 people regarding the outbreak so far, with more than 100 people left to interview, said Oklahoma State Department of Health spokeswoman Leslea Bennett-Webb.
Not all of those who were interviewed ate at Country Cottage, the Locust Grove restaurant at the center of the investigation, she said.
And some of those who were interviewed ate at the restaurant but didn't get sick, Bennett-Webb said.
Health officials are not ready to reveal the number of those sickened who ate at the Country Cottage, she said.
"Based on the interviews and new hospitalizations, we haven't seen a large number of secondary infections," she said. Secondary infections refer to those transmitted by person-to-person contact.
"This is very rare, and it's something not normally found here," Bennett-Webb said, noting this strain has never been identified in Oklahoma before.
In addition, water from a private well located on the property of the Country Cottage restaurant was ruled out as a source of the contamination, health officials said.
The Country Cottage restaurant remains the primary focus of investigators.
"We are continuing our efforts to conduct microbiological testing of food preparation and serving surfaces in the restaurant, and we continue to interview cases, as we try to establish an association with those who became ill and a potential source," Bradley said.
Seattle attorney Bill Marler of the Marler Clark law firm has represented thousands of victims of foodborne illness outbreaks since 1993.
"This is highly unusual. We have been involved in every major U.S. outbreak in the last 15 years, and we have only seen this serotype twice before — once traced to apple cider in New York and once connected to water or salad in Texas," he said.
His firm has litigated food poisoning cases against a number of companies, including Wendy's, ConAgra, Chili's, Chi-Chi's and Jack in the Box.
"It may be very difficult to pinpoint a food item as the particular source," Marler told the Tulsa World. "Most folks at buffets eat a little bit of everything or can't recall what they ate, making the identification of a food product tough."
Marler said the parents of a few children who remain hospitalized at St. Francis Hospital have contacted him about possible legal action. Because of the complex nature of the outbreak, Marler said he was not hopeful about their prospects of winning a case.
"If they are not able to figure out what food it was and how it got contaminated, a lot of people will be left uncompensated," he said.
According to Oklahoma State Department of Health records, fewer than 50 cases of E. coli have occurred in Oklahoma each year since 2005.
In 2008, only 18 cases had been reported as of July 31, records show.