SEATTLE (AP) -- Chipotle's industry-leading commitment to tracking its ingredients from farm to table is being put to the test by an E. coli outbreak that has sickened at least 37 people as of Tuesday, nearly all of whom ate recently at one of the chain's restaurants in Washington state or Oregon.
Scientists also said Tuesday that they identified the specific microorganism responsible, which they believe was carried on fresh produce such as lettuce or tomatoes.
The chain of casual Mexican restaurants voluntarily closed 43 locations in the two states after health officials alerted them to a growing number of E. coli cases involving people who shared one common experience: a meal at Chipotle during the last two weeks.
The numbers grew from 3 to 12 probable cases in the Portland area and from 19 to 25 probable cases in five counties near Seattle on Tuesday.
Washington State Epidemiologist Dr. Scott Lindquist said the specific microorganism responsible for the outbreak is Shiga toxin-producing E. coli O26.
Now they're doing more tests, on samples of human waste and on any E. coli found in food samples, looking for any exact DNA matches. That, in turn, should indicate which ingredient carried it into the meals of diners, Lindquist said.
Food from six Chipotle stores linked to the outbreak is being tested, and Lindquist said they may know by Wednesday which produce, if any, tests positive for the same microorganism.
Authorities have already asked Chipotle to turn over information about its food suppliers. "We're really relying on working closely with Chipotle," said Dr. Katrina Hedberg, Oregon's state epidemiologist.
Identifying the supplier of any contaminated produce should be easier in this case than in other outbreaks of food-borne illnesses. Chipotle uses traceability software supplied by a company called FoodLogiQ, based in Durham, North Carolina, and has made a point of promoting its transparency, promising consumers that it can trace every box of fresh ingredients from farm to table, in real time.
"Ideally, any of these trace-back systems should help," said Jaydee Hanson, a senior policy analyst at the Center for Food Safety, a Washington, D.C.-based nonprofit that promotes food safety and sustainable agriculture.
In 2008, health officials initially suspected raw tomatoes to be the source of a salmonella outbreak that sickened people around the country, Hanson recalled. Without adequate ways of tracing tomatoes or other contaminated produce to their origins, everybody stopped buying tomatoes, everywhere.
In this case, Chipotle has been able to have a much more targeted response.
"Being able to quickly find where the problem is, is why our organization and others have been arguing for good traceability, from farm to fork," Hanson said. "Chipotle is to be commended for trying to put in place a system to trace its supply, and hopefully it works this time."
SEATTLE (AP) -- Chipotle closed 43 of its Pacific Northwest locations in response to an E. coli outbreak that health officials have connected to the Mexican food chain.
Thirty-seven people have fallen ill, and most of them had eaten at a Chipotle, officials said Tuesday. Nine people in Washington state and three in Oregon have been hospitalized, but no one has died.
At least one lawsuit has been filed by a woman who says she got sick after eating a burrito bowl at a Chipotle in Vancouver, Washington, on Oct. 21.
Here are some things to know about the outbreak:
WHAT'S BEING DONE TO FIND THE SOURCE?
Health officials in Washington state and Oregon have been interviewing those with a confirmed case of E. coli to find out what they ate. Their blood is being tested to identify the exact strain of the illness.
They have identified the specific microorganism responsible for the E. coli outbreak, which will help officials determine the exact source of the illness, said Dr. Scott Lindquist, Washington state epidemiologist.
Food from the affected Chipotle stores also is being tested. Lindquist says officials may know by Wednesday what type of food tests positive for the same microorganism.
Health officials believe the culprit will likely be fresh food such as lettuce or tomatoes, but they won't know for sure until the testing and interviewing is complete.
COULD PEOPLE GET SICK FROM EATING SOMEWHERE ELSE?
It's possible all the people who have gotten sick have something else in common, other than Chipotle. It's also possible the full extent of the outbreak has not been discovered.
Lindquist says he's keeping an open mind about the reach of the outbreak but is hopeful officials have stopped the spread of the illness by closing Chipotle restaurants in Washington state and the Portland, Oregon, area.
If the illness is traced to a food supplier, the business may be sending its products to other restaurants or grocery stores. Health officials will not know for sure until they find the source of the E. coli.
HAVE OTHER FOOD-BASED HEALTH PROBLEMS BEEN TIED TO CHIPOTLE?
The chain faced a salmonella outbreak linked to tomatoes that sickened dozens of people in Minnesota beginning in August. In California, health workers said norovirus sickened nearly 100 customers and employees at a Chipotle restaurant in Simi Valley in mid-August.
Bill Marler, a Seattle food safety lawyer, says three problems within a couple of months means Chipotle isn't paying enough attention to food safety.
WILL CHIPOTLE BE CLOSING MORE RESTAURANTS?
So far, the outbreak appears limited to Washington state and Oregon. Chipotle says there is no evidence of a link to other locations, so it won't be closing any more restaurants.
The company says it has 1,931 locations, and each restaurant brings in about $2.5 million in revenue a year on average. Chipotle's stock fell 2.5 percent to close at $624 on Monday.
WHAT IS E. COLI AND HOW DO I KNOW IF I HAVE IT?
There are hundreds of E. coli and similar bacteria strains in the intestines of humans. Most are harmless, but a few can cause serious problems.
Symptoms of E. coli infection include diarrhea, abdominal cramps, nausea and vomiting.
Marisa D'Angeli, medical epidemiologist with the Washington State Department of Health, encourages anyone who has been sick with intestinal symptoms and has eaten at Chipotle since mid-October to go to the doctor and get tested.
She also said anyone with bloody diarrhea should go to the doctor whether they have eaten at Chipotle or not.