COSTELLO: An E. Coli scare causing Chipotle to temporarily close dozens of stores. No one has died in the nearly two dozen cases in Washington State and in Oregon, but the source of contamination is still unknown. Cristina Alesci joins me now with more on this. Oh, this is scary.</s>CRISTINA ALESCI, CNNMONEY CORRESPONDENT: Yes, this is very scary because we don't know the source yet. As with what you would typically expect with these outbreaks, it takes a while for investigators to get to the bottom of it. One thing is for sure, it either came from the meat or the vegetables. And the government does keep track of a deadly strain of E. Coli, and data shows that it is connected to either raw or undercooked ingredients. Now, most restaurants have learned how to cook meat so that you reduce the possibility of contaminated meat getting out. Now, one thing here particular in this case is that Chipotle really prides itself in fresh ingredients, right? You go to the store and you get your tomato, your lettuce, your guacamole, all of that is uncooked. So you increase the likelihood a pathogen is in that, quote/unquote, "fresh ingredient". Which it is fresh -- Chipotle is trying to do the right thing here -- but there is an increased likelihood. Now also keep in mind that the industry has no way of really keeping track of pathogens in our food. It's not like they're testing routinely whether or not these foods contain salmonella, listeria. The only way we find out is after people get sick.</s>COSTELLO: So I would suppose they're interviewing the people who have gotten sick to see if they ate similar items, right? That's the way they track it down.</s>ALESCI: Right, and Chipotle, to your point, is being very cautious, because it's not only shutting down those six stores that are linked to sick patients, but it's taken the precaution of shutting down all the stores in those two states because presumably they're using the same suppliers in those two states, right?
E. Coli Cases Linked to Chipotle.