CDC says Chipotle-linked outbreak of E. coli appears over

The Center for Disease Control (CDC) has declared the latest e-coli outbreak at Chipotle Mexican Grill over, two months after the last person fell ill.

The most recent illness reported to the CDC was on December 1, the regulator said on Monday.

The PulseNet database discovered two different, rare DNA fingerprints of Shiga toxin-producing E. coli O26 (STEC O26), and whole genome sequencing (WSG) revealed more detailed information about the DNA of those two bacterial strains. During the second outbreak, five people were infected with one hospitalized.

The two outbreaks were not believed to be related, and the CDC said no specific food has been identified as the cause, though a common meal or ingredient at Chipotle is likely the source.

CDC investigators still don’t know which ingredient carried the foodborne illness, said the agency’s web site.

The criminal probe stems from a norovirus outbreak last summer at a restaurant in Simi Valley, California, where more than 200 workers and customers were sickened. YouGov Brand Index said customer perceptions about Chipotle sank to their lowest level since it began tracking the company in 2007.

Chipotle’s executives have been reassuring customers and investors that steps are being taken to tighten food safety at the popular burrito chain and that they would prevent future food poisoning outbreaks. While multiple food items were collected and tested from Chipotle, CDC officials were unable to verify the presence of any E. coli bacteria in any particular ingredient. The news sparked an increase Monday morning of 5 percent for Chipotle shares. But the outbreak drove the company’s stock down by 26 percent over the past three months and it warned in December of a potentially sizeable hit to profits.

Chipotle reports fourth-quarter earnings after market close on Tuesday. According to Boston College spokesman, 80 students have gotten sick after eating at the fast food chain. The outbreaks affected more than 50 people in 14 states. “Young adults represent the largest share of Chipotle’s overall traffic”, as Bonnie Riggs, a restaurant industry analyst for the NPD Group, which tracks consumer’s awareness about food safety outbreaks, tells CNBC.

The Denver-based Mexican restaurant chain has made significant changes to its food safety procedures, including chopping some vegetables at one central location and blanching onions to kill germs.