(Bloomberg) — Chipotle Mexican Grill Inc., still reeling fromrecent outbreaks of E. coli and norovirus at its restaurants, isnow being investigated for its link to a new spate of illnesses inthree additional states.

Five people in Kansas, North Dakota and Oklahoma have fallen illfrom an E. coli strain with a rare DNA fingerprint, the U.S.Centers for Disease Control and Prevention said Monday in astatement. All five, who became sick on dates ranging from Nov. 18to Nov. 26, reported eating at a Chipotle in the week before theirillnesses started.

The new report may further damage Chipotle’s reputation, whichhas been battered in recent weeks by an outbreak of E. coli thatafflicted at least 53 people in nine states. That was followed by anorovirus contagion at a Boston location that sickened more than140 college students. The company has estimated that sales willfall as much as 11 percent in the fourth quarter as the illnessesbring attention to the company’s food-safety struggles.

“Since this issue began, we have completed a comprehensivereassessment of our food safety programs with an eye to findingbest practices for each of the ingredients we use,” Chris Arnold, aChipotle spokesman, said today in an e-mailed statement. “We arenow in the process of implementing those programs.”

Chipotle’s shares slumped as much as 4.6 percent to $498.20Tuesday in New York. The Denver-based company had dropped 24percent this year through Monday’s close, pulled lower primarily bythe food-safety issues.

Illnesses connected?

Chipotle said the three most recently reported illnesses allstemmed from two restaurants: one in Oklahoma and one in Kansas.Arnold added that the company thinks the illnesses are connected tothe larger, previously reported outbreak.

“We believe they are related, and are working with the CDC andFDA while they investigate,” Arnold said.

The CDC released information about the new illnesses as part ofan update on the wider outbreak. The agency said it was“investigating another, more recent outbreak of a different, rareDNA fingerprint Shiga toxin producing E. coli” linked toChipotle.

“Because it is not known if these infections are related to thelarger, previously reported outbreak, these illnesses are not beingincluded in the case count for that outbreak,” the CDC said.

New procedures

After Chipotle was linked to the E. coli contagion in October,it temporarily shut down locations in Washington state and Oregon.The restaurant chain hired IEH Laboratories & Consulting Groupto help refine its procedures. The company has revamped its supplychain and is conducting DNA testing of produce in an effort to keepfood safe. The cause of the E. coli contagion still hasn’t beenfound.

Mansour Samadpour, head of IEH Laboratories, said after therestaurants reopened that the new procedures made Chipotle anindustry leader.

“While it is never possible to completely eliminate all risk,this program eliminates or mitigates risk to a level near zero,” hesaid earlier this month.

— With assistance from Leslie Patton.

Related: Chipotle shuts restaurant after college studentsget sick

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