Illnesses have been reported from chicken salad purchases at Costco stores in California, Colorado, Missouri, Montana, Utah, Virginia and Washington state. The strain of E. Coli linked to Costco chicken salad that has sickened 19 people in seven states is more likely to be life-threatening than a recent foodborne illness that led to the closure of some Chipotle restaurants in the Northwest People who bought chicken salad at any U.S. Costco store on or before Friday were advised to throw it away, even if no one has gotten sick.