The ongoing investigation is working to identify which specific ingredient in the chicken salad is linked to illness.
On November 24, 2015 the Montana Public Health Laboratory reported that it tested a sample of celery and onion diced blend produced by Taylor Farms Pacific, Inc. that was collected from a Costco store in Montana and preliminary results indicated the presence of E. coli O157:H7. As a result of the preliminary laboratory results, Taylor Farms Pacific, Inc., voluntarily recalled multiple products containing celery because they may be contaminated with E. coli O157:H7 on November 26, 2015.
However, on December 7, 2015, according to the FDA, further laboratory analysis was unable to confirm the presence of E. coli O157:H7 in a sample of celery and onion diced blend produced by Taylor Farms Pacific, Inc. that was collected from a Costco store in Montana.
As of December 8, 2015, 19 people infected with the outbreak strain of E. coli O157:H7 have been reported from 7 states. No additional illnesses linked to this outbreak have been reported to CDC since November 23. 5 ill people have been hospitalized, and 2 have developed hemolytic uremic syndrome, a type of kidney failure. No deaths have been reported. The epidemiologic evidence available at this time suggests that rotisserie chicken salad made and sold in Costco Wholesale stores in several states is a likely source of this outbreak. 14 (88%) of 16 people purchased or ate rotisserie chicken salad from Costco in the week before illness started.