Outbreak 1 – 5 ill: In early August 2015, Public Health Seattle King County (PHSKC) investigated an outbreak of E. coli O157 that occurred among five patrons of Chipotle Mexican Grill located at 1415 Broadway in Seattle, Washington. Illness onset dates occurred on July 28, 2015 (1 case), July 29 (2 cases) and July 31 (2 cases). All five cases reported experiencing diarrhea that turned bloody and abdominal cramps. Two cases reported vomiting. Two cases reported fever. Three cases were hospitalized. Two sought treatment at an emergency department. None of the patients developed HUS. There were no deaths. The Washington Department of Health Public Health Laboratory conducted genetic testing by PFGE on isolates cultured from patients’ specimens. Test results showed that all were infected with an indistinguishable genetic strain assigned PulseNet Identification Numbers EXHX01.0012/EXHA26.1779. This strain had not been seen previously in King County.
Outbreak 2 – 53 ill: Fifty-three people infected with the outbreak strain of STEC O26 have been reported from 9 states. The majority of illnesses have been reported from Washington and Oregon during October 2015. The number of ill people reported from each state is as follows: California (3), Illinois (1), Maryland (1), Minnesota (2), New York (1), Ohio (3), Oregon (13), Pennsylvania (2), and Washington (27).
Illnesses that occurred after November 26, 2015 might not be reported yet due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 3 weeks.
The most recent person reporting Chipotle exposure became ill on November 10, 2015. Reports to PulseNet of new illnesses in this outbreak have slowed substantially since the peak of the outbreak in October 2015. CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill people and to interview them.
Investigators are also using whole genome sequencing (WGS), an advanced laboratory technique, to get more information about the DNA fingerprint of the STEC O26 bacteria causing illness. WGS has been performed on STEC O26 isolates from 29 ill people in Washington (16), California (2), Maryland (1), Minnesota (2), New York (1), Ohio (3), Oregon (3), and Pennsylvania (1). All 29 isolates were highly related genetically to one another. This provides additional evidence that illnesses outside the Pacific Northwest are related to the illnesses in Oregon and Washington.
Outbreak 3 – 5 ill: Additionally, 5 people infected with a different, rare DNA fingerprint of STEC O26 have been identified in Kansas (1), North Dakota (1), and Oklahoma (3) and appear to be linked to Chipotle Mexican Grill. The infections started on dates ranging from November 18, 2015 to November 26, 2015. All five (100%) reported eating at a Chipotle Mexican Grill in the week before illness started. All 3 Oklahoma ill people ate at a single Chipotle location in Oklahoma, and the North Dakota ill person traveled to Kansas during their exposure period and ate at the same Chipotle location as the Kansas ill person.