Multistate Outbreaks of Shiga toxin-producing Escherichia coli O26 Infections Linked to Chipotle Mexican Grill Restaurants (Final Update)
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Posted February 1, 2016 12:00 PM ET
These two outbreaks appear to be over. However, E. coli is still an important cause of human illness in the United States. More information about E. coli, and steps people can take to reduce their risk of infection, can be found on the CDC E. coli web page.
Highlights
- Read the Advice to Food Industries & Consumers »
- These two outbreaks appear to be over. The most recent illness reported to CDC started on December 1, 2015.
- CDC, the U.S. Food and Drug Administration, the U.S. Department of Agriculture's Food Safety and Inspection Service, and public health officials in several states investigated two separate outbreaks of Shiga toxin-producing Escherichia coli O26 (STEC O26) infections.
- In the initial, larger outbreak, 55 people infected with the outbreak strain of STEC O26 were reported from 11 states. Twenty-one ill people were hospitalized.
- In the second, smaller outbreak, 5 people infected with a different strain of STEC O26 were reported from 3 states. One ill person was hospitalized.
- There were no reports of hemolytic uremic syndrome and no deaths in either outbreak.
- Investigators used whole genome sequencing (WGS), an advanced laboratory technique, to get more detailed information about the DNA fingerprints of the STEC O26 bacteria that caused illness.
- Isolates tested from ill people in the second, smaller outbreak were not related genetically to isolates from ill people in the initial, larger outbreak.
- The epidemiologic evidence collected during this investigation suggested that a common meal item or ingredient served at Chipotle Mexican Grill restaurants was a likely source of both outbreaks. The investigation did not identify a specific food or ingredient linked to illness.
- Most ill people in these outbreaks ate many of the same food items at a Chipotle Mexican Grill restaurant. When a restaurant serves foods with several ingredients that are mixed or cooked together and then used in multiple menu items, it can be more difficult for epidemiologic studies to identity the specific ingredient that is contaminated.
- Testing of multiple food items collected from Chipotle restaurant locations did not identify STEC O26.
- A review of Chipotle's distribution records by state and federal regulatory officials was unable to identify a single food item or ingredient that could explain either outbreak.
- Food industries are an important partner in making food safer for everyone. They can help stop outbreaks and lessen their impact by keeping detailed records to allow faster tracing of individual shipments of foods from source to destination and to help investigators identify what made people sick.
- Take action if you think you have a foodborne illness, such as talking to your healthcare provider, writing down what you ate in the week before you got sick, and answering questions about your illness when public health investigators contact you.
Outbreak Summary
Introduction
CDC, the U.S. Food and Drug Administration, the U.S. Department of Agriculture's Food Safety and Inspection Service, and public health officials in several states investigated two outbreaks of Shiga toxin-producing Escherichia coli O26 (STEC O26) infections.
Public health investigators used the PulseNet system to identify illnesses that were part of the outbreaks. PulseNet, the national subtyping network of public health and food regulatory agency laboratories, is coordinated by CDC. DNA fingerprinting is performed on E. coli bacteria isolated from ill people by using a technique called pulsed-field gel electrophoresis, or PFGE. PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. Two different, rare DNA fingerprints of STEC O26 were included in these investigations. Investigators also used whole genome sequencing (WGS), an advanced laboratory technique, to get more detailed information about the DNA fingerprints of the two STEC O26 strains that caused illness.
Summaries of the two outbreaks are provided in more detail below.
Initial, Larger Outbreak
The initial, larger outbreak was first detected by public health officials in Washington and Oregon through local foodborne disease surveillance. In late October 2015, officials in those states detected an increase in illness and after interviewing ill people, they determined that illness was likely linked to eating at multiple Chipotle Mexican Grill locations.
PFGE results from ill people in Washington and Oregon indicated that people were infected with a rare strain of STEC O26. A search of the PulseNet database identified illnesses in other states, and these ill people were added to the total case count.
A total of 55 people infected with the outbreak strain of STEC O26 were reported from 11 states. The majority of illnesses were reported from Washington and Oregon during October 2015. The number of ill people reported from each state was as follows: California (3), Delaware (1), Illinois (1), Kentucky (1), Maryland (1), Minnesota (2), New York (1), Ohio (3), Oregon (13), Pennsylvania (2), and Washington (27).
Among people for whom information was available, illnesses started on dates ranging from October 19, 2015 to December 1, 2015. Ill people ranged in age from 1 year to 94, with a median age of 21. Fifty-seven percent of ill people were female. Twenty-one (38%) people reported being hospitalized. There were no reports of hemolytic uremic syndrome and no deaths.
WGS was performed on 36 STEC O26 isolates from ill people in this outbreak, including isolates from ill people in states outside the Pacific Northwest. All 36 isolates were highly related genetically. This provided additional evidence that illnesses outside the Pacific Northwest were related to the earlier illnesses in Oregon and Washington.
Second, Smaller Outbreak
In December 2015, a second outbreak of a different, rare strain of STEC O26 was identified. A total of five people infected with this strain of STEC O26 were reported from three states. The number of ill people reported from each state was as follows: Kansas (1), North Dakota (1), and Oklahoma (3).
Among people for whom information was available, illnesses started on dates ranging from November 18, 2015 to November 26, 2015. Ill people ranged in age from 6 years to 25, with a median age of 22. Eighty percent of ill people were female. One (20%) person reported being hospitalized. There were no reports of hemolytic uremic syndrome and no deaths.
WGS was performed on four STEC O26 isolates from ill people in this outbreak. All four isolates were highly related genetically to each other, but they were not related to isolates from ill people in the initial, larger outbreak.
Investigation of the Outbreaks
The epidemiologic evidence collected during these investigations suggested that a common meal item or ingredient served at Chipotle Mexican Grill restaurants was a likely source of both outbreaks. The investigations did not identify a specific food or ingredient linked to illness in either outbreak.
State and local public health officials interviewed ill people to obtain information about foods they might have eaten and other exposures in the week before their illness started. In the initial, larger outbreak, 47 (87%) of 54 people interviewed reported eating at a Chipotle Mexican Grill restaurant. This included at least 17 different restaurant locations in 8 states. In the smaller outbreak, five (100%) of five people interviewed reported eating at a Chipotle Mexican Grill restaurant. All three ill people in Oklahoma ate at a single Chipotle location in that state. The ill person in North Dakota traveled to Kansas during the exposure period and ate at the same Chipotle location as the ill person in Kansas.
The data collected during interviews with ill people indicated that most ate a meal at a Chipotle Mexican Grill in the week before illness started, and they ate many of the same items. The Oregon and Washington Departments of Health conducted epidemiologic studies in the initial outbreak that compared foods eaten by ill and well people at Chipotle Mexican Grill. Those studies did not identify any specific food item or ingredient that could explain the outbreak. When a restaurant serves foods with several ingredients that are mixed or cooked together and then used in multiple menu items, it can be more difficult for epidemiologic studies to identify the specific ingredient that is contaminated.
Testing of multiple food items collected from Chipotle restaurant locations did not identify STEC O26.
A review of Chipotle's distribution records by state and federal regulatory officials was unable to identify a single food item or ingredient that could explain illnesses in either outbreak. Food industries are an important partner in making food safer for everyone. They can help stop outbreaks and lessen their impact by keeping detailed records to allow faster tracing of individual shipments of foods from source to destination.
February 1, 2016
Final Case Count Update
Since the last update on December 21, two more ill people were reported from Delaware and Kentucky in the initial, larger outbreak. These illnesses started on November 17, 2015 and December 1, 2015. No additional ill people were reported in the smaller outbreak of five cases.
December 21, 2015
Case Count Update
Since the last update on December 4, one more ill person has been reported from Pennsylvania. This person did not report eating at Chipotle Mexican Grill in the week before November 14, 2015, when illness started.
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).
Among people for whom information is available, illnesses started on dates ranging from October 19, 2015 to November 14, 2015. Ill people range in age from 1 year to 94, with a median age of 21. Fifty-nine percent of ill people are female. Twenty (38%) people reported being hospitalized. There have been no reports of hemolytic uremic syndrome and no deaths.
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. Please see the Timeline for Reporting Cases of E. coli Infection for more details.
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.
Investigation Update
State and local public health officials continue to interview ill people to obtain information about foods they might have eaten and other exposures in the week before their illness started. To date, 46 (88%) of 52 people interviewed reported eating at a Chipotle Mexican Grill restaurant. The investigation is still ongoing to identify common meal items or ingredients causing illness.
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.
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. It is not known if these infections are related to the larger outbreak of STEC O26 infections; this investigation is ongoing. WGS is being used to determine if this strain is genetically related to the STEC O26 causing the larger outbreak.
Updates will be provided when more information is available.
December 4, 2015
Case Count Update
Since the last update on November 20, seven more ill people have been reported from California (1), Illinois (1), Maryland (1), Ohio (2), Pennsylvania (1), and Washington (1).
Fifty-two 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 (1), and Washington (27).
Among people for whom information is available, illnesses started on dates ranging from October 19, 2015 to November 13, 2015. Ill people range in age from 1 year to 94, with a median age of 21. Fifty-nine percent of ill people are female. Twenty (38%) people reported being hospitalized. There have been no reports of hemolytic uremic syndrome and no deaths.
Illnesses that occurred after November 11, 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. Please see the Timeline for Reporting Cases of E. coli Infection for more details.
CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill people and to interview them.
Investigation Update
State and local public health officials continue to interview ill people to obtain information about foods they might have eaten and other exposures in the week before their illness started. To date, 47 (90%) of 52 people interviewed reported eating at a Chipotle Mexican Grill restaurant. Of the three most recent illnesses reported in November, only one ill person, whose illness started on November 10, reported eating at Chipotle Mexican Grill in the week before their illness began. The investigation is still ongoing to identify common meal items or ingredients causing illness.
Investigators are also using whole genome sequencing, an advanced laboratory technique, to get more information about the DNA fingerprint of the STEC O26 bacteria causing illness. To date, whole genome sequencing has been performed on STEC O26 isolates from 21 ill people in Washington (16), California (2), Minnesota (2), and New York (1). All 21 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.
Updates will be provided when more information is available.
November 20, 2015
Case Count Update
CDC is only reporting ill people that have been confirmed by PulseNet as being infected with the outbreak strain of Shiga toxin-producing Escherichia coli O26 (STEC O26). Forty-five people infected with the outbreak strain of STEC O26 have been reported from 6 states. The majority of illnesses have been reported from Washington and Oregon. The number of ill people reported from each state is as follows: California (2), Minnesota (2), New York (1), Ohio (1), Oregon (13), and Washington (26).
Among people for whom information is available, illnesses started on dates ranging from October 19, 2015 to November 8, 2015. Ill people range in age from 2 years to 94, with a median age of 22. Fifty-eight percent of ill people are female. Sixteen (36%) people reported being hospitalized. There have been no reports of hemolytic uremic syndrome and no deaths.
This outbreak can be illustrated with a chart showing the number of people who became ill each day. This chart is called an epidemic curve or epi curve. Illnesses that occurred after October 31, 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. Please see the Timeline for Reporting Cases of E. coli Infection for more details.
CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview them.
Investigation Update
CDC, the U.S. Food and Drug Administration, and public health officials in several states are investigating an outbreak of Shiga toxin-producing Escherichia coli O26 (STEC O26) infections.
The epidemiologic evidence available to investigators at this time suggests that a meal item or ingredient served at Chipotle Mexican Grill restaurants at several states is a likely source of this outbreak. The investigation has not identified what specific food is linked to illness. Chipotle Mexican Grill is assisting public health officials with understanding the distribution of food items served at locations where ill people ate and this work is ongoing.
State and local public health officials are interviewing ill people to obtain information about foods they might have eaten and other exposures in the week before their illness started. Forty-three (96%) of 45 people interviewed reported eating at a Chipotle Mexican Grill restaurant. The investigation is ongoing to identify common meal items or ingredients causing illness.
Investigators are also using whole genome sequencing, an advanced laboratory technique, to get more information about the DNA fingerprint of the STEC O26 bacteria causing illness. To date, whole genome sequencing has been performed on STEC O26 isolates from 9 ill people in Washington and 1 ill person in Minnesota. All 10 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.
Updates will be provided when more information is available.
November 17, 2015
Case Count Update
Thirty-seven people infected with the outbreak strain of STEC O26 have been reported to CDC PulseNet from Washington (24) and Oregon (13). Thirteen of these people were hospitalized in Washington (9) and Oregon (4). There have been no reports of hemolytic uremic syndrome (HUS) and no deaths. Additional illnesses are under investigation by Washington and Oregon and will be reported if they are confirmed to be infected with the outbreak strain of STEC O26. There have been no reported infections with the outbreak strain of STEC O26 in Washington or Oregon since the Chipotle Mexican Grill locations closed in the Pacific Northwest on October 30, 2015.
Also, as reported on November 6, a search of the PulseNet database identified one person in Minnesota infected with STEC O26 that has the same DNA fingerprint. This ill person did not eat at a Chipotle Mexican Grill in the week before illness onset. Minnesota's investigation is ongoing. The illness does not appear to be linked to Chipotle Mexican Grill locations in Washington and Oregon.
CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview them. Updates will be provided when more information is available. Investigators are using whole genome sequencing, an advanced laboratory technique, to get more information about the DNA fingerprint of the germ causing illnesses in Washington, Oregon, and Minnesota.
November 12, 2015
Case Count Update
Fifty ill people have been reported from Washington (31) and Oregon (19). Fourteen people have been hospitalized in Washington (10) and Oregon (4). There have been no reports of hemolytic uremic syndrome (HUS) and no deaths.
Thirty-three isolates from ill people in Washington (22) and Oregon (11) have been uploaded to the CDC PulseNet database. All 33 people were infected with STEC O26 that has the same DNA fingerprint. Additionally, as reported on November 6, a search of the PulseNet database identified one person in Minnesota infected with STEC O26 that has the same DNA fingerprint. This ill person did not eat at a Chipotle Mexican Grill in the week before illness onset. Minnesota’s investigation is ongoing. The illness does not appear to be related to the outbreak in Washington and Oregon linked to Chipotle Mexican Grill locations in those states. Whole genome sequencing, an advanced laboratory technique, is being used to give investigators more information about the DNA fingerprint of the pathogen causing illnesses in Washington, Oregon, and Minnesota.
CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview them. Updates will be provided when more information is available.
Investigation Update
The investigation is still ongoing to determine if the ill people ate a meal item or ingredient in common that was served at the Chipotle Mexican Grill locations. Several food items collected from Chipotle Mexican Grill locations in Washington and Oregon are being tested by FDA and Chipotle for the presence of bacteria. As of November 12, 2015, test results have not identified E. coli in any of the food items tested. Additional results are pending and will be reported once available.
On November 11, 2015, Chipotle Mexican Grill began to reopen its restaurants in Washington and multiple locations in the Portland, Oregon area that had been closed since October 30, 2015 in response to this investigation. Most restaurants have been reopened, with the others reopening in the coming days. Chipotle agreed to carry out a range of food safety actions recommended by Washington and Oregon before reopening these restaurant locations.
November 9, 2015
Case Count Update
Twenty-three isolates from ill people in Washington (16) and Oregon (7) have been uploaded to the CDC PulseNet database. All 23 people were infected with STEC O26 that has the same DNA fingerprint. Additionally, as reported on November 6, a search of the PulseNet database identified one person in Minnesota infected with STEC O26 that has the same DNA fingerprint. This ill person did not eat at a Chipotle Mexican Grill in the week before illness onset. Minnesota’s investigation is ongoing. The illness does not appear to be related to the outbreak in Washington and Oregon linked to Chipotle Mexican Grill locations in those states. Whole genome sequencing, an advanced laboratory technique, is being used to give investigators more information about the DNA fingerprint of the pathogen causing illnesses in Washington, Oregon, and Minnesota.
Forty-two ill people have been reported from Washington (27) and Oregon (15). Fourteen people have been hospitalized in Washington (10) and Oregon (4). There have been no reports of hemolytic uremic syndrome (HUS) and no deaths.
CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview them. Updates will be provided when more information is available.
November 6, 2015
Case Count Update
Sixteen isolates from ill people in Washington (13) and Oregon (3) have been uploaded to the CDC PulseNet database. All 16 people were infected with STEC O26 that has the same DNA fingerprint. A search of the PulseNet database identified one person in Minnesota infected with STEC O26 that has the same DNA fingerprint. This ill person did not eat at a Chipotle Mexican Grill in the week before illness onset. Minnesota's investigation is ongoing. At this time, the illness does not appear to be related to the outbreak in Washington and Oregon. Whole genome sequencing, an advanced laboratory technique, is being used to give investigators more information about the DNA fingerprint of the pathogen causing illnesses in Washington, Oregon, and Minnesota.
Forty-one ill people have been reported from Washington (28) and Oregon (13). Fourteen people have been hospitalized in Washington (10) and Oregon (4). There have been no reports of hemolytic uremic syndrome (HUS) and no deaths.
CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview them. Updates will be provided when more information is available.
November 5, 2015
Case Count Update
Ten isolates from ill people in Washington (7) and Oregon (3) have been uploaded to the CDC PulseNet database. All 10 people were infected with STEC O26 that has the same DNA fingerprint. CDC conducted a preliminary search of the PulseNet database and did not find other illnesses that appear to be related to the outbreak in Washington and Oregon. Laboratory testing is continuing.
Forty ill people have been reported from Washington (28) and Oregon (12). Twelve people have been hospitalized: 10 in Washington and 2 in Oregon. There have been no reports of hemolytic uremic syndrome (HUS) and no deaths.
CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview them. Updates will be provided when more information is available.
November 4, 2015
Initial Announcement
The Washington State Department of Health and the Oregon Health Authority are investigating an outbreak of Shiga toxin-producing Escherichia coli O26 (STEC O26) infections. CDC and the U.S. Food and Drug Administration (FDA) are assisting with the investigation.
Public health investigators are using the PulseNet system to identify illnesses that may be part of these outbreaks. PulseNet, the national subtyping network of public health and food regulatory agency laboratories, is coordinated by CDC. DNA "fingerprinting" is performed on E. coli bacteria isolated from ill people by using a technique called pulsed-field gel electrophoresis, or PFGE. PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks.
As of November 4, 2015, one DNA fingerprint (outbreak strain) of STEC O26 is included in this outbreak investigation. Five isolates from ill people in Washington (2) and Oregon (3) have been uploaded to the CDC PulseNet database. All five people were infected with STEC O26 that has the same DNA fingerprint. CDC conducted a preliminary search of the PulseNet database and did not find any illnesses that appear to be related to the outbreak in Washington and Oregon. Laboratory testing is continuing.
As reported by Washington and Oregon, 39 ill people have been reported from Washington (29) and Oregon (10) as of November 4, 2015. Fourteen total ill people in Washington (11) and Oregon (3) have been hospitalized. There have been no reports of hemolytic uremic syndrome (HUS) and no deaths.
Washington and Oregon report that most of the ill people ate at several locations of Chipotle Mexican Grill before getting sick. The investigation is ongoing to determine if the ill people ate a common meal item or ingredient that was served at the restaurant locations. Chipotle Mexican Grill voluntarily closed all of its locations in Washington and multiple locations in the Portland, Oregon area until more information is available. At this time, CDC does not have any information to suggest that Chipotle Mexican Grill locations in other states are affected by this outbreak.
FDA is testing several different food items collected from Chipotle Mexican Grill locations in Washington and Oregon for the presence of bacteria. Results of this testing will be reported once it is available.
CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview them. Updates will be provided when more information is available.
At A Glance
More Information
- Page last reviewed: November 20, 2015
- Page last updated: February 1, 2016
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