Outbreak Investigation Updates by Date

Posted December 4, 2019 at 3:00 PM ET

November 26, 2019

Since the previous update on November 22, an additional 27 ill people have been reported. As of November 25, 2019, a total of 67 people infected with the outbreak strain of E. coli O157:H7 have been reported from 19 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Illnesses started on dates ranging from September 24, 2019, to November 14, 2019. Ill people range in age from 3 to 89 years, with a median age of 25. Sixty-seven percent of ill people are female. Of 50 ill people with information available, 39 hospitalizations have been reported, including six people who developed hemolytic uremic syndrome (HUS), a type of kidney failure. No deaths have been reported.

Investigation of the Outbreak

Epidemiologic, laboratory, and traceback evidence indicate that romaine lettuce from the Salinas, California, growing region is the likely source of this outbreak.

FDA and states continue to trace the source of the romaine lettuce eaten by ill people. Preliminary information indicates that some of the ill people ate lettuce grown in Salinas, California. No common grower, supplier, distributor, or brand of romaine lettuce has been identified.

CDC continues to advise that consumers not eat and retailers not sell any romaine lettuce grown in Salinas, California. The investigation is ongoing to determine the source of contamination and if additional products are linked to illness.

This outbreak is caused by the same strain of E. coli O157:H7 that caused outbreaks linked to leafy greens in 2017 and to romaine lettuce in 2018.

November 22, 2019

Since the initial investigation notice, 23 additional ill people have been reported. As of November 21, 2019, a total of 40 people infected with the outbreak strain of E. coli O157:H7 have been reported from 16 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Illnesses started on dates ranging from September 24, 2019, to November 10, 2019. Ill people range in age from 3 to 89 years, with a median age of 22. Sixty-five percent of ill people are female. Of 39 ill people with information available, 28 hospitalizations have been reported, including 5 people who developed hemolytic uremic syndrome (HUS), a type of kidney failure. No deaths have been reported.

Investigation of the Outbreak

Epidemiologic, laboratory, and traceback evidence indicate that romaine lettuce from the Salinas, California growing region is a likely source of this outbreak.

In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. Eight (80%) of 10 people interviewed reported eating romaine lettuce. This percentage is significantly higher than results from a survey pdf icon[PDF – 787 KB] of healthy people in which 47% reported eating romaine lettuce in the week before they were interviewed. Ill people in Maryland reported eating Ready Pac Foods Bistro® Chicken Caesar Salad. To date, ill people in other states have not reported eating this particular salad, which contained romaine lettuce from the Salinas, California growing region.

As reported on November 20, 2019, the Maryland Department of Healthexternal icon identified E. coli O157 in romaine lettuce from an unopened package of Ready Pac Foods Bistro® Chicken Caesar Salad collected from a sick person’s home in Maryland. Whole genome sequencing has been completed and shows that the E. coli strain in the romaine lettuce is closely related genetically to the E. coli found in sick people in this outbreak. This provides additional evidence that people in this outbreak got sick from eating romaine lettuce.

FDA and states are tracing the source of the romaine lettuce eaten by ill people. Preliminary information indicates that some of the ill people ate lettuce grown in Salinas, California. No common grower, supplier, distributor, or brand of romaine lettuce has been identified.

CDC is advising that consumers not eat and retailers not sell any romaine lettuce harvested from Salinas, California until more information is available. The investigation is ongoing to determine the source of contamination and if additional products are linked to illness.

This outbreak is caused by the same strain of E. coli O157:H7 that caused outbreaks linked to leafy greens in 2017 and to romaine lettuce in 2018.

November 20, 2019

CDC, public health and regulatory officials in several states, and the US Food and Drug Administrationexternal icon (FDA) are investigating a multistate outbreak of Shiga toxin-producing E. coli (STEC) O157:H7 infections. This investigation includes illnesses recently reported by the Maryland Department of Healthexternal icon and Wisconsin Department of Health Services.external icon

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA fingerprinting is performed on E. coli bacteria isolated from ill people by using a standardized laboratory and data analysis method called whole genome sequencing (WGS). CDC PulseNet manages a national database of these sequences that are used to identify possible outbreaks. WGS gives investigators detailed information about the bacteria causing illness. In this investigation, WGS showed that bacteria isolated from ill people were closely related genetically. This means that people in this outbreak are more likely to share a common source of infection.

As of November 18, 2019, a total of 17 people infected with the outbreak strain of E. coli O157:H7 have been reported from 8 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Illnesses started on dates ranging from September 24, 2019, to November 8, 2019. Ill people range in age from 3 to 72 years, with a median age of 16. Fifty-six percent of ill people are female. Of 17 ill people with information available, 7 hospitalizations have been reported, including 2 people who developed hemolytic uremic syndrome (HUS), a type of kidney failure. No deaths have been reported.

The Maryland Department of Healthexternal icon identified E. coli O157 in an unopened package of Ready Pac Foods Bistro® Chicken Caesar Salad collected from a sick person’s home in Maryland. The salad had a “Best By” date of October 31, 2019. WGS is currently underway in Maryland for this sample to determine if it is closely related genetically to the E. coli found in people in this outbreak.

State and local public health officials are interviewing ill people to determine what they ate and other exposures in the week before their illness started. Ill people in Maryland reported eating Ready Pac Foods Bistro® Chicken Caesar Salad. In initial interviews, ill people in other states have not reported eating this particular salad.

FDA is tracing back the supply of the romaine lettuce in the salad and has identified possible farms in Salinas, California. Preliminary information indicates that romaine lettuce used in the product that tested positive was harvested in mid-October and is no longer within current expiration dates.

The investigation is ongoing to determine the source of contamination and if additional products are linked to illness. CDC will provide more information as it becomes available.