Press Release, Center for Disease Control (CDC)

CDC, public health and regulatory officials in several states, Canada, and the FDA are investigating a multistate outbreak of Shiga toxin-producingEscherichia coliO157:H7 (E. coliO157:H7) infections.

Public health investigators are using thePulseNetsystem 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 onE. colibacteria isolated from ill people by using techniques calledpulsed-field gel electrophoresis(PFGE) andwhole genome sequencing(WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. WGS gives a more detailed DNA fingerprint than PFGE. WGS performed onE. colibacteria from ill people in this outbreak showed that the strains were closely related genetically. This means that the ill people were more likely to share a common source of infection.

As of November 20, 2018, 32 people infected with the outbreak strain ofE. coliO157:H7 have been reported from 11 states. A list of the states and the number of cases in each can be found on theMap of Reported Cases page.

Illnesses started on dates ranging fromOctober 8, 2018 to October 31, 2018. Ill people range in age from 7 to 84 years, with a median age of 24. Sixty-six percent of ill people are female. Of 26 people with information available, 13 (50%) were hospitalized, including one person who developed hemolytic uremic syndrome, a type of kidney failure. No deaths have been reported.

Illnesses that occurred after October 30, 2018, might not yet be reported due to the time it takes between when a person becomes ill withE. coliinfection and when the illness is reported. This takes an average oftwo to three weeks.

Investigation of the Outbreak

Epidemiologic evidenceindicates that romaine lettuce is a likely source of this outbreak.

In interviews, ill people answeredquestions about the foods they ate and other exposuresin the week before they became ill. Eleven (79%) of 14 people interviewed reported eating romaine lettuce. This percentage is significantly higher than results from asurvey[PDF – 787 KB]of healthy people in which 47% reported eating romaine lettuce in the week before they were interviewed. Ill people reported eating different types of romaine lettuce in several restaurants and at home.

Whole genome sequencing (WGS) results showed that theE. coliO157:H7 strain isolated from ill people in this outbreak is closely related genetically to theE. colistrain isolated from ill people in a 2017 outbreak linked toleafy greensin the United States and toromaine lettuce in Canada. The current outbreak is not related to a recent multistate outbreak ofE. coliO157:H7 infections linked toromaine lettuce. People in the spring outbreak were infected withE. coliO157:H7 bacteria with a different DNA fingerprint.

FDA and states are working to trace back romaine lettuce that ill people ate in the current outbreak. At this time, no common grower, supplier, distributor, or brand of romaine lettuce has been identified. CDC is advising that consumers not eat any romaine lettuce, and restaurants and retailers not sell any, until we learn more about this outbreak and the source of the contaminated lettuce.

This investigation is ongoing, and CDC will provide more information as it becomes available.

CDC is advising that U.S. consumers not eat any romaine lettuce, and retailers and restaurants not serve or sell any, until we learn more about the outbreak. This investigation is ongoing and the advice will be updated as more information is available.

  • Consumers who have any type of romaine lettuce in their home should not eat it and should throw it away, even if some of it was eaten and no one has gotten sick.
    • This advice includes all types or uses of romaine lettuce, such as whole heads of romaine, hearts of romaine, and bags and boxes of precut lettuce and salad mixes that contain romaine, including baby romaine, spring mix, and Caesar salad.
    • If you do not know if the lettuce is romaine or whether a salad mix contains romaine, do not eat it and throw it away.
    • Wash and sanitize drawers or shelves in refrigerators where romaine was stored. Follow thesefive stepsto clean your refrigerator.
  • Restaurants and retailers should not serve or sell any romaine lettuce, including salads and salad mixes containing romaine.
  • Take actionif you havesymptoms of anE. coliinfection:
    • Talk to your healthcare provider.
    • Write down what you ate in the week before you started to get sick.
    • Report your illness to the health department.
    • Assist public health investigators by answering questions about your illness.

Advice to Clinicians

  • Antibiotics are not recommendedfor patients withE. coliO157 infections. Antibiotics are also not recommended for patients in whomE.coliO157 infection is suspected, until diagnostic testing rules out this infection.
  • Some studies have shown that administering antibiotics to patients withE. coliO157 infections might increase their risk of developing hemolytic uremic syndrome (a type of kidney failure), and the benefit of antibiotic treatment has not been clearly demonstrated.

Latest Outbreak Information

At A Glance

Photo of romaine lettuce in a wood bowl.
  • Thirty-two people infected with the outbreak strain of Shiga toxin-producingE. coliO157:H7 have been reported from 11 states.
    • Illnesses started on dates ranging from October 8, 2018 to October 31, 2018.
    • Thirteen people were hospitalized, including one person who developed hemolytic uremic syndrome, a type of kidney failure. No deaths have been reported.
  • ThePublic Health Agency of Canadahas identified 18 ill people infected with the same DNA fingerprint ofE. coliO157:H7 bacteria in two Canadian provinces: Ontario and Quebec.
  • Epidemiologic evidencefrom the United States and Canada indicates that romaine lettuce is a likely source of the outbreak.
  • Ill people in this outbreak were infected withE. colibacteria with the same DNA fingerprint as theE. colistrain isolated from ill people in a 2017 outbreak linked toleafy greensin the United States and toromaine lettuce in Canada. The current outbreak is not related to a recent multistate outbreak ofE. coliO157:H7 infections linked toromaine lettuce.
  • CDC is advising that consumers do not eat any romaine lettuce because no common grower, supplier, distributor, or brand of romaine lettuce has been identified.
  • This investigation is ongoing, and CDC will provide more information as it becomes available.

Symptoms ofE. coliInfection

Illustration of a person with stomach pain.
  • People usually get sick from Shiga toxin-producingE. coli(STEC) 2–8 days (average of 3–4 days) after swallowing the germ.
  • Some people with a STEC infection may get a type of kidney failure called hemolytic uremic syndrome (HUS).
  • E. coliinfection is usually diagnosed by testing a stool sample.
  • Antibiotics are not recommended for patients with suspectedE. coliinfections until diagnostic testing can be performed andE. coliinfection is ruled out. Some studies have shown that administering antibiotics to patients withE. coliinfections might increase their risk of developing HUS, and a benefit of treatment has not been clearly demonstrated.
  • For more information, seeSymptoms ofE. coliInfection.