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Outbreak of E. coli Infections Linked to Romaine Lettuce

Final Update

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Posted January 9, 2019 at 4:30 PM ET


This outbreak appears to be over. E. coli is an important cause of 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 E. coli and Food Safety web page.


CDC, public health and regulatory officials in several states, Canada, and the U.S. Food and Drug Administration (FDA) investigated a multistate outbreak of Shiga toxin-producing Escherichia coli O157:H7 (E. coli O157:H7) infections linked to romaine lettuce from the Central Coastal growing regions in northern and central California. This outbreak appears to be over.

Advice to Consumers, Restaurants, and Retailers

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On December 13, 2018, Adam Bros. Farming, Inc., in Santa Barbara County recalled [PDF – 10.1 KB] red leaf lettuce, green leaf lettuce, and cauliflower harvested November 27-30, 2018, because they may be contaminated with E. coli O157:H7. Do not eat, sell, or serve any recalled products.

  • As a result of this recall, Spokane Produce, Inc. of Spokane, Washington recalled sandwiches and other products under the Northwest Cuisine Creations and Fresh & Local labels.

Contaminated lettuce that made people sick in this outbreak should no longer be available.

  • Take action if you have symptoms of an E. coli infection:
    • 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.
  • Follow these steps to help keep you healthy and your fruits and vegetables safer to eat:
    • Wash your hands before and after preparing fruits and vegetables.
    • Wash or scrub all fruits and vegetables under running water before eating, cutting, or cooking.
      • Fruits and vegetables labeled “prewashed” do not need to be washed again at home.
    • Use separate cutting boards for fruits and vegetables and for raw meats, poultry, seafood, or eggs.
    • Use separate plates and utensils for cooked and raw foods.
    • Store fruits and vegetables away from, and not next to or below, raw meat, poultry, or seafood. These items can drip juices that may have germs.
  • Follow these general ways to prevent E. coli infection:
    • Wash your hands. E. coli infections can spread from one person to another. Wash hands after using the restroom or changing diapers, before and after preparing or eating food, and after contact with animals.
    • Don’t prepare food or drink for others when you are sick.
    • Cook meats thoroughly to kill harmful germs. Cook steaks and roasts to at least 145˚F and let rest for 3 minutes after you remove meat from the grill or stove. Cook ground beef and pork to at least 160˚F. Use a food thermometer to check the temperature of the meat.
    • Don’t spread germs from raw meat around food preparation areas. Thoroughly wash hands, counters, cutting boards, and utensils after they touch raw meat.
    • Avoid raw milk, other unpasteurized dairy products, and unpasteurized juices.

Advice to Clinicians

  • Antibiotics are not recommended for patients with E. coli O157 infections. Antibiotics are also not recommended for patients in whom E.coli O157 infection is suspected, until diagnostic testing rules out this infection.
  • Some studies have shown that administering antibiotics to patients with E. coli O157 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.

Final Outbreak Information

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At A Glance

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  • This outbreak appears to be over as of January 9, 2019.
  • Sixty-two people infected with the outbreak strain of Shiga toxin-producing E. coli O157:H7 were reported from 16 states and the District of Columbia.
    • Illnesses started on dates ranging from October 7, 2018, to December 4, 2018.
    • Twenty-five people were hospitalized, including two people who developed hemolytic uremic syndrome, a type of kidney failure. No deaths were reported.
  • The Public Health Agency of Canada identified ill people infected with the same DNA fingerprint of E. coli O157:H7 bacteria in Canada.
  • Epidemiologic, laboratory, and traceback evidence from the United States and Canada indicated that romaine lettuce harvested from the Central Coastal growing regions of northern and central California was the likely source of the outbreak.
  • The FDA, along with CDC and state partners, investigated farms and cooling facilities in California that were identified in traceback. CDC identified the outbreak strain of E. coli O157:H7 in sediment collected within an agricultural water reservoir on an Adam Bros. Farming Inc. farm in Santa Barbara County, which was identified in the traceback investigation.

Symptoms of E. coli Infection

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  • People usually get sick from Shiga toxin-producing E. 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. coli infection is usually diagnosed by testing a stool sample.
  • Antibiotics are not recommended for patients with suspected E. coli infections until diagnostic testing can be performed and E. coli infection is ruled out. Some studies have shown that administering antibiotics to patients with E. coli infections might increase their risk of developing HUS, and a benefit of treatment has not been clearly demonstrated.
  • For more information, see Symptoms of E. coli Infection.

Investigation Details

January 9, 2019

CDC, public health and regulatory officials in several states, Canada, and the FDA investigated a multistate outbreak of Shiga toxin-producing Escherichia coli O157:H7 (E. coli O157:H7) infections.

Public health investigators used the PulseNet system to identify illnesses that might be part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA fingerprinting was performed on E. coli bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole 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 on E. coli bacteria 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 January 9, 2019, 62 people infected with the outbreak strain of E. coli O157:H7 were reported from 16 states and the District of Columbia. 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 October 7, 2018, to December 4, 2018. Ill people ranged in age from 1 to 84 years, with a median age of 25. Sixty-six percent of ill people were female. Of 54 people with information available, 25 (46%) were hospitalized, including two people who developed hemolytic uremic syndrome, a type of kidney failure. No deaths were reported.

WGS analysis did not identify predicted antibiotic resistance in 51 isolates from 53 ill people. Two isolates contained genes for resistance to ampicillin. Antibiotic resistance testing by CDC’s National Antimicrobial Resistance Monitoring System laboratory is currently underway. This finding does not affect treatment guidance since antibiotics are not recommended for patients with E. coli O157 infections.

Investigation of the Outbreak

Epidemiologic, laboratory, and traceback evidence indicated that romaine lettuce from the Central Coastal growing regions of northern and central California was the 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. Thirty (83%) of 36 people interviewed reported eating romaine lettuce. This percentage was significantly higher than results from a survey [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.

Two illness clusters were identified at restaurants where ill people reported eating romaine lettuce. An illness cluster is defined as two or more people who do not live in the same household who report eating at the same restaurant location, attending a common event, or shopping at the same location of a grocery store in the week before becoming ill. In these two clusters, several ill people reported eating at the same restaurant or shopping at the same location of a grocery store. Investigating illness clusters provides critical clues about the source of an outbreak. If several unrelated ill people ate or shopped at the same location of a restaurant or store within several days of each other, it suggests that the contaminated food item was served or sold there.

Traceback information from the FDA indicated that ill people in this outbreak ate romaine lettuce harvested from specific counties in the Central Coastal growing regions of northern and central California. The FDA, along with CDC and state partners, investigated farms and cooling facilities in California that were identified in traceback. CDC analyzed water and sediment samples from an Adam Bros. Farming, Inc. farm in Santa Barbara County, which was one of the farms identified in the traceback investigation. The outbreak strain of E. coli O157:H7 was found in sediment within an agricultural water reservoir on the farm. WGS results showed that the E. coli O157:H7 found in the agricultural water reservoir was closely related genetically to the E. coli O157:H7 isolated from ill people.

WGS results also showed that the E. coli O157:H7 strain isolated from ill people in this outbreak is closely related genetically to the E. coli strain isolated from ill people in a 2017 outbreak linked to leafy greens in the United States and to romaine lettuce in Canada. The outbreak described here is not related to a spring 2018 multistate outbreak of E. coli O157:H7 infections linked to romaine lettuce. People in the spring outbreak were infected with E. coli O157:H7 bacteria with a different DNA fingerprint.

FDA is continuing to investigate to learn more about how the E. coli bacteria could have entered the agricultural water reservoir and ways romaine lettuce from the farm could have been contaminated. The FDA is able to confirm that Adam Bros. Farming, Inc. has not shipped romaine since November 20, 2018. Romaine lettuce from Adam Bros. Farming, Inc. linked to this outbreak is no longer available for sale.

FDA continues its investigation of farms identified in traceback.

As of January 9, 2019, this outbreak appears to be over.

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