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Outbreak of E. coli Infections Linked to Romaine Lettuce

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Posted December 6, 2018 at 3:45 PM ET

CDC, public health and regulatory officials in several states, Canada, and the U.S. Food and Drug Administration (FDA) are investigating 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.

Advice to Consumers, Restaurants, and Retailers

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On November 26, 2018, CDC updated its warning to consumers. CDC continues to advise that U.S. consumers not eat and retailers and restaurants not serve or sell any romaine lettuce harvested from the Central Coastal growing regions of northern and central California. If you do not know where the romaine is from, do not eat it.

  • Some romaine lettuce products are now labeled with a harvest location by region. Consumers, restaurants, and retailers should check bags or boxes of romaine lettuce for a label indicating where the lettuce was harvested.
    • If the romaine lettuce is not labeled with a harvest growing region, do not buy, serve, sell, or eat it.
    • Romaine lettuce labeled with a harvest region outside of the Central Coastal growing regions of northern and central California is not linked to the outbreak. Areas not linked to this outbreak include the desert growing region near Yuma, Arizona; the California desert growing region near Imperial County and Riverside County; the state of Florida; and Mexico.
  • If you purchased romaine lettuce and do not know where it was harvested, do not eat, serve, or sell it and throw it away.
    • 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.
    • Wash and sanitize drawers or shelves in refrigerators where romaine was stored. Follow these five steps to clean your refrigerator.
    • 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.
  • Hydroponic or greenhouse-grown romaine lettuce has not been linked to this outbreak.
  • 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.

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.

Latest Outbreak Information

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At A Glance

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  • Since the last update on November 26, an additional nine ill people have been included in this investigation.
  • Fifty-two people infected with the outbreak strain of Shiga toxin-producing E. coli O157:H7 have been reported from 15 states.
    • Illnesses started on dates ranging from October 5, 2018 to November 18, 2018.
    • Nineteen people have been hospitalized, including two people who developed hemolytic uremic syndrome, a type of kidney failure. No deaths have been reported.
  • The Public Health Agency of Canada has identified ill people infected with the same DNA fingerprint of E. coli O157:H7 bacteria in Canada.
  • Epidemiologic and traceback evidence from the United States and Canada indicates that romaine lettuce harvested from the Central Coastal growing regions of northern and central California is a likely source of the outbreak.
  • Ill people in this outbreak were infected with E. coli bacteria with the same DNA fingerprint as 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 current outbreak is not related to a spring 2018 multistate outbreak of E. coli O157:H7 infections linked to romaine lettuce.
  • CDC is advising that consumers not eat any romaine lettuce harvested from the Central Coastal growing regions of northern and central California. 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 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

December 6, 2018

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

As of December 6, 2018, 52 people infected with the outbreak strain of E. coli O157:H7 have been reported from 15 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 October 5, 2018 to November 18, 2018. Ill people range in age from 1 to 84 years, with a median age of 30. Sixty-nine percent of ill people are female. Of 45 people with information available, 19 (42%) have been hospitalized, including two people who developed hemolytic uremic syndrome, a type of kidney failure. No deaths have been reported.

Illnesses that occurred after November 14, 2018, might not yet be reported due to the time it takes between when a person becomes ill with E. coli infection and when the illness is reported. This takes an average of two to three weeks.

Investigation of the Outbreak

Epidemiologic and traceback evidence indicates that romaine lettuce from the Central Coastal growing regions of northern and central California 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. Twenty-four (83%) of 29 people interviewed reported eating romaine lettuce. This percentage is 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.

Preliminary traceback information from the FDA indicates that ill people in this outbreak ate romaine lettuce harvested from the Central Coastal growing regions of northern and central California. The specific California counties FDA identified in the traceback investigation are Monterey, San Benito, San Luis Obispo, Santa Barbara, Santa Cruz, and Ventura. At this time, no common grower, supplier, distributor, or brand of romaine lettuce has been identified.

The FDA, along with CDC and state partners, is investigating farms and cooling facilities in California that were identified in traceback. CDC collected samples of water to test for E. coli O157:H7; these test results are pending.

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

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