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Outbreak of E. coli Infections Linked to Romaine Lettuce

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Posted December 13, 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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CDC is updating its warning to consumers. It advises that U.S. consumers not eat and retailers and restaurants not serve or sell any romaine lettuce harvested from certain counties in 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.
    • Do not buy, serve, sell, or eat romaine lettuce from the following California counties: Monterey, San Benito, and Santa Barbara.
    • If the romaine lettuce is not labeled with a harvest growing region and county, do not buy, serve, sell, or eat it.
  • Romaine lettuce labeled with a harvest region outside of the three identified counties 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 cannot identify where the romaine lettuce is from, do not buy, serve, eat, or sell it.
  • If you purchased romaine lettuce and do not know where it was harvested, do not eat, serve, or sell it. 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 December 6, an additional 7 ill people have been included in this investigation.
  • Fifty-nine people infected with the outbreak strain of Shiga toxin-producing E. coli O157:H7 have been reported from 15 states and the District of Columbia.
    • Illnesses started on dates ranging from October 5, 2018 to November 16, 2018.
    • Twenty-three 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, laboratory, 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.
  • The FDA, along with CDC and state partners, is investigating 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 Adam Bros. Farming, Inc. farm, which was identified in traceback.
  • CDC is advising that consumers not eat any romaine lettuce harvested from Monterey, San Benito, and Santa Barbara counties in the Central Coastal growing regions of northern and central California. FDA continues its investigation of farms identified in traceback.
  • 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 13, 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 13, 2018, 59 people infected with the outbreak strain of E. coli O157:H7 have been reported from 15 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 5, 2018 to November 16, 2018. Ill people range in age from 1 to 84 years, with a median age of 26. Sixty-five percent of ill people are female. Of 50 people with information available, 23 (46%) 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 21, 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, laboratory, 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-seven (84%) of 32 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. Further information narrowed the number of counties identified in traceback. Based on the evidence available, people should not buy, serve, sell, or eat romaine lettuce from the following California counties: Monterey, San Benito, and Santa Barbara.

The FDA, along with CDC and state partners, is investigating farms and cooling facilities in California that were identified in traceback. CDC analyzed water and sediment samples from Adam Bros. Farming, Inc. farm in Santa Barbara County, California, which was one of the 8 farms identified in traceback. The outbreak strain of E. coli O157:H7 was found in sediment within an agricultural water reservoir located on the farm. Whole genome sequencing 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. 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. Romaine lettuce from Adam Bros. Farming, Inc. farm is no longer available for sale.

FDA’s traceback work suggests that additional romaine shipped from other farms could also be implicated in the outbreak. FDA is continuing its investigation.

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

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