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Outbreak Investigation of E. coli O157:H7 Linked to Romaine Lettuce Grown in CA

FDA publishes summary of factors potentially contributing to the Fall 2018 outbreak.

Outbreak Investigation of E. coli O157:H7 Linked to Romaine Lettuce Grown in CA

February 13, 2019

Romaine Lettuce

The FDA has completed its investigation of the multistate outbreak of E. coli O157:H7 illnesses linked to romaine lettuce grown in California in Fall 2018. On February 13, 2019, FDA released an overview of the investigation approach and factors that potentially contributed to the contamination of romaine lettuce with E. coli O157:H7 in this outbreak: Investigation Summary: Factors Potentially Contributing to the Contamination of Romaine Lettuce Implicated in the Fall 2018 Multi-State Outbreak of E. coli O157:H7. This document also provides recommendations to industry for prevention of pathogenic E. coli O157:H7 contamination that is based on the findings outlined in the document.

Additionally, FDA offers the following recommendations to industry to develop and enhance commodity-specific procedures, policies and best practices to enhance the safety of leafy greens:

FDA continues to advise leafy green growers, buyer/shippers, and retailers to develop real-time procedures to quickly explore the possible scope, source(s) and route(s) of contamination when human pathogens of public health significance are detected by routine pre-harvest or finished product verification testing. Local in-depth knowledge and actions are critical in helping determine likely potential routes of contamination of leafy greens in the regions in which they are grown.

Romaine Lettuce on Chopping Board

FDA strongly encourages the entire leafy greens supply chain to adopt traceability best practices and state-of-the-art technology to assure quick, accurate and easy access to key data elements from farm to fork when leafy greens are involved in a potential recall or outbreak.

FDA believes that widespread industry adoption of existing and emerging technologies, that can be used to trace product from the field to the consumer’s kitchen in real time, is critical to protecting the public during a foodborne illness outbreak linked to leafy greens.

Case Counts

Total Illnesses: 62
Hospitalizations: 25
Deaths: 0
Last illness onset: December 4, 2018
States with Cases: CA (12), CT (1), DC (1), FL (1), GA (1), IL (2), LA (1), MA (1), MD (1), MI (7), NH (6), NJ (13), NY (7), OH (1), PA (5), RI (1), WI (1)


What Products are Recalled?

On December 13, 2018, Adam Bros. Farming, Inc., in Santa Barbara County, recalled products products that may have come into contact with water from the water reservoir where the outbreak strain was found. The firm recalled red leaf lettuce, green leaf lettuce and cauliflower harvested on November 27 through 30, 2018. According to the firm, the lettuce and cauliflower was distributed to wholesalers in the U.S. Mexico, and Canada.

The Adam Bros. recall has prompted a recall by Spokane Produce Inc. of Spokane, WA. The firm recalled sandwiches and other products under the Northwest Cuisine Creations and Fresh&Local labels.

What are the Symptoms of E. Coli Infections?

The symptoms of Shiga toxin-producing (STEC) E. coli infections vary for each person but often include severe stomach cramps and bloody diarrhea. If there is fever, it is usually not very high (less than 101 degrees Fahrenheit/less than 38.5 degrees Celsius). Most people get better within 5–7 days. Some infections are very mild, but others are severe or even life-threatening.

Around 5–10 percent of those who are diagnosed with STEC infection develop a potentially life-threatening complication, known as hemolytic uremic syndrome (HUS).

Symptoms of HUS include fever, abdominal pain, feeling very tired, decreased frequency of urination, small unexplained bruises or bleeding, and pallor. Most people with HUS recover within a few weeks, but some suffer permanent damage or die. People who experience these symptoms should seek emergency medical care immediately. Persons with HUS should be hospitalized because their kidneys may stop working (acute renal failure), but they may also develop other serious problems such as hypertension, chronic kidney disease, and neurologic problems.

Who is at Risk?

People of any age can become infected with Shiga toxin-producing (STEC) E. coli. Children under the age of 5 years, adults older than 65, and people with weakened immune systems are more likely than others to develop severe illness, including HUS, but even healthy older children and young adults can become seriously ill.

What Else Should Restaurants and Retailers Do?

Restaurants and retailers should always practice safe food handling and preparation measures. It is recommended that employees wash hands, utensils, and surfaces with hot, soapy water before and after handling food.

  • Regular frequent cleaning and sanitizing of food contact surfaces and utensils used in food preparation may help to minimize the likelihood of cross-contamination.
  • Wash and sanitize display cases and refrigerators regularly.
  • Wash and sanitize cutting boards, surfaces, and utensils used to prepare, serve, or store food.
  • Wash hands with hot water and soap following the cleaning and sanitation process. 

What Else Should Consumers Do?

Consumers should always practice safe food handling and preparation measures. It is recommended that they wash hands, utensils, and surfaces with hot, soapy water before and after handling food. Produce items should be rinsed in clean, running water without the use of cleaners or soaps.

Previous Updates

January 9, 2019

As of January 9, 2019, the CDC reports that the outbreak appears to be over. Contaminated romaine that made people sick in this outbreak should no longer be available on the market. FDA will continue its investigation into potential sources and contributing factors that led to the outbreak in order to inform future prevention efforts.

The Public Health Agency of Canada (PHAC) and Canadian Food Inspection Agency (CFIA) also coordinated with U.S. agencies as they investigated a similar outbreak in Canada. On December 24, PHAC reported that the outbreak in Canada had ended.

December 17, 2018:

On December 13, 2018, Adam Bros. Farming, Inc., in Santa Barbara County, CA, recalled products that may have come into contact with water from the water reservoir where the outbreak strain was found. The firm recalled red leaf lettuce, green leaf lettuce and cauliflower harvested on November 27 through 30, 2018. According to the firm, cauliflower was distributed to wholesalers in the U.S., Mexico, and Canada.

The Adam Bros. recall has prompted a recall by Spokane Produce Inc. of Spokane, WA. The firm recalled sandwiches and other products under the Northwest Cuisine Creations and Fresh&Local labels.

December 13, 2018:

As of December 13, FDA has further refined the traceback investigation down to the farm level, which narrows the list of romaine growing areas that FDA recommends consumers and retailers avoid down to the following counties: Monterey, San Benito, and Santa Barbara.

San Luis Obispo, Santa Cruz and Ventura counties in California have been removed from the list at this time. Other growing areas, for example Florida, Mexico and the desert growing regions near Yuma, Imperial County, and Riverside County do not appear to be related to the current outbreak.

Investigation teams from FDA’s Produce Safety Network, California Department of Public Health, California Department of Food and Agriculture, and the CDC analyzed romaine lettuce, soil, water, sediment, and animal dropping samples at farms identified by the traceback investigation. Most of these samples tested negative for the outbreak strain, with some samples still undergoing analysis. However, the strain of E. coli O157:H7 causing the current outbreak was identified in one sample collected in the sediment of an agricultural water reservoir at one ranch owned and operated by Adam Bros. Farming, Inc., in Santa Barbara County. The strain isolated from this sample matched those collected from ill persons in this outbreak using Whole Genome Sequencing (WGS). FDA is able to confirm that Adam Bros. Farming, Inc. hasn’t shipped any romaine since November 20, 2018. Experts are working with the farm to determine how contamination occurred and what corrective actions need to be taken before their next growing season.

Adams Bros. is cooperating with the FDA and CDC in this outbreak investigation. They have committed to recalling products that may have come into contact with water from the water reservoir where the outbreak strain was found. Produce that did not come into contact with the reservoir water, because it was grown on other ranches within the farm, is not of concern to FDA at this time.

The finding on this farm, however, may not explain all illnesses. The FDA’s traceback activities of romaine lettuce will continue as FDA works to determine what commonalities this farm may have with other farms and areas that are being assessed as part of the investigation.

This information allows FDA to modify its recommendations slightly. Given the identification of the outbreak pathogen on the one farm, the location of farms identified in the traceback, and the fact that the lettuce on the market at the peak of the outbreak should be beyond shelf life, there is no longer a reason for consumers to avoid romaine from San Luis Obispo, Santa Cruz and Ventura Counties, in California.

December 6, 2018:

The FDA continues to conduct a traceback investigation, which involves reviewing shipping records and invoices to trace the romaine that ill people who are part of this outbreak consumed backwards through the supply chain to identify where it was grown and where in the supply chain it may have become contaminated.

Information collected through December 6, 2018, continues to indicate that contaminated romaine lettuce from the Central Coast growing regions of northern and central California is the likely source of the current outbreak of E. coli O157:H7 infections. The California counties FDA is including in this region remain the same: Monterey, San Benito, San Luis Obispo, Santa Barbara, Santa Cruz and Ventura. Counties may be added or removed as the investigation progresses.

Traceback information from four restaurants in three different states so far has implicated 10 different distributors, 12 different growers, and 11 different farms as potential sources of the contaminated lettuce. The information indicates that the outbreak cannot be explained by a single farm, grower, harvester, or distributor.

FDA’s Produce Safety Network (PSN) is assisting with this investigation. The PSN includes regionally-based personnel from FDA’s Center for Food Safety and Applied Nutrition that provide region-specific expertise on produce safety policy and science, and regionally-based personnel from FDA’s Office of Regulatory Affairs that specialize in conducting produce safety inspections and investigations. Members of the PSN work together to support industry and government partners on implementing the Food Safety Modernization Act (FSMA) Produce Safety Rule.

On November 23, 2018, staff from FDA’s Produce Safety Network, investigators from CA Department of Public Health and the CA Department of Food and Agriculture, and CDC began conducting on-site investigations of farms and lettuce cooling facilities in California that have been identified by the FDA, state, and Canadian tracebacks. The investigation teams have been collecting romaine lettuce, soil, water, and scat samples. To date, E. coli O157:H7 has not been found in any of the lettuce, soil or scat samples. Results of water testing being conducted by CDC are pending.

November 30, 2018:

Traceback activities in this romaine lettuce investigation are ongoing and new information continues to be gathered. Analysis of information available through November 30 has not narrowed the potential sources of contaminated romaine lettuce to a specific farm, processor, shipper or distribution center.

November 26, 2018:

The FDA has been conducting a traceback investigation, reviewing shipping records and invoices to trace the supply of romaine from the place where ill people were exposed to the place where that romaine was grown.
Preliminary traceback information indicates that ill people in several areas across the country were exposed to romaine lettuce harvested in California. Specifically, current evidence indicates this romaine was harvested in the Central Coast 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
  • Ventura

Currently, the FDA does not have enough traceback information to identify the source of the contamination that would allow us to request a targeted recall from specific suppliers. On November 20, FDA recommended that the most efficient way to ensure that contaminated romaine is off the market would be for industry to voluntarily withdraw product from the market, and to withhold distribution of romaine until public health authorities can ensure the outbreak is over and/or until FDA can identify a specific source of contamination.

On November 20, the United Fresh Produce Association and the Leafy Greens Marketing Agreement issued statements committing to withdraw the potentially contaminated romaine from the market.

November 20, 2018:

Genetic analysis of the E. coli O157:H7 strains tested to date from patients in this current outbreak are similar to strains of E. coli O157:H7 associated with a previous outbreak from the Fall of 2017 that also affected consumers in both Canada and the U.S. The 2017 outbreak of E. coli O157:H7 was associated with leafy greens in the U.S. and romaine in Canada. This year, romaine lettuce is the suspected vehicle for both the U.S. and Canadian outbreaks. There is no genetic link between the current outbreak and the E.coli O157:H7 outbreak linked to romaine that occurred in the Spring of 2018.

The FDA is conducting a traceback investigation to determine the source of the romaine lettuce eaten by people who became sick. Additionally, FDA and states are conducting laboratory analysis of romaine lettuce samples potentially linked to the outbreak.

Currently, the FDA does not have enough traceback information to identify the source of the contamination that would allow us to request a targeted recall from specific suppliers. At this stage in the investigation, the most efficient way to ensure that contaminated romaine is off the market would be for industry to voluntarily withdraw product from the market, and to withhold distribution of romaine until public health authorities can ensure the outbreak is over and/or until FDA can identify a specific source of contamination. Until then, the FDA advises that consumers should not eat and discard romaine, or any mixed salads containing romaine, until more information on the source of the contamination and the status of the outbreak can be determined.


Who to Contact

Consumers who have symptoms should contact their health care provider to report their symptoms and receive care.

To report a complaint or adverse event (illness or serious allergic reaction), you can

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