FDA Investigates E. coli O157:H7 Outbreak Likely Linked to Leafy Greens

January 25, 2018

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The U.S. Food and Drug Administration, along with the Centers for Disease Control and Prevention (CDC) and state and local partners, have been investigating an outbreak of E. coli O157:H7 illnesses that were likely linked to leafy greens.

Fast Facts

CDC announced on January 25, 2018, that this outbreak appears to be over, because the last case became ill on December 12, 2017. This indicates that the food causing illness is no longer available in the marketplace or consumers’ homes.
Although this outbreak appears to be over, the FDA’s outbreak investigation team is continuing to work with federal, state and local partners to determine what leafy greens made people ill, what people ate, where they bought it, and identify the distribution chain -- all with the goal of identifying any common food or points where the food might have become contaminated. To date, no common link has been identified.
Because whole genome sequencing showed that the E. coli O157:H7 strain that resulted in the U.S. illnesses was closely related genetically to the strain that caused illnesses in Canada, the FDA and CDC have been in contact with Canadian food safety authorities throughout this outbreak.

What was the Problem and What is being Done About It?

The FDA and the CDC, along with state and local health officials, have been investigating an outbreak of Shiga toxin-producing E. coli O157:H7 infections likely linked to leafy greens. There were 25 cases in 15 states; California (4), Connecticut (2), Illinois (1), Indiana (2), Maryland (3), Michigan (1), Nebraska (1), New Hampshire (2), New Jersey (1), New York (2), Ohio (1), Pennsylvania (2), Vermont (1), Virginia (1), and Washington (1).

Illness onsets were between November 5 and December 12, 2017. Among the 21 ill people for whom CDC has information, nine were hospitalized, including one person in California who died. Two people developed hemolytic uremic syndrome, a type of kidney failure.

Since the outbreak was identified, the FDA has been working with CDC and state and local partners on the investigation. The FDA’s role in outbreaks of this nature is to utilize food consumption information gained from interviews with people who got sick, trace those foods back through the distribution chain to the original source, and attempt to identify the source and route of contamination.

The Public Health Agency of Canada identified romaine lettuce as the source of the outbreak in Canada. In the United States, the likely source of the outbreak appears to be leafy greens, but the investigation has not identified a specific type of leafy greens that sick people ate in common.

The FDA has been in regular contact with Canadian health authorities to share information about the traceback investigation. The FDA’s investigation team has also reviewed information from previous outbreaks to see if there are any commonalities between those and the current outbreak. To date, no common leafy green grower source has been identified.

What are the Symptoms of E. coli O157:H7 Infection?

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 F /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?

Although this outbreak appears to be over, it’s important to know that 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 Do Restaurants and Retailers Need To Do?

Retailers, restaurants, and other food service operators should always take steps to avoid the cross contamination of cutting surfaces and utensils through contact with potentially contaminated products. Retailers, restaurants, and other food service operators should always take steps to adequately control the temperature of cut leafy greens and to avoid cross contamination of cutting surfaces and utensils through contact with potentially contaminated products. To prevent cross contamination, you should follow the steps below:

Wash and sanitize display cases and refrigerators where potentially contaminated products were stored.
Wash and sanitize cutting boards, surfaces, and utensils used to prepare, serve, or store potentially contaminated products.
Wash hands with hot water and soap following the cleaning and sanitation process.
In accordance with the FDA Food Code 2013, cut leafy greens are considered a food requiring time/temperature control for safety and should be refrigerated at 41°F or lower.

Regular frequent cleaning and sanitizing of food contact surfaces and utensils used in food preparation may help to minimize the likelihood of cross-contamination.

What Do Consumers Need To 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.

For refrigerators and other food preparation surfaces and food cutting utensils that may have come in contact with contaminated foods, it is very important that the consumers thoroughly clean these areas and items.

Consumers should follow these simple steps:

Wash the inside walls and shelves of the refrigerator, cutting boards and countertops; then sanitize them with a solution of one tablespoon of chlorine bleach to one gallon of hot water; dry with a clean cloth or paper towel that has not been previously used.
Wash hands with warm water and soap for at least 20 seconds before and after handling food.
Wipe up spills in the refrigerator immediately and clean the refrigerator regularly.
Always wash hands with hot, soapy water following the cleaning and sanitization process.
Persons who think they might have become ill from eating potentially contaminated foods should consult their health care provider.