CDC collaborated with public health officials in several states and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Listeria monocytogenes infections (listeriosis). Listeria can cause a serious, life-threatening illness.
Public health investigators used the PulseNet system to identify illnesses that may have been part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA "fingerprinting" is performed on Listeria 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.
A total of 19 people infected with the outbreak strain of Listeria were reported from nine states. A list of states and the number of cases in each can be found on the Case Count Map page.
Listeria specimens were collected from July 5, 2015 to January 31, 2016. Ill people ranged in age from 3 years to 83, and the median age was 64. Of ill people, 74% were female. All 19 (100%) ill people were reported as hospitalized, and 1 person from Michigan died as a result of listeriosis. One of the illnesses reported was in a pregnant woman. WGS was performed on Listeria isolates from all 19 ill people and showed that the isolates were closely related genetically. This close genetic relationship means that people in this outbreak were more likely to share a common source of infection, such as a contaminated food.
According to the Public Health Agency of Canada, ill people in Canada were infected with the same outbreak strain of Listeria. Whole genome sequencing of clinical isolates from ill people in Canada showed that the isolates were closely related genetically to Listeria isolates from ill people in the United States.
Epidemiologic and laboratory evidence indicated that packaged salads produced at the Dole processing facility in Springfield, Ohio and sold under various brand names were the likely source of this outbreak.
State and local health departments interviewed ill people about the foods they may have eaten or other exposures in the month before their illness began. Of 14 ill people who were asked about packaged salad, 13 (93%) reported eating a packaged salad. All of the 9 ill people who specified the brand of packaged salad eaten reported various kinds of Dole brand packaged salad.
As part of a routine product sampling program, the Ohio Department of Agriculture collected a Dole brand Field Greens packaged salad from a retail location and isolated Listeria. This packaged salad was produced at the Springfield, Ohio Dole processing facility. In January 2016, WGS showed that the Listeria isolate from the packaged salad was closely related genetically to isolates from ill people. This information helped link the illnesses to Dole brand packaged salads produced at the Dole processing facility in Springfield, Ohio. Additionally, the Public Health Agency of Canada confirmed the presence of Listeria in packaged salads produced at the Dole Springfield, Ohio processing facility.
On January 21, 2016, Dole reported to CDC that it had stopped production at the processing facility in Springfield, Ohio and withdrew packaged salads from this facility that were on the market at that time. On January 27, 2016, Dole voluntarily recalled all salad mixes produced in the Springfield, Ohio processing facility. The recall included several brands and varieties of salad mixes that were distributed throughout the United States and in Eastern Canada. The type of salad mixes produced at this facility were packaged in bags and plastic clamshell containers and were identified by the letter "A" at the beginning of the manufacturing code on the package. Any recalled salad mixes still on the market or in consumers' homes would be past their expiration dates.
In Canada, there were 14 cases of Listeria monocytogenes in five provinces related to this outbreak: Ontario (9), Quebec (2), New Brunswick (1), Prince Edward Island (1), and Newfoundland and Labrador (1). Individuals became sick between May 2015 and February 2016. The majority of Canadians cases (64%) are female, with an average age of 78 years. All cases have been hospitalized, and three people have died, however it has not been determined if Listeria contributed to the cause of these deaths.
Epidemiologic and laboratory evidence indicate that packaged salads produced at the Dole processing facility in Springfield, Ohio and sold under various brand names are the likely source of this outbreak. Although the investigation began in September 2015, the source of these illnesses wasn’t known until January 2016 when a laboratory result from a packaged salad collected in Ohio linked the illnesses to the Dole processing facility in Springfield, Ohio. On January 27, 2016, Dole recalled all salad mixes produced in the Springfield, Ohio processing facility.
On January 27, 2016, Dole voluntarily recalled all salad mixes produced in the Springfield, Ohio processing facility. At this time, there is no evidence to suggest that any products produced at other Dole processing facilities in the United States are linked to illness. The type of salad mixes produced at this facility was packaged in bags and plastic clamshell containers and can be identified by the letter “A” at the beginning of the manufacturing code on the package.Since September 2015, CDC has been collaborating with public health officials in several states and the FDA to investigate a multistate outbreak of Listeria monocytogenes infections. Twelve people infected with the outbreak strain of Listeria have been reported from six states since July 5, 2015. Twelve people were hospitalized, and one person from Michigan died as a result of listeriosis. One illness was reported in a pregnant woman. Laboratory tests performed on clinical isolates from all 12 ill people showed that the isolates are highly related genetically. Indiana, Massachusetts, Michigan, New Jersey, New York and Pennsylvania state impacted.
Epidemiologic and laboratory evidence available to date indicate that packaged salads produced at the Dole processing facility in Springfield, Ohio and sold under various brand names are the likely source of this outbreak. The Ohio Department of Agriculture collected a Dole brand Field Greens packaged salad from a retail location and isolated Listeria. Laboratory tests showed that the Listeria isolate from the packaged salad was highly related genetically to isolates from ill people. This packaged salad was produced at the Springfield, Ohio Dole processing facility.
Dole Fresh Vegetables, Inc., is temporarily suspending operations at its Springfield, Ohio production facility, and is voluntarily withdrawing from the market all Dole-branded and private label packaged salads processed at that location (see the product list at http://www.cdc.gov/listeria/outbreaks...) Products subject to the voluntary withdrawal are identified with a product code beginning with the letter “A” in the upper right-hand corner of the package (see example below), and are sold in the following states and Canadian provinces noted below. This suspension and withdrawal is being performed voluntarily by Dole out of an abundance of caution, in collaboration with the Food and Drug Administration and Centers for Disease Control. See more about this withdrawal at www.cdc.gov/listeria/outbreaks... No additional Dole facilities are affected. Other Dole products, including fresh fruit, fresh vegetables and packaged salads from Dole’s other processing facilities (with product codes beginning with the letters “B” or “N”), are not part of this voluntary withdrawal.
Retailers and consumers who have any remaining product with an “A” code should not consume it, and are urged to discard it.
Retailers which carry Dole products produced in its Springfield, OH plant (with the product code beginning with the letter “A” in the upper right-hand corner of the package) should check their store shelves and warehouse inventories to confirm that no withdrawn product is available for purchase by consumers. Dole Fresh Vegetables’ customer service representatives have been contacting retailers, and are in the process of confirming that the withdrawn product has been removed from the supply chain.
List of states included in the voluntary withdrawal:
Alabama
Connecticut
Florida
Georgia
Illinois
Indiana
Kentucky
Louisiana
Michigan
Massachusetts
Maryland
Minnesota
Missouri
Mississippi
North Carolina
New Jersey
New York
Ohio
Pennsylvania
South Carolina
Tennessee
Virginia
Wisconsin
List of provinces included in the voluntary withdrawal
Ontario
New Brunswick
Quebec