Investigation Update: Listeria Outbreak, Meats Sliced at Delis

CDC, public health and regulatory officials in several states, and the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS) are collecting different types of data to investigate a multistate outbreak of Listeria monocytogenes infections.

Epidemiologic, laboratory, and traceback data show that meats sliced at deli counters, including Boar's Head brand liverwurst, are contaminated with Listeria and are making people sick.

Epidemiologic data

Since the last update on August 8, 14 more illnesses and six more deaths have been reported. As of August 27, a total of 57 people infected with the outbreak strain of Listeria have been reported from 18 states. Sick people's samples were collected from May 29, 2024 to August 16, 2024. Of 57 people with information available, all 57 have been hospitalized. One person got sick during their pregnancy and remained pregnant after recovering. Nine deaths have been reported, including one in Illinois, one in New Jersey, one in Virginia, and as of this update one in Florida, one in Tennessee, one in New Mexico, one in New York, and two in South Carolina.

The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because some people recover without medical care and are not tested for Listeria. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.

Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the month before they got sick. This information provides clues to help investigators identify the source of the outbreak.

The list below has information about sick people in this outbreak ("n" is the number of people with information available for each demographic).

• Age (n=57): Range from 32 to 95 years, Median of 77
• Sex (n=57): 51% female, 49% male
• Race (n=52): 75% White, 17% African American/Black, 4% Asian, 4% Other
• Ethnicity (n=48): 94% non-Hispanic, 6% Hispanic

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. People are reporting eating a variety of meats sliced at deli counters. Of the 44 people able to be interviewed, 41 (93%) reported eating deli meats. Thirty-nine of the 41 (95%) reported eating meats sliced at a deli. Of the 41 people who answered if they ate liverwurst, 25 (61%) reported deli-sliced liverwurst before getting sick, and 19 reported Boar's Head brand. These deli meats were sliced at a variety of supermarket and grocery store delis.

Public health actions

CDC advises people to not eat recalled deli meat products. CDC always advises people who are pregnant, aged 65 or older, or have a weakened immune system to avoid eating deli meats or to heat them before consuming.

CDC, public health and regulatory officials in several states, and the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS) are collecting different types of data to investigate a multistate outbreak of Listeria monocytogenes infections.

Epidemiologic, laboratory, and traceback data show that meats sliced at deli counters, including Boar's Head brand liverwurst, are contaminated with Listeria and are making people sick.

Epidemiologic data

Since the last update on July 31, nine more illnesses have been reported. As of August 8, a total of 43 people infected with the outbreak strain of Listeria have been reported from 13 states (seemap). Sick people's samples were collected from May 29, 2024, to July 19, 2024 (seetimeline). Of 43 people with information available, all 43 have been hospitalized. One person got sick during their pregnancy and remained pregnant after recovering. Three deaths have been reported, including one in Illinois, one in New Jersey, and, as of this update, one in Virginia.

The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because some people recover without medical care and are not tested for Listeria. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.

Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the month before they got sick. This information provides clues to help investigators identify the source of the outbreak.

The list below has information about sick people in this outbreak ("n" is the number of people with information available for each demographic).

• Age (n=43): Range from 32 to 94 years, Median of 77

• Sex (n=43): 44% female, 56% male
• Race (n=39): 74% White, 18% African American/Black, 5% Asian, 3% Other
• Ethnicity (n=36): 97% non-Hispanic, 3% Hispanic

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. People are reporting eating a variety of meats sliced at deli counters. Of the 34 people able to be interviewed, 32 (94%) reported eating deli meats. Thirty of the 32 (94%) report meats sliced at a deli – two could not remember if their meats were sliced at the deli. Of the 33 people who answered if they ate liverwurst, 18 (55%) reported deli-sliced liverwurst before getting sick, and 13 reported Boar's Head brand. These deli meats were sliced at a variety of supermarket and grocery store delis.

Laboratory and traceback data

The Maryland Department of Health and Baltimore City Health Department collected an unopened Boar's Head liverwurst product from a retail store and identified Listeria monocytogenes. Additionally, the New York State Food Laboratory identified Listeria monocytogenes from a previously collected sample of unopened Boar's Head liverwurst products collected by the New York State Department of Agriculture and Markets' Division of Food Safety and Inspection from retail stores. WGS determined both to be the same strain as the strain making people sick in this outbreak.

USDA-FSIS conducted traceback of deli meats purchased by sick people in this outbreak to identify producers of interest for further investigation.

Public health actions

CDC advises people to not eat recalled deli meat products. CDC also advises people who are pregnant, aged 65 or older, or have a weakened immune system to avoid eating deli meats or to heat them before consuming.

CDC, public health and regulatory officials in several states, and the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS) are collecting different types of data to investigate a multistate outbreak of Listeria monocytogenes infections.

Epidemiologic and laboratory data now show that meats sliced at deli counters, including Boar's Head brand liverwurst, are contaminated with Listeria and are making people sick.

Epidemiologic data

As of July 26, 2024, a total of 34 people infected with the outbreak strain of Listeria have been reported from 13 states (see map). Sick people's samples were collected from May 29, 2024, to July 12, 2024 (see timeline). Of 33 people with information available, all 33 have been hospitalized. One person got sick during their pregnancy and remained pregnant after recovering. Two deaths have been reported, 1 in Illinois and 1 in New Jersey.

The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because some people recover without medical care and are not tested for Listeria. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.

Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the month before they got sick. This information provides clues to help investigators identify the source of the outbreak.

The list below has information about sick people in this outbreak ("n" is the number of people with information available for each demographic)

• Age (n=34): Range from 32 to 94 years, Median of 74
• Sex (n=34): 44% female, 56% male
• Race (n=31): 78% White, 19% African American/Black, 3% Asian
• Ethnicity (n=29): 97% non-Hispanic, 3% Hispanic

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. People are reporting eating a variety of meats sliced at deli counters. Of the 24 people able to be interviewed, 23 (96%) reported eating meats sliced at a deli. Of the 23 people who answered if they ate liverwurst, 13 (57%) reported deli-sliced liverwurst before getting sick, and seven reported Boar's Head brand. These deli meats were sliced at a variety of supermarket and grocery store delis.

CDC conducted an analysis comparing foods reported by people in this outbreak to foods reported by people who got sick with Listeria but were not part of an outbreak. The analysis showed that people in this outbreak were significantly more likely to eat liverwurst. This information suggests that liverwurst is a likely source of this outbreak. CDC continues to gather information to understand which deli meats are causing illness in this outbreak.

Laboratory and traceback data

The Maryland Department of Health and Baltimore City Health Department collected an unopened Boar's Head liverwurst product from a retail store and identified Listeria monocytogenes. WGS determined it is the same strain as the strain making people sick in this outbreak.

USDA-FSIS conducted traceback of deli meats purchased by sick people in this outbreak to identify producers of interest for further investigation.

Public health actions

On July 30, Boar’s Head expanded their July 26 recall. Do not eat recalled deli meat products. CDC also advises people who are pregnant, aged 65 or older, or have a weakened immune system to avoid eating deli meats or to heat them before consuming.

CDC, public health and regulatory officials in several states, and the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS) are collecting different types of data to investigate a multistate outbreak of Listeria monocytogenes infections.

Epidemiologic information shows that many people in this outbreak report eating meats sliced at deli counters. We do not have information to show that people are getting sick from prepackaged deli meats.

Epidemiologic data

As of July 26, 2024, a total of 34 people infected with the outbreak strain of Listeria have been reported from 13 states (see map). Sick people's samples were collected from May 29, 2024, to July 12, 2024 (see timeline). Of 33 people with information available, all 33 have been hospitalized. One person got sick during their pregnancy and remained pregnant after recovering. Two deaths have been reported, 1 in Illinois and 1 in New Jersey.

The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because some people recover without medical care and are not tested for Listeria. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.

Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the month before they got sick. This information provides clues to help investigators identify the source of the outbreak.

The list below has information about sick people in this outbreak ("n" is the number of people with information available for each demographic).

• Age (n=27): Range from 32 to 94 years, Median of 75
• Sex (n=28): 46% female, 54% male
• Race (n=22): 72% White, 23% African American/Black, 5% Asian
• Ethnicity (n=22): 96% non-Hispanic, 4% Hispanic

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. People are reporting eating a variety of meats sliced at deli counters. Of the 24 people able to be interviewed, 23 (96%) reported eating meats sliced at a deli. Of the 23 people who answered if they ate liverwurst, 13 (57%) reported deli-sliced liverwurst before getting sick, and seven reported Boar's Head brand. These deli meats were sliced at a variety of supermarket and grocery store delis.

CDC conducted an analysis comparing foods reported by people in this outbreak to foods reported by people who got sick with Listeria but were not part of an outbreak. The analysis showed that people in this outbreak were significantly more likely to eat liverwurst. This information suggests that liverwurst is a likely source of this outbreak. CDC continues to gather information to understand which deli meats are causing illness in this outbreak.

Laboratory and traceback data

Maryland Department of Health and Balitmore City Health Department collected an unopened Boar's Head liverwurst product from a retail store and it tested positive for Listeria monocytogenes. WGS is ongoing to determine if the Listeria in the liverwurst is the same strain as the one making people sick in this outbreak.

USDA-FSIS traceback is ongoing to identify the suppliers of deli meats, sliced at deli counters, purchased by people in this outbreak.

Public health actions

On July 26, Boar’s Head recalled liverwurst and other deli products. Do not eat recalled products. CDC also advises people who are pregnant, aged 65 or older, or have a weakened immune system to heat any deli meats before consuming.

CDC, public health and regulatory officials in several states, and the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS) are collecting different types of data to investigate a multistate outbreak of Listeria monocytogenes infections.

Epidemiologic information shows that many people in this outbreak report eating meats sliced at deli counters. We do not have information to show that people are getting sick from prepackaged deli meats.

Epidemiologic data

As of July 19, 2024, a total of 28 people infected with the outbreak strain of Listeria have been reported from 12 states (see map). Sick people's samples were collected from May 29, 2024, to July 5, 2024 (see timeline). Of 28 people with information available, all have been hospitalized. One person got sick during their pregnancy and remained pregnant after recovering. Two deaths have been reported, 1 in Illinois and 1 in New Jersey.

The true number of sick people in this outbreak is likely higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because some people recover without medical care and are not tested for Listeria. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.

Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the month before they got sick. This information provides clues to help investigators identify the source of the outbreak.

The list below has information about sick people in this outbreak ("n" is the number of people with information available for each demographic).

• Age (n=27): Range from 32 to 94 years, Median of 75
• Sex (n=28): 46% female, 54% male
• Race (n=22): 72% White, 23% African American/Black, 5% Asian
• Ethnicity (n=22): 96% non-Hispanic, 4% Hispanic

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. People are reporting eating a variety of meats sliced at deli counters. Of the 18 people able to be interviewed, 16 (89%) reported eating meats sliced at a deli, most commonly deli-sliced turkey, liverwurst, and ham. Meats were sliced at a variety of supermarket and grocery store delis.

CDC conducted an analysis comparing foods reported by people in this outbreak to foods reported by people who got sick with Listeria but were not part of an outbreak. The analysis showed that people in this outbreak were more likely to eat deli-sliced turkey and liverwurst. This information suggests that meats sliced at the deli are a likely source of this outbreak. However, at this time CDC doesn't have enough information to say which deli meats are the source of this outbreak.

Laboratory and traceback data

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).WGS showed that bacteria from sick people's samples are closely related genetically. This suggests that people in this outbreak may have gotten sick from eating this food.

USDA-FSIS is working to identify the suppliers of deli meats, sliced at deli counters, purchased by people in this outbreak.

Public health actions

CDC advises people who are pregnant, aged 65 or older, or have a weakened immune system to contact their healthcare provider if they have any Listeria symptoms. Additionally, CDC advises people to take steps to protect themselves from getting Listeria from deli meats by avoiding eating meats sliced at the deli unless they are heated before eating.