Investigation Update: Listeria Outbreak, Meat and Poultry Products, 2024

Key points

CDC and public health officials in several states are investigating a multistate outbreak of Listeria monocytogenes infections linked to recalled Yu Shang Food ready-to-eat meat and poultry products. If you have any of these recalled products in your home, throw them out or return them to the store.

ready-to-eat meat

December 5, 2024

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 show that ready-to-eat meat and poultry products distributed by Yu Shang Food Inc are contaminated with Listeria and are making people sick.

Epidemiologic Data

Since the last update on November 22, 2024, eight new illnesses were reported from five states. These sick people were identified after food and environmental sampling found a second strain of Listeria. As of December 5, 2024, 19 people from eight states have been infected with the outbreak strains of Listeria.

Sick people's samples were collected from October 24, 2021, to October 28, 2024.

  • Of 19 people with information available, 17 (89%) have been hospitalized.
  • Seven illnesses are related to pregnancy.
  • One person who was pregnant was sick and recovered.
  • Two unrelated infants were also sick and recovered.
  • In California, a mother and her twins were sick and both infants died. Listeria was found in a sample from the mother and from one of the twin infants, but it could not be found in a sample from the other infant. Because of this, only the mother and one twin are included as confirmed cases in this outbreak.
  • In Tennessee, a mother and her infant were sick and her infant died.

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 table below has information about sick people in this outbreak (“n” is the number of people with information available for each demographic).

Demographics
Information
Age
(n=19)
Range from <1 to 86 years
Median age of 59
Sex
(n=19)
68% female
32% male
Race
(n=19)
100% Asian
Ethnicity
(n=17)
100% non-Hispanic

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. People reported buying their foods from multiple stores. Among the 14 people interviewed, 11 people shopped in person and online at markets where Yu Shang food products are sold. Among the 13 people asked about precooked chicken products, eight (62%) people reported eating precooked chicken products, and three people (38%) specifically reported eating Yu Shang brand ready-to-eat chicken products.

Laboratory 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 got sick from the same food.

On October 21, 2024, FSIS conducted routine testing and follow-up activities of finished product by Yu Shang Food, Inc. Testing confirmed that the product was contaminated with Listeria. WGS showed that the Listeria in the pork snout product is closely related to bacteria from sick people. This means that people likely got sick from eating foods produced by Yu Shang Food, Inc.

In response to the investigation, FSIS collected additional samples of product produced at Yu Shang Foods, Inc. and from the production environment. The Listeria found in those samples was related by WGS to the bacteria from eight other sick people in the PulseNet database and is different from the strain found in the pork snout sample and the 11 illnesses already included in the outbreak. These illnesses were combined into one investigation.

Public Health Actions

On November 9, 2024, Yu Shang Food, Inc recalled ready-to-eat meat and poultry products. On November 21, 2024, Yu Shang Food, Inc expanded their recall. CDC is advising people not to eat, sell, or serve recalled products.

Previous updates

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 show that ready-to-eat meat and poultry products distributed by Yu Shang Food Inc are contaminated with Listeria and are making people sick.

Epidemiologic Data

As of November 22, 2024, 11 people infected with the outbreak strain of Listeria have been reported from four states. Sick people's samples were collected from October 24, 2021, to July 31, 2024. Of 11 people with information available, nine have been hospitalized. In California, one pregnant person and their twins were sick and both infants died. Listeria was found in a sample from the mother and from one of the twin infants, but it could not be found in a sample from the other infant. Because of this, only the mother and one twin are included as confirmed cases in this outbreak. One other Listeria illness was reported in an infant who was sick and recovered.

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

Demographics
Information
Age
(n=11)
Range from <1 to 86 years
Median age of 64
Sex
(n=11)
55% female
45% male
Race
(n=11)
100% Asian
Ethnicity
(n=11)
100% non-Hispanic

State and local public health officials are interviewing people about the foods they ate in the month before they got sick. People reported buying their foods from multiple stores. Among the eight people interviewed, seven people shopped in person and online at markets where Yu Shang food products are sold. Two people (25%) specifically reported eating Yu Shang brand ready-to-eat chicken products.

Laboratory 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 got sick from the same food.

On October 21, 2024, FSIS conducted routine testing and follow-up activities of finished product by Yu Shang Food, Inc. Testing confirmed that the product was contaminated with Listeria. WGS showed that the Listeria in the pork snout product is closely related to bacteria from sick people. This means that people likely got sick from eating foods produced by Yu Shang Food, Inc.

Public Health Actions

On November 9, 2024, Yu Shang Food, Inc recalled ready-to-eat meat and poultry products. On November 21, 2024, Yu Shang Food, Inc expanded their recall. CDC is advising people not to eat, sell, or serve recalled products.