Outbreak of Listeria Infections

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Posted August 23, 2019 at 11:00 AM ET

CDC, several states, and federal partners are investigating a multistate outbreak of Listeria monocytogenes infections. This investigation is ongoing and has not identified a specific food item, grocery store, or restaurant chain as the source of infections. CDC is not recommending that consumers avoid any particular food at this time. Restaurants and retailers are not advised to avoid serving or selling any particular food. We will update our advice if a source is identified.

Latest Outbreak Information
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At A Glance
  • 24 people infected with the outbreak strain of Listeria monocytogenes have been reported from 13 states.
    • Of 23 ill people with information available, 22 hospitalizations have been reported.
    • Two deaths have been reported.
  • A specific food item, grocery store, or restaurant chain has not been identified as the source of infections in the United States.
  • This investigation is ongoing. CDC will provide updates when more information is available.
Advice to Consumers
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CDC is not recommending that consumers avoid any particular food at this time. CDC will update its advice if more information becomes available, such as a supplier or specific food product linked to illness.

Listeria is most likely to sicken pregnant women and their newborns, adults aged 65 or older, and people with weakened immune systems. People who have underlying medical conditions or take medicines (like steroids or chemotherapy) that lower the body’s ability to fight germs and sickness have weakened immune systems.

Some foods are more likely to contain Listeria. People at higher risk for infection should:

  • Heat lunch meats, cold cuts, or other deli meats to an internal temperature of 165°F or until steaming hot just before serving.
  • Avoid eating cold smoked fish, unless it is canned or shelf-stable or it is in a cooked dish, such as a casserole. A food is shelf-stable if it can be safely stored at room temperature.
  • Choose pasteurized milk and milk products, including soft cheese, ice cream, and yogurt.
Symptoms of Listeria Infection
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  • Listeriosis can cause different symptoms, depending on the person and the part of the body affected.
    • Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
    • People other than pregnant women: Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.
  • People with invasive listeriosis usually report symptoms starting 1 to 4 weeks after eating food contaminated with Listeria. Some people have reported symptoms starting as late as 70 days after exposure or as early as the same day of exposure.
  • Listeriosis is treated with antibiotics.
Investigation Details

August 23, 2019

CDC, several states, and federal partners are investigating a multistate outbreak of Listeria monocytogenes infections. This investigation is ongoing and has not identified a specific food item, grocery store, or restaurant chain as the source of infections.

Public health investigators are using the PulseNet system to identify illnesses that may be 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 a standardized laboratory and data analysis method called whole genome sequencing (WGS). CDC PulseNet manages a national database of these sequences that are used to identify possible outbreaks. WGS gives investigators detailed information about the bacteria causing illness. In this investigation, WGS showed that bacteria isolated from ill people were closely related genetically. This means that people in this outbreak are more likely to share a common source of infection.

As of August 23, 2019, a total of 24 people infected with the outbreak strain of Listeria monocytogenes has been reported from 13 states. A list of the states and the number of cases in each can be found on the Map of Reported Cases page.

Listeria specimens were collected from ill people from July 20, 2017, to August 1, 2019. Ill people range in age from 35 to 92 years, with a median age of 72. Sixty-three percent of ill people are female. Of 23 ill people with information available, 22 hospitalizations have been reported. Two deaths have been reported.

The Public Health Agency of Canada is also investigating an outbreak of Listeria monocytogenes infectionsexternal icon in several Canadian provinces linked to cooked diced chicken. Whole genome sequencing showed that the type of Listeria making people sick in Canada is closely related genetically to the Listeria making people sick in the United States.

This investigation is ongoing and a specific food item, grocery store, or restaurant chain has not been identified as the source of infections in the United States. State and local public health officials are interviewing ill people to determine what they ate and other exposures they had before their illness started. CDC will provide more information as it becomes available.