Listeria (Listeriosis)

Listeria monocytogenes (L. monocytogenes) is a species of pathogenic (disease-causing) bacteria that can be found in moist environments, soil, water, decaying vegetation and animals, and can survive and even grow under refrigeration and other food preservation measures. When people eat food contaminated with L. monocytogenes, they may develop a disease called listeriosis.

L. monocytogenes is generally transmitted when food is harvested, processed, prepared, packed, transported or stored in environments contaminated with L. monocytogenes. Environments can be contaminated by raw materials, water, soil, and incoming air. Pets can also spread the bacteria in the home environment if they eat food contaminated with L. monocytogenes.

Symptoms

There are a range of symptoms for listeriosis. Depending on the severity of the illness, symptoms may last from days to several weeks. Mild symptoms may include a fever, muscle aches, nausea, vomiting, and diarrhea. If the more severe form of listeriosis develops, symptoms may include headache, stiff neck, confusion, loss of balance, and convulsions. For the very young, the elderly, and the immune-compromised listeriosis can result in death.

People infected with L. monocytogenes may start to see symptoms in a few hours or as long as two to three days after eating contaminated food. More severe forms of listeriosis may take anywhere from three days to three months to develop.

Due to the range in severity of illness, people should consult their health care provider if they suspect that they have developed symptoms that resemble a(n) L. monocytogenes infection.

At-Risk Groups

The severity of listeriosis varies and in some cases can be fatal, especially among the elderly, people with weakened immune systems or chronic diseases.

Listeriosis can be particularly dangerous for pregnant women and their newborn babies, leading to serious complications with their pregnancy, including miscarriage and stillbirth. Babies born with a listeriosis infection may develop severe health complications that require immediate medical attention, lead to lifelong health problems, or result in death. Women who suspect they have symptoms of listeriosis (muscles aches, nausea, stiffness in neck, headaches, etc.) should seek medical care immediately and tell their health provider what they ate. Learn more about People at Risk of Foodborne Illness.

Foods Linked to U.S. Outbreaks of Listeriosis

Past listeriosis outbreaks in the U.S. have been linked to raw, unpasteurized milks and cheeses, ice cream, raw or processed vegetables, raw or processed fruits, raw or undercooked poultry, sausages, hot dogs, deli meats, and raw or smoked fish and other seafood. L. monocytogenes has also been found in raw pet food.

Preventing Foodborne Illness at Home

The longer ready-to-eat refrigerated foods contaminated with L. monocytogenes are stored in the refrigerator, the more opportunity this pathogen has to grow. To slow down or prevent the growth of L. monocytogenes, set the refrigerator to 40 degrees Fahrenheit (4 degrees Celsius), and the freezer to 0 degrees Fahrenheit (-18 degrees Celsius).

Consumers should also follow these simple steps:

Wash the inside walls and shelves of the refrigerator, cutting boards and countertops, and utensils that may have contacted contaminated foods; 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.
Wipe up spills in the refrigerator immediately and clean the refrigerator regularly.
Wash hands with warm water and soap for at least 20 seconds before and after handling food and following any cleaning and sanitation process.
Pregnant women, the elderly and those with weakened immune systems should avoid certain foods, including unpasteurized or raw milk, cheeses made from unpasteurized milk, raw fish raw sprouts and some other raw foods, which carry a high risk for L. monocytogenes.
People with pets should take special care to avoid cross-contamination when preparing their pet’s food. Be sure to pick up and thoroughly wash food dishes as soon as pets are done eating, and prevent children, the elderly, and any other people with weak immune systems from handling or being exposed to the food or pets that have eaten potentially contaminated food.
Consumers can also submit a voluntarily report, a complaint, or adverse event (illness or serious allergic reaction) related to a food product.

Advice for Restaurants and Retailers

Retailers and/or other food service operators who have handled recalled or other potentially contaminated food in their facilities should:

Contact their local health department and communicate to their customers regarding possible exposure to L. monocytogenes.
To prevent the growth of L. monocytogenes, set the refrigerator to 40 degrees Fahrenheit (4 degrees Celsius), and set the freezer to 0 degrees Fahrenheit (-18 degrees Celsius).
Wash the inside walls and shelves of the refrigerator, cutting boards and countertops, and utensils that may have contacted contaminated foods; 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 and sanitize display cases and surfaces used to potentially store, serve, or prepare potentially contaminated foods.
Wash hands with warm water and soap following the cleaning and sanitation process.
Conduct regular frequent cleaning and sanitizing of cutting boards and utensils used in processing to help minimize the likelihood of cross-contamination.

Unlike most bacteria, L. monocytogenes can grow at refrigeration temperatures and freezing will not eliminate or reduce the pathogen. The FDA recommends that retailers implement time and temperature controls to reduce the opportunity for the growth of L. monocytogenes. L. monocytogenes can also cross-contaminate other food that has been cut and served on the same cutting board or stored in the same area. Retailers should check with your state for specific guidance. More information can be found in the FDA Food Code 2017.

Additional Information

Outbreak of Foodborne Illness

Food Safety for Pregnant Women

Who to Contact

Consumers who have symptoms should contact their health care provider to report their symptoms and receive care.

To report a complaint or adverse event (illness or serious allergic reaction),
visit Industry and Consumer Assistance.