Listeria (Listeriosis)
Page originally published 4/2/2026.
Listeriosis is a serious infection caused by eating food with the
bacterium Listeria monocytogenes. Pregnant people, young infants,
older adults, and people with weakened immune systems are at greatest
risk for getting very sick from this infection.
On this page:
- Follow the Clean,
Separate, Cook, and Chill guidelines.
-
Keep the kitchen clean.
- Wash your hands with warm, soapy water before and after handling or preparing food.
- After cooking, use hot, soapy water to wash the utensils, cutting board, and other food preparation surfaces.
- Scrub raw vegetables with a brush under plenty of running water.
- Cook food
completely
- Use a thermometer to make sure meat, poultry, and egg dishes are cooked to a safe temperature.
-
Keep the kitchen clean.
- Stay up to date on foodborne outbreaks and food recalls.
- People at risk and anyone
who prepares food for them should:
- Know the foods more likely to come in contact with Listeria.
- Choose safer food options.
Listeria spread to and from food.
- Places that Listeria can spread include food processing facilities. In the facility, Listeria can spread to food that touches contaminated surfaces or equipment.
- The germs can also grow in food kept in the refrigerator. If we eat food that comes in contact with Listeria, the germs can spread to us and cause a harmful infection.
- Foods that are more likely to be contaminated with Listeria include soft cheeses and raw milk, deli foods and prepared meats, pâte and cold-smoked fish, and sprouts and melons.
When two or more people get the same illness from the same contaminated food or drink, the event is called a foodborne disease outbreak. Learn about active and previous Listeria outbreaks.
Signs and symptoms vary based on the person infected and the part of the body affected.
Listeria can cause intestinal illness. Symptoms may start within 24 hours after eating contaminated food and usually last 1-3 days. Symptoms are usually mild and may include:
- Diarrhea, and/or
- Vomiting.
Some people with intestinal illness may develop invasive illness. Invasive illness happens when Listeria have spread beyond the gut (intestines). Symptoms can be severe and usually start within 2 weeks after eating contaminated food. Symptoms may include:
- Fever;
- Flu-like symptoms, such as muscle aches and fatigue;
- Headache;
- Stiff neck;
- Confusion;
- Loss of balance; and/or
- Seizures.
Invasive illness infection in pregnant people may lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
Listeriosis is usually diagnosed through a blood or spinal fluid test.
Treatment varies based on the severity of illness. Most people recover from illness without treatment, but people that are sick should drink plenty of fluids to prevent dehydration. Antibiotics are needed only for patients who are very ill or at risk of becoming very ill.
County of San Diego
- County of San Diego | County News Center: Dairy Products Recalled for Possible Listeria Contamination (February 20, 2024)
California Department of Public Health (CDPH)
Food and Drug Administration (FDA)
Call the Epidemiology Unit at (619) 692-8499, or send an email, for more information.
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