Questions and Answers
- What are Listeria?
- Can Listeria infection be serious?
- What are the symptoms of infection?
- How is infection diagnosed and treated?
- What should I do if I ate a food that may have been contaminated with Listeria?
- Are outbreaks common?
- What are public health agencies doing to prevent or control Listeria in the U.S. food supply?
- How can I prevent infection?
What are Listeria?
Listeria are bacteria that can contaminate many foods. People who eat those foods can get infected with Listeria. The infection is called listeriosis.
Listeria are most likely to sicken people who are pregnant and their newborns, adults aged 65 or older, and people with weakened immune systems. Other people can be infected with Listeria, but they rarely become seriously ill.
Can Listeria infection be serious?
Yes. CDC estimates that Listeria is the third leading cause of death from foodborne illness in the United States.
Listeria can also cause an intestinal illness that is usually mild. When Listeria bacteria spread beyond the intestines, we call the infection invasive. CDC only tracks Listeria illnesses that are invasive.
Invasive illness in pregnant people is usually mild. However, invasive illness during pregnancy usually leads to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn. Infection during pregnancy results in fetal loss in about 20% of cases and newborn death in about 3% of cases.
Other people with invasive illness – most commonly adults 65 years and older and people with weakened immune systems – usually have infection of the bloodstream (sepsis) or brain (meningitis or encephalitis). Listeria can sometimes infect other parts of the body. Among invasive illnesses not associated with pregnancy, most people need to be hospitalized (about 87% of cases) and about 1 in 6 people die.
What are the symptoms of infection?
Symptoms vary depending on the person infected and the part of the body affected.
CDC’s Listeria symptoms page provides information on the symptoms and severity of both invasive illness and intestinal illness.
How is infection diagnosed and treated?
Infection is usually diagnosed when a laboratory test detects Listeria in body tissue or fluid, such as blood, spinal fluid, or the placenta.
Treatment depends on the kind and severity of a person’s illness. Most Listeria infections are treated with antibiotics. People with diarrhea should drink plenty of fluids.
What should I do if I ate a food that may have been contaminated with Listeria?
Contact a healthcare provider if both of the following things apply to you:
- You ate food that has been recalled or linked to an outbreak.
- You have a fever and other symptoms of listeriosis, such as fatigue and muscle aches.
Let the healthcare provider know if you ate possibly contaminated food. This is especially important if you are pregnant, aged 65 or older, or have a weakened immune system.
If you ate food possibly contaminated with Listeria and do not feel sick, most experts believe you do not need tests or treatment. Talk with a healthcare provider if you have questions about what to do.
Are outbreaks common?
A few outbreaks of Listeria infections are identified most years. Even though most cases of listeriosis are not part of recognized outbreaks, outbreak investigations help show which foods are sources of listeriosis.
- Search NORS Dashboard for information on foodborne disease outbreaks reported to CDC >
- Stay up to date on foodborne outbreaks and food recalls | CDC
- Find out how recent scientific advances help disease detectives find and solve more listeriosis outbreaks >
What are public health agencies doing to prevent or control Listeria in the U.S. food supply?
Federal, state, and local governments are:
- Providing guidance to industry and developing and enforcing regulations, like the Food Safety Modernization Act, to focus food safety efforts on safer production and handling of foods
- Tracking Listeria infections to identify opportunities to improve policies and practices, particularly to protect groups of people who are more likely to get sick with listeriosis
- Investigating and stopping outbreaks by recalling contaminated foods and warning the public
- Applying CDC’s enhanced approach to investigating Listeria infections in all states so disease detectives can rapidly solve outbreaks by:
- DNA fingerprinting the germ to identify outbreaks and contaminated foods, and interviewing people who are sick about what they ate
- Helping health departments get the technology and training for whole genome sequencing and analysis, which will make it possible to find Listeria infections and outbreaks more quickly, and track them to their sources
How can I prevent infection?
People who are more likely to get a Listeria infection and those who prepare food for them should
Everyone can:
