Questions and Answers

Listeriosis is a serious infection caused by the germ Listeria monocytogenes. People usually become ill with listeriosis after eating contaminated food. The disease primarily affects pregnant women, newborns, older adults, and people with weakened immune systems. It’s rare for people in other groups to get sick with Listeria infection.

Listeriosis is usually a mild illness for pregnant women, but it causes severe disease in the fetus or newborn baby. Some people with Listeria infections, most commonly adults 65 years and older and people with weakened immune systems, develop severe infections of the bloodstream (causing sepsis) or brain (causing meningitis or encephalitis). Listeria infections can sometimes affect other parts of the body, including bones, joints, and sites in the chest and abdomen.

Listeriosis can cause a variety of symptoms, depending on the person and the part of the body affected. Listeria can cause fever and diarrhea similar to other foodborne germs, but this type of Listeria infection is rarely diagnosed. Symptoms in people with invasive listeriosis, meaning the bacteria has spread beyond the gut, depend on whether the person is pregnant.

  • Pregnant women: 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 usually diagnosed when a bacterial culture (a type of laboratory test) grows Listeria monocytogenes from a body tissue or fluid, such as blood, spinal fluid, or the placenta.

Listeriosis is treated with antibiotics.

Listeriosis is usually caused by eating food contaminated with Listeria monocytogenes. If infection occurs during pregnancy, Listeria bacteria can spread to the baby through the placenta.

See precautions for people at higher risk of Listeria infection >

You should seek medical care and tell the doctor about eating possibly contaminated food if you have a fever and other symptoms of possible listeriosis, such as fatigue and muscle aches, within two months after eating possibly contaminated food. This is especially important if you are pregnant, age 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 your medical provider if you have questions about what to do after eating possibly contaminated food.

Most people with invasive listeriosis require hospital care, and about one in five people with the infection die. When listeriosis occurs during pregnancy, it can cause miscarriage, stillbirth, or newborn death. Listeriosis during pregnancy results in fetal loss in about 20% and newborn death in about 3% of cases.

Every year, about 1,600 people get listeriosis in the United States.

A few outbreaks of listeriosis 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 >

Find out how recent scientific advances help disease detectives find and solve more listeriosis outbreaks >

Federal, state, and local governments are doing the following:

Find out how CDC and state and federal partners are using real-time whole genome sequencing to solve Listeria outbreaks and make food safer >

People who are more likely to get a Listeria infection (pregnant women, people 65 years or older, and people with a weakened immune system) and those who prepare food for them can:

Everyone can: