What is Listeriosis?

Listeriosis can be a serious infection caused by the bacteria (germs) Listeria monocytogenes. Listeria may infect many different sites of the body, such as the brain or the spinal cord membranes, or the bloodstream. For data on listeriosis in New York City visit EpiQuery.

Who gets listeriosis?

Anyone can get listeriosis, but those at highest risk are newborns, the elderly, people with weakened immune systems, and pregnant women. About 30 percent of cases occur in newborns within the first three weeks of life.

When does Listeriosis occur?

Listeria infections occur throughout the year. Although most cases occur sporadically, foodborne outbreaks do occur.

How is listeriosis spread?

Listeria germs are widely distributed in nature and can be found in water, soil and animals. Foodborne infections are often associated with contaminated vegetables, unpasteurized milk, soft cheeses or ready-to-eat meats. In newborn infections, the organism may be transmitted from mother to fetus in utero, or during delivery.

What are the symptoms of listeriosis?

Because listeriosis can affect many different parts of the body, the symptoms vary. In most cases, Listeria infection causes a nonspecific illness, with fever and influenza-like symptoms. In a more serious form of the infection, known as meningoencephalitis, the onset can be sudden fever, intense headache, nausea, and vomiting.

Are there any unusual features of listeriosis?

Listeria infections are a significant risk for pregnant women, who often do not have symptoms. Infection of the fetus can occur before delivery and can cause abortion as early as the second month of pregnancy, but more often in the fifth and sixth months. An infection later in pregnancy may result in infection of the newborn, which can be fatal.

How soon after infection do symptoms appear?

The symptoms usually appear about 3 weeks after exposure, but can range from 3 to 70 days.

How is listeriosis diagnosed?

If a doctor suspects Listeriosis, he/she can test the spinal fluid, blood, placenta, or other sites of infection to check for the bacteria. Does past infection with Listeria make a person immune? Past infection appears to produce some protective immunity.

What is the treatment for listeriosis?

Several antibiotics are effective for treating listeriosis. Ampicillin, either alone or in combination with other antibiotics, is frequently used.

How can listeriosis be prevented?

Since Listeria is widespread in nature, basic sanitary measures offer the best protection.

Avoid eating uncooked meat and unpasteurized dairy products.

  • Do not eat cheese or dairy products that have not been pasteurized.
  • Make sure meat is thoroughly cooked before eating and/or reheat cold cuts before eating.

Take extra care if you are pregnant or have a weakened immune system.

  • Pregnant women and persons with weakened immune systems may wish to avoid such foods as soft cheeses and raw hot dogs. Although the risk of listeriosis associated with foods from deli counters is relatively low, pregnant women and immunosuppressed persons may choose to avoid these foods or thoroughly reheat cold cuts before eating.

Wash your hands often.

  • Always thoroughly wash your hands with soap and warm running water before touching food, feeding infants, and after handling raw meat.

Last Updated: March 2012