Listeriosis

What is listeriosis?

Listeriosis is a disease caused by the bacterium Listeria monocytogenes.

Where are these bacteria found?

L. monocytogenes can frequently be found in the environment, especially in water, mud and silage. It may also be present in the intestines of humans and animals, unpasteurized milk, soil, leafy vegetables and food processing environments.

Outbreaks of listeriosis have been associated with ingestion of unpasteurized milk and milk products made from unpasteurized or inadequately pasteurized milk. Some outbreaks have been associated with raw vegetables or products made with raw vegetables.

Who gets listeriosis?

The greatest risk for disease is among the elderly, immunocompromised persons, or debilitated individuals (e.g. cancer patients). Pregnant women, their fetuses and newborn infants are also at risk for disease.

What are the symptoms?

In adults, the signs and symptoms are influenza-like and include the sudden onset of fever, chills, headache, backache, and occasionally abdominal pain and diarrhea. Newborns may experience respiratory distress, irritability, refusal to drink, and vomiting. Possible complications of the infection include meningitis (inflammation of the tissues around the brain and spine) and septicemia (blood poisoning). During pregnancy listeriosis can cause spontaneous abortions and stillbirths.

How long after exposure do symptoms occur?

During outbreaks, cases have occurred any time between 3 and 70 days after exposure.

How is listeriosis diagnosed?

The diagnosis is confirmed by isolating the bacteria from spinal fluid, blood and other sites of infection. Culturing the stool for L. monocytogenes is not routinely recommended.

How is listeriosis treated?

Specific antibiotics can be prescribed by a physician for the treatment of this illness.

What can be done to prevent listeriosis?

Eat meats that have been properly cooked. Wash fresh vegetables thoroughly. Avoid unpasteurized (raw) milk and cheese or other dairy products made from unpasteurized milk. Pregnant women and other groups at risk are advised to follow "keep refrigerated" labels and observe "sell by" and "use by" dates on processed products. Women who develop influenza-like symptoms during pregnancy should see their physician.

Avoid contact with potentially infected livestock and especially infected animal material such as aborted fetuses.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.