Listeria monocytogenes is a rod shaped bacterium that can cause severe and sometimes fatal illness primarily in pregnant women, newborns and adults with compromised immune systems. Persons with a Listeria infection experience fever, muscle aches, and at times gastrointestinal symptoms such as nausea or diarrhea. The incubation period for Listeria can be variable, although most signs and symptoms appear approximately 4 weeks after exposure. Antibiotics are used to treat Listeria infections. Listeria monocytogenes can be found in soil, water and in some animals. Listeria monocytogenes has been found in a variety of raw foods like uncooked meats and vegetables, as well as ready-to-eat foods that become contaminated after processing such as soft cheeses and deli counter cold cuts. Listeria has also been found in unpasteurized milk and foods made from unpasteurized milk. The risk of acquiring a Listeria monocytogenes infection, especially those populations at greater risk, can be reduced by thoroughly cooking raw foods of animal origin, washing vegetables, keeping uncooked meats separate from vegetables, cooked foods, and ready-to-eat foods, and avoiding unpasteurized milk and foods made using unpasteurized milk.

Table1: Listeria monocytogenes in Maryland Residents 1998-2002

Graph1: Listeria monocytogenes in Maryland Residents: 5 year Incidence Trend