HARRISBURG, Pa. -- Pennsylvania State Health Secretary Robert S. Zimmerman Jr. announced that his department and the Philadelphia Department of Health are conducting an investigation into cases of Listeria Monocytogenes that have occurred in July and August in the western and southeastern parts of the Commonwealth. The infection occurs when people eat contaminated food products.
To date, a total of 20 cases have been reported throughout Pennsylvania, seven in Philadelphia residents. Two of the 20 people have died.
"While Listeria can be dangerous for some, most people who are exposed will experience minor, if any, symptoms," Secretary Zimmerman said. "Taking simple, common-sense approaches to food handling and preparation can prevent the spread of the bacteria. These include washing and cooking food thoroughly; keeping uncooked food separate from cooked foods; and washing hands, knives and other food preparation items."
An epidemiological and laboratory investigation into these cases is ongoing. At this time, no specific food product has been identified as a cause for the infections. Laboratory specimens from cases are being collected and forwarded to the Centers for Disease Control and Prevention for further testing.
Referred to as "Listeria," this bacterial infection is an infrequent cause of illness and death in the very young and the very old. It is most frequently contracted through eating contaminated food products. Pregnant women in particular can become infected and spread the infection to their newborns, who then experience severe symptoms such as meningitis.
Listeria bacteria are found in soil and water. Vegetables can become contaminated from the soil or from manure used as fertilizer. Listeria has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter. Unpasteurized (raw) milk or foods made from unpasteurized milk also may contain the bacterium.
Nationally, an estimated 2,500 people become seriously ill with Listeria each year. In Pennsylvania, fewer than two dozen cases are reported in most years. However, Listeria infection only became a reportable disease statewide this year. Now that reporting is mandatory, those numbers may increase in future years.
Investigation of Listeria infection can be difficult because symptoms can surface anywhere from a few days to more than two months after a person eats contaminated food. Fortunately, most people who eat foods containing Listeria bacteria do not become ill.
People who develop Listeria infection may experience a range of symptoms including fever, muscle aches and gastrointestinal symptoms such as nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance or convulsions can occur.
Pregnant women are at increased risk for Listeria infection compared to other healthy adults. About one-third of Listeria cases happen during pregnancy. Infected pregnant women may experience only a mild, flu-like illness; however, infection during pregnancy can lead to premature delivery, infection of the newborn or even stillbirth. There is no routine screening test for susceptibility to Listeria during pregnancy, as there is for rubella and some other congenital infections. Newborns are more likely than their mothers to suffer the serious effects of infection in pregnancy.
People with weakened immune systems, which includes people with AIDS, cancer, diabetes or kidney disease; those who take glucocorticosteroid medications; and the elderly also are susceptible to severe Listeria infections. Individuals with AIDS are almost 300 times more likely to get Listeria infection than people with normal immune systems.
Healthy adults and children occasionally get infected with Listeria, but rarely become seriously ill. Persons experiencing symptoms of the disease should contact their family physician at once.
To reduce your risk for Listeria infection:
-- Cook raw food thoroughly from animal sources, such as beef, pork or
poultry, and wash raw vegetables thoroughly before eating;
-- Keep uncooked meats and vegetables separate from cooked foods and
-- Avoid raw (unpasteurized) milk or foods made from raw milk; and
-- Wash hands, knives and cutting boards after handling uncooked foods.
Recommendations for people at risk of severe infection, such as pregnant women and people with weakened immune systems, in addition to the recommendations listed above, include:
-- Avoid soft cheeses such as feta, Brie, Camembert and blue-veined and
Mexican-style cheese. (Hard cheeses, processed cheeses, cream cheese,
cottage cheese or yogurt are acceptable.);
-- Cook hot left-over foods or ready-to-eat foods, such as hot dogs, until
steaming before consuming; and
-- Although the risk of Listeria infection associated with foods from deli
counters is relatively low, pregnant women and immunosupressed persons
may choose to avoid these foods or thoroughly reheat cold cuts before