August 4, 2005
City of Albuquerque
Listeriosis is a serious infection caused by eating food contaminated with the bacterium Listeria monocytogenes and it has recently been recognized as an important public health problem in the United States. The disease affects primarily pregnant women, newborns and adults with weakened immune systems. This pathogen causes nearly 2,500 cases of listeriosis per year in the United States. Of these, 500 died.
Those at increased risk are:
Pregnant women — They are about 20 times more likely than other healthy adults to get listeriosis. About one-third of listeriosis cases happen during pregnancy.
Newborns — Newborns rather than the pregnant women themselves suffer the serious effects of infection in pregnancy.
Persons with weakened immune systems.
Persons with cancer, diabetes, or kidney disease.
Persons with AIDS — They are almost 300 times more likely to get listeriosis than people with normal immune systems.
Persons who take glucocorticosteroid medications (cortisone).
The elderly. Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill.
What are the Symptoms?
A person with listeriosis has fever, muscle aches, and sometimes 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.
Infected pregnant women may experience only mild, flu-like illnesses; however, infections during pregnancy can lead to miscarriage or stillbirth, premature delivery, or infection of the newborn.
How is it Transmitted?
Listeria prefers cold and/or wet places including refrigeration and air handling systems; it thrives in dairy products including soft cheeses, deli meats, hot dogs and food processing plants. Listeria is found in soil and water. Vegetables can become contaminated from the soil or from manure used as fertilizer. Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin such as meats and dairy products. Listeria has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed food that become contaminated after processing, such as cold cuts at the deli counter. Unpasteurized (raw) milk or foods made from unpasteurized milk may contain the bacterium.
Pasteurization and cooking kills Listeria; However, in certain ready-to-eat foods such as hot dogs and deli meats, contamination may occur after cooking but before packaging.
Which Foods Might Contain Listeria?
Listeria has been found in the following foods: raw milk, supposedly pasteurized fluid milk, cheeses (particularly soft ripened varieties), ice cream, raw vegetable, fermented raw meat sausages, raw and cooked poultry, raw meats (all types), and has also been found in, raw and smoked fish.
If I’m Infected, How Long Before I Get Sick?
The incubation period varies; symptoms might occur 3-70 days following a single exposure to an implicated product. The estimated average incubation is 3 weeks.
How Do I Avoid Listeria?
Thoroughly cook raw food from animal sources, such as beef, pork or poultry.
Separate raw meat, poultry, and seafood from vegetables and cooked or ready-to-eat foods.
Wash hands, knives and cutting boards after handling raw foods.
Wash uncooked vegetables thoroughly before eating.
Do not drink unpasteurized (raw) milk.
Refrigerate perishable items that are precooked or ready-to-eat at 40F or below and consume as soon as possible or freeze — ìWhen in doubt, throw it out”.