Listeriosis Listeria Monocytogenes (A Psychrophilic Bacterium)

What is Listeriosis? Listeriosis is a serious infection caused by eating foods contaminated with the bacterium Listeria Monocytogenes. This disease affects primarily pregnant women, newborn, and adults with weakened immune systems. This bacterium is too small to be seen without a microscope.

Listeria monocytogenes is a rod-shaped aerobic and gram positive pathogenic bacterium that invades the cytoplasm of living cells. It develops a distinctive rocket tail structure to help push through the cytoplasm.  Eventually, these "rockets" push bacteria into neighboring cells, propagating the infection

Symptoms Fever Muscle ache GI Sx: Nausea, diarrhea Pregnant women: mild flu-like Sx, miscarriage, still birth, premature delivery, or infected newborn. Lethargy irritability If infection spreads to the nervous system: headache, stiff neck, confusion, loss of balance, or convulsions. Listeria can cause Pneumonia, Meningitis, and Sepsis.

Contamination Listeria Monocytogenes 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. The bacterium has been found in uncooked meats and vegetables, soft cheeses, deli cold-cuts, and unpasteurized milk or foods. If acquired at birth, the incubation period is 7 to 28 days. The average incubation period is 31 days; with a range from 11 to 47 days.

How do you get Listeriosis? Eating food contaminated with Listeria. Babies can be born with Listeriosis if the mother eats contaminated food during pregnancy. Listeriosis is generally not contagious from person to person.

Diagnosis There is no routine screening test for susceptibility. If you have Sx of fever, or stiff neck, consult your doctor. A blood or spinal fluid test (to cultivate the bacteria) will show if you have Listeriosis. During pregnancy, a blood test is the most reliable way to find out if your Sx are due to Listeriosis.

Prevention Thoroughly cook raw food from animal sources. Was raw vegetables thoroughly before eating. Separate uncooked meats from vegetables, cooked foods and ready-to-eat foods. Avoid unpasteurized milk or food. Wash hands, knives, and cutting boards with hot soapy water for at least 20 sec after handling uncooked foods. Observe all expiration dates on food items. Consume perishable and ready-to-eat foods as soon as possible. Do not eat soft cheeses: feta, brier, camembert, blue-veined, or Mexican-style etc. Do not east refrigerated meat spreads, smoked salmon, smoked seafood; canned or shelf-stable smoked seafood may be eaten. Listeria monocytogenes is killed by cooking or by heating methods, including pasteurization.

Treatment Listeriosis is a serious disease requiring hospitilization. A combination of antibiotics is given intravenously through a small straw-like catheter. When infection occurs during pregnancy, antibiotics must be given promptly to the mother to prevent infection of the fetus or newborn. Babies with Listeriosis receive the same antibiotics as adults. The duration of antibiotic treatment is at least 2 weeks. Even with prompt treatment, some infections result in death.

Statistics About 2,500 people in the U.S develop Listeriosis each year. 5 out of every 100 people carry Listeria Monocytogenes in their intestines. About 20% of people die from the infection. In 1989, there were 1,965 cases of Listeriosis with 481 deaths. In 1993, there were 1,092 cases of Listeriosis with 248 deaths. Listeria Monocytogenes reached the blood and cerebrospinal fluid in 89% of cases. Listeriosis results is a higher number of hospitalizations than any other food-born illness. Pregnant women account for 27% of cases, people with immunodeficiency disorders account for 70% of cases. AIDS patients are 280 time more likely to contract Listeriosis than others.

Government Intervention FDA( Food and Drug Administration) and (FSIS) U.S Department of Agriculture monitor food regularly. FSIS now requires plants that slaughter and process meat and poultry to use a process called (HACCP) Pathogen Reduction and Hazard Analysis and Control Point When a processed food is found to be contaminated, food monitoring and plant inspection are intensified, and if necessary, the implicated food is recalled. NCID( National Center for Infectious Disease is extensively studying Listeriosis to help measure the impact of prevention activities. Early detection and reporting of outbreaks can help identify sources of infection and prevent more cases of the disease.

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