Listeria Monocytogenes

The bacterium Listeria monocytogenes can cause a serious infection called Listeriosis. Symptoms include fever, muscle aches, nausea, and diarrhea. If the disease spreads to the nervous system, it can cause meningitis, a serious infection of the brain and spinal cord whose symptoms include stiff neck, headaches, confusion, loss of balance, and even convulsions. Newborns and very young children, the very old, and people with compromised immune systems are at highest risk for this disease. People with AIDS face a 300-fold greater risk for Listeriosis. Pregnant women who contract Listeriosis usually develop only mild, flu-like symptoms themselves, yet the disease can cause them to miscarry, and can cause premature labor, infection of the fetus, and stillbirth.

The US Centers for Disease Control report that each year about 2500 people become seriously ill with Listeriosis, and for about 500, the disease is fatal. This 25% death rate is strikingly high. By comparison, Salmonellosis is a far more common food borne disease, but its death rate is 1%.

Listeria monocytogenes normally lives in soil, sewage, stream water, and animals. Animals carry the bacteria without getting sick, and it can be transmitted to meat and dairy products. Vegetables can become contaminated from the soil, or from animal manure used as fertilizer. This bacterium has been discovered in uncooked and undercooked meat, cheeses and other dairy products made from unpasteurized milk, and raw vegetables. It is killed by heat.