Listeriosis is a disease caused by eating food contaminated with the Listeria monocytogenes bacteria. These bacteria are found in soil, food for horses and cattle, water, mud and silage. They can also live in domestic and wild mammals, fowl and people. The bacteria may pose a risk for illness if soil and manure used as fertilizer contaminate vegetables or if animals contaminate meats and dairy products. The disease may be mild or serious.
Mild illness includes fever and muscle aches and sometimes nausea or diarrhea.
In newborns and adults with weak immune systems, infection may spread to the nervous system or bloodstream and cause sudden fever, intense headache, and stiff neck and confusion, loss of balance, and convulsions. Healthy children and adults may not have any symptoms. If a woman is infected while pregnant, she may not feel very sick, but may have a premature delivery or even lose the baby as a result of infection. A baby can also be infected during the last trimester of pregnancy or during birth, and become ill in the first three weeks of life. The symptoms generally appear about 3 weeks after exposure but may appear as soon as 3 days or as long as 70 days after exposure.