Listeriosis is an illness caused by eating foods contaminated with a kind of bacteria, often found in soil and water, called Listeria monocytogenes.
Bacteria are too small to be seen without a microscope.
Most people do not get listeriosis. However, pregnant women and newborns, older adults, and people with weakened immune systems caused by cancer treatments, AIDS, diabetes, kidney disease, etc., are at risk for becoming seriously ill from eating foods that contain Listeria monocytogenes. Listeriosis has flu-like symptoms, such as fever and chills. Sometimes people have an upset stomach, but not always. If the infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur.