Older persons, pregnant women, infants and anyone with weakened immune systems are especially vulnerable to listeriosis, the illness that can result from listeria infection.
Listeriosis causes 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. The listeria bacteria occurs naturally and is found in the soil and often is carried by animals in their intestines. Although it is readily killed by high temperatures, prepared food can sometimes become infected through careless handling. If you cannot reheat these foods, do not eat them.