Symptoms that indicate a listeria infection include diarrhea, nausea, muscle aches and fever, states Mayo Clinic. An infection that has reached the nervous system causes convulsions, balance problems, confusion, stiff neck and headache.
Individuals with a listeria infection typically experience symptoms a few days after consuming contaminated foods; however, symptoms sometimes manifest up to two months after eating the contaminated foods, notes Mayo Clinic. Those who recently ate improperly cooked hot dogs or deli meats, foods made from unpasteurized milk, or other products that are possibly contaminated should see a physician. Light sensitivity, confusion, stiff neck, intense headache and high fever are symptoms of bacterial meningitis, which is a serious complication of a listeria infection.
While a listeria infection causes moderate symptoms in pregnant women, the effects on babies are likely life-threatening, potentially leading to death before birth or severe infection after birth, notes Mayo Clinic. It is crucial to consult a doctor immediately if a pregnant woman experiences symptoms of the infection or if a newborn shows signs such as vomiting, fever, irritability or lack of interest in feeding.
Healthy people are often not vulnerable to listeria infection, but newborns, unborn babies and individuals with weakened immune systems are prone to the sickness, explains Mayo Clinic. Immediate antibiotic treatment is necessary to lower risk of complications.