Although the CDC states that pregnant women are 20 times more likely to become infected than non-pregnant healthy adults, the number of cases of listeriosis in pregnant women is about 17% . Symptoms of listeriosis may show up 2-30 days after exposure. Symptoms in pregnant women include mild flu-like symptoms, headaches, muscle aches, fever, nausea, and vomiting. If the infection spreads to the nervous system it can cause stiff neck, disorientation, or convulsions.