Anyone who has eaten any of the recalled fish is urged to monitor themselves for Listeria infection, which can take up to 70 days to develop. Listeria can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems. Although healthy people may suffer only short-term symptoms such as high fever, severe headache, stiffness, nausea, abdominal pain and diarrhea, listeria infection can cause miscarriages and stillbirths among pregnant women.