Listeria is a bacterial illness from eating contaminated food, including raw fish. Its effects are usually higher among pregnant women, newborns, older people and people with weak immune systems. Symptoms include headaches, confusion, stiff neck, and convulsions.
Pregnant women should avoid sushi since the mercury is bad for the fetus and but the listeria is even worse. They may have a miscarriage, have a stillbirth, or may give birth to a baby with serious illness.
Listeria might affect you the day you eat bad fish, or it can evolve up to seventy days later.