Signs and symptoms of E. coli O157:H7 infection usually begin three or four days after exposure to the bacteria. But you may become ill as soon as one day after exposure to more than a week later. Signs and symptoms include: E. coli 
Diarrhea, which may range from mild and watery to severe and bloody
Stomach cramping, pain or tenderness
Nausea and vomiting, in some people
