Fever is not always present, and develops with the first symptoms between 1 to 10 days after exposure to pathogenic E. Coli strains. Even when present the fever is mild. A sudden increase in body temperature followed by other worsening symptoms may suggest that the bacteria have reached the bloodstream; a condition known as septicemia. If treated timely this is not dangerous, but if left untreated it can cause sepsis and possible death. Luckily, lethal cases are rare these days, as adequate antibiotics and diagnostic tools are widely available.