Symptoms of E. coli infection
What are the signs and symptoms of illness caused by E. coli O157:H7?
Infection with E. coli O157:H7 can range in severity from causing no symptoms at all (asymptomatic infection), to a mild or modest watery diarrhea only, to severe bloody diarrhea, sometimes including severe complications and death. The classic picture of illness is severe, painful abdominal cramping (so severe that it sometimes gets mistaken for appendicitis) with watery diarrhea that turns bloody within 1 to 3 days. The bloody diarrhea can progress to the point that stools appears to be pure blood. Vomiting can occur as well. Importantly, fever is not a prominent part of illness due to E. coli O157:H7. Less than half of patients ever report a fever, and when they do, it is usually low grade (<101.0oF).
Incubation period is a term that indicates the time it takes from when a person ingests a pathogen (i.e., when they are “exposed”) to when they first develop symptoms of illness. For E. coli O157:H7, the incubation period can range from 1 to 10 days. However, the average incubation period is 3 to 4 days, and incubations from 2 to 6 days are common.
Infection and illness occur in people of all ages. Overall, almost 40% of people with a laboratory-confirmed E. coli O157:H7 infection require hospitalization. Most people will recover within a week or so, but a subset of people become severely ill. Children and people >60 years in age are more likely to develop severe illness, including the life-threatening complication hemolytic uremic syndrome (HUS), which involves kidney failure. However, people of any age can be severely affected.