The bacteria live in the intestines of some healthy cattle and contamination of the meat may occur in the slaughtering process. Eating meat that is rare or inadequately cooked is the most common way of getting the infection. Fresh vegetables, unpasteurized fruit juices and raw milk have also caused outbreaks. With careless food handling any food product eaten raw can be contaminated by raw meat juices. Contaminated drinking water and swimming in contaminated shallow lakes may also cause infection.
Some infected people have mild diarrhea or no symptoms at all.
Most identified cases develop severe diarrhea and abdominal cramps. Blood is often seen in the stool. Usually little or no fever is present. Symptoms generally appear three to four days after exposure, but can take as long as nine days to appear. Persons experiencing these symptoms should contact their physician.