While most strains of the bacteria Escherichia coli live harmlessly in the intestinal tract of healthy humans, the strain E.coli O157:H7 produces a powerful toxin and can cause severe disease. An infection with E. coli O157:H7 causes severe bloody diarrhea and abdominal cramps. The illness usually occurs within 3 to 5 days after exposure and typically lasts 5 to 10 days. Most persons recover without antibiotics or other treatments. Antidiarrheal agents should NOT be used to treat this infection. In children younger than 5 years and in the elderly, a complication called Hemolytic Uremic Syndrome (HUS) can arise with an E. coli O157:H7 infection. With HUS, red blood cells are destroyed and the kidneys fail. Approximately 2-7% of E. coli O157:H7 infections lead to HUS.

E.coli O157:H7 can be found in the intestines of healthy cattle. Meat can become contaminated during slaughter. Consuming ground beef that has not been sufficiently cooked to kill the bacteria can cause infection. Other vehicles for E. coli O157:H7 infections include the consumption of sprouts, lettuce, salami, unpasteurized milk and juices, and swimming in or drinking of contaminated water. Also the bacteria can be passed from an infected person to another if hygiene or hand-washing practices are inadequate. Some important steps in preventing an E. coli O157:H7 infection include cooking ground beef and hamburgers thoroughly, keeping raw meat separate from ready-to-eat foods, drinking only pasteurized milk, juice, or cider, and washing hands thoroughly with soap and warm water.

Table 1: E. coli O157:H7 Infections in Maryland residents from 1998- 2002

Graph1: 5-year trend E. coli O157:H7 in Maryland residents 1998-2002

Maryland Department of Health and Mental Hygiene
Epidemiology and Disease Control Program
Emerging Infections Program
201 W. Preston St., 3rd Floor
Baltimore, MD 21201
Phone: 410-767-6234
Fax: 410-725-4825
Email: MDEIP@dhmh.state.md.us