It is hard to know how many people are infected by E. coli O157:H7 each year. Not all cases are documented, and some cases may be misdiagnosed. Furthermore, not all cases of foodborne illness are reported, so it is very difficult to give specific numbers. FoodNet, a database maintained by the CDC, keeps track of 10 states, California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee. Keep in mind this is a probably a low estimate. Extrapolating this rate to the entire population of the U.S., the total number of cases ranges from 3000 to 4000 people per year (1).
Approximately 0-15% of those infected with E. coli O157:H7 will develop a severe side effect called hemolytic uremic syndrome (HUS). The rate of HUS among the same FoodNet population was actually greater than the number of cases of E. coli O157:H7, with between 1.09 and 2.67 cases per 100,000 people per year. HUS can also result from infections of other bacteria, including Shigella, Salmonella, Yersinia and Campylobacter, other common foodborne illnesses (2). The mortality rate for HUS, which primarily affects children under 10, is between 3-7% (3). Among the elderly, HUS has a dire prognosis with mortality rates up to 50% (4).
Sources
1. FoodNet-Foodborne Diseases Active Surveillance Network. 2008. Incidence per 100,000 persons. Online at http://www.cdc.gov/FoodNet/factsandfigures/incidence.html.
2. Mayo Clinic. 2006. Hemolytic uremic syndrome (HUS). Online at http://www.mayoclinic.com/health/hemolytic-uremic-syndrome/DS00876/DSECTION=3
3. Razzaq S, M.D. 2006. Hemolytic uremic syndrome: an emerging health risk. Am Fam Phys. 74:6. Online at www.aafp.org/afp.
4. U.S. Food and Drug Administration. 2007. Escherichia coli O157:H7 from the Bad Bug Book. Center for Food Safety and Applied Nutrition. Online at http://www.cfsan.fda.gov/~mow/chap15.html
