The CDC estimates that 76 million foodborne illness, or food poisoning, cases occur in the United States every year, which means that one in four Americans contracts a foodborne illness annually after eating foods contaminated with such pathogens as E. coli O157:H7, Salmonella, Hepatitis A, Campylobacter, Shigella, Norovirus, and Listeria. Approximately 325,000 people are hospitalized with a diagnosis of food poisoning, and 5,000 die. The estimated costs in terms of medical expenses and lost wages or productivity are between $6.5 and $34.9 billion (Buzby and Roberts, 1997; Mead, et al., 1999).

While most foodborne illness cases go unreported to health departments, nearly 13.8 million food poisoning cases are caused by known agents – 30% by bacteria, 67% by viruses, and 3% parasites (Mead, et al., 1999).

A recent report (2005) released by the CDC in collaboration with the FDA and USDA showed important declines in foodborne infections due to common bacterial pathogens in 2004. From 1996-2004, the incidence of E. coli O157:H7 infections decreased 42 percent. Campylobacter infections decreased 31 percent, Cryptosporidium dropped 40 percent, and Yersinia decreased 45 percent. Salmonella infections dropped 8 percent, but only one of the five most common strains declined significantly. The incidence of Shigella, which is found in a wide variety of foods, did not change significantly from 1996 through 2004. Vibrio infections increased 47 percent. describes seven of the most commonly recognized bacteria and viruses that cause food poisoning. In addition to a general description of each pathogen, we have provided information on the symptoms and risks of each kind of foodborne illness, as well as how they are detected as the cause of infection, and measures you can take to prevent contracting each type of bacterial or viral food poisoning.