As many as 25 percent of Americans contract a foodborne illness every year, according to the U.S. Centers for Disease Control and Prevention (CDC). Experts estimate that there are 87 million illnesses, 317,000 hospitalizations, and 5,700 deaths a year, with only a small fraction linked to major outbreaks.
Scientists have found more than 250 foodborne illnesses, ranging from parasites to viruses to bacteria. The CDC says that Norwalk-like viruses account for two-thirds of reported food poisoning cases, campylobacter accounts for 14 percent, and Salmonella accounts for 10 percent.
The recent peanut butter salmonella outbreak has lead to over 600 confirmed illnesses in 44 states. Because a case is only confirmed after a lab test is sent to the CDC, health officials assume that the actual number of cases is much higher. In the instance of Salmonella, they estimate that for every reported case there are three dozen that go unreported. According to this calculation, the recent salmonella outbreak could have sickened approximately 20,000 people.