The salmonella outbreak of 2008, deconstructed

During the salmonella outbreak of 2008 and 2009 nine people died, 166 were hospitalized and more than 700 fell ill. Authorities ultimately traced the contamination of Salmonella Typhimurium back to a particular company producing peanut products. A study released today in the New England Journal of Medicine details that investigation, highlighting how efforts were sometimes hampered by attempts to trace the food source, and by cracks in the country’s food safety system.

A number of clusters of salmonella cases were found in November 2008 in several states; those exposed to salmonella were asked for food histories to try to determine the origin of the exposure. People mentioned both peanut butter and chicken, and investigators homed in on what types of food were eaten and where they were consumed.

Those products were collected and tested for salmonella, and eventually peanut products were pinpointed as the cause of the outbreak. They were eventually traced to the Peanut Corp. of America, which sold peanut butter to institutional facilities; some of that peanut butter also wound up in commercial products containing peanut butter, such as peanut butter crackers.

Investigations of the company’s facilities found there were several ways salmonella could have contaminated food, including rain and water leaking into storage areas that contained roasted peanuts, possible cross-contamination between raw and roasted peanuts, and potential contact with rodents,. Some peanuts may also not have been roasted at a high enough temperature to kill bacteria.

Eventually the outbreak was specifically linked to eating tainted peanut butter, roasted peanuts and peanut paste made at two PCA locations in Georgia and Texas. The authors noted, “This outbreak resulted in one of the largest food recalls in U.S. history and an estimated $1 billion loss in peanut sales.� The company eventually filed for bankruptcy.

The authors added that because thousands of other food products contained PCA peanut paste and peanut butter, as many as 16 times the reported cases could have occurred.

“This outbreak illustrates the challenge posed by ingredient-driven outbreaks,� they wrote.

But good things came out of the tragedy: The White House Food Safety Working Group was created in 2009 to improve prevention of foodborne diseases, and that launched the FDA’s Reportable Food Registry, an alert system for human and animal food-related issues. This year the Food Safety Modernization Act was signed into law.