Further investigation, though, revealed some bigger and unsettling surprises. For starters, the recent salmonella outbreak is not the first one associated with peanut butter. Yes, it is believed to be the first outbreak recorded in the United States, but a similar incident involving peanut butter occurred in Australia in 1996, affecting roughly 50 people.

If that wasn’t surprising enough, West also learned that the U.S. Food and Drug Administration’s Bad Bug Book, considered by many food safety specialists as the definitive source of information about foodborne pathogens, lists peanut butter as an “associated” source of salmonella contamination, not a principal source, such as raw meats, poultry and eggs, but one in which bacteria conceivably could turn up.

In fact, there have been several recent and large outbreaks of salmonella associated with high-fat, reduced water foods such as peanut butter. Based on the findings of one study, published in the Journal of Food Protection in November 2006, researchers speculated that the unique makeup of peanut butter fat mixed with minimal amounts of water can provide adequate conditions for three different salmonella to survive, even despite the intense blasts of heat associated with pasteurization.