An epidemiologic study showed that consumption of Peter Pan peanut butter and Great Value peanut butter were both statistically significantly associated with illness and therefore the likely source of the outbreak. Product testing confirmed the presence of the outbreak strain of Salmonella Tennessee in opened jars of peanut butter obtained from ill persons.
As of May 22, 2007, 628 persons infected with the outbreak strain of Salmonella Tennessee had been reported to CDC from 47 states. Among 481 patients for whom clinical information was available, 21% were hospitalized. No deaths were attributed to the outbreak. Illness onset dates ranged from August 1, 2006 to April 23, 2007.
On April 5, 2007, ConAgra announced that its own investigation found that moisture might have triggered the growth of the Salmonella bacteria. Inadvertent moisture in the company's Sylvester, Georgia, production facility could have allowed the growth of dormant Salmonella organisms that were likely present in raw peanuts or peanut dust, ConAgra stated in a press release. A ConAgra spokesperson stated that the moisture came from a roof that leaked during a rainstorm and from a faulty sprinkler system that went off twice during August 2006.