The Food and Drug Administration says the salmonella outbreak has affected about 300 people in 39 states since August 2006.
The affected jars of Peter Pan and Great Value peanut butter have a product code number on the lid of the jar that begins with 2111.
Bill Pugliano/Getty Images
A jar of Peter Pan peanut butter with the product code from the lot that has been linked to the salmonella outbreak.
Bill Pugliano/Getty Images
The Centers for Disease Control and Prevention has linked peanut butter to a salmonella outbreak that's sickened almost 300 people since August. No one has died — but dozens of people have been hospitalized.
Investigators have narrowed the search to a plant in Georgia that produces Peter Pan and Great Value brand peanut butter.
When investigators at the CDC and state health agencies first began to notice a trickle of salmonella cases last fall, they were not suspecting peanut butter. The likelier culprits would be eggs or meat.
"Peanut butter, I think, has surprised everybody and certainly was not on the top of our list of suspects," says Dr. Tim Jones of the Tennessee Department of Health. Jones was among the first to document cases of food poisoning in his state; he linked it to a rare type of salmonella.
And he reported the cases to PulseNet, the CDC's electronic tracking system for food borne illnesses.
CDC Investigator.Anandi Sheth says that when similar reports starting coming in from all over the country, the agency decided to interview all the people who'd gotten sick
"We asked them about 200 foods that they ate," Sheth says. "And of those foods, peanut butter stood out as a food that was commonly eaten by the people who were ill."
By the time the CDC conducted enough interviews to name peanut butter as a real suspect, it was already January. People's memories about what they'd eaten months earlier when they got sick were a little shaky.
So investigators like Tim Jones remained a little skeptical.
"Everybody eats peanut butter," Jones said. "It's like saying I eat bread, or drink milk. So really the culprit didn't become clear until we really got down to the level of: what brand?"
This is when investigators asked the people who'd gotten sick to open up their cabinets, to see if the jar of peanut butter they'd eaten back in the fall was still there.
A surprising number of people still had the jars around — and were able to look at the batch numbers on the lids of the jars that tell where the peanut butter was made. This is how investigators narrowed the outbreak to jars of Peter Pan and Great Value brands of peanut butter made at a processing facility in Georgia.
The plant is owned by ConAgra foods, which has now recalled all jars of peanut butter that are labeled with a product code number that begins with 2111.
A spokesman for the company told NPR that every day, plant inspectors randomly pull 60-80 jars of peanut butter and test them for salmonella. The company says they haven't had any positive hits for salmonella since at least 2004.
But food scientists say that doesn't mean that the salmonella wasn't present.
"They're really looking for a needle in a haystack when they're doing this testing after processing," says food scientist Mary Weaver, who manages certifications for the National Sanitation Foundation.
She says an outbreak of salmonella linked to peanut butter may come as a shock to consumers, but it has actually happened once before. Back in 1996 in Australia, an outbreak made 54 people sick. In that case, they were able to figure out where the salmonella came from.
"They implicated the roasted peanuts that were used to make the peanut butter," Weaver says.
The roasting process usually kills off unwanted bacteria. But in this instance, it seems some salmonella cells survived. And Weaver says it doesn't take much to cause sickness.
"In fact, one cell of salmonella could make someone ill. It's a very, very, low infectious rate."
In this new outbreak, it's unclear whether the peanuts were tainted. Another possibility is that the salmonella came through cross-contamination in the plant. The FDA has just begun its investigation.
Tennessee's Tim Jones says the good news is that sickness from salmonella is rarely deadly. It can make people miserable for four or five days — but most people recover fully.