The outbreak has sickened hundreds of people in 43 states and killed at least six. Earlier this week, it prompted Kellogg to pull some of its venerable Keebler crackers from store shelves, as a precaution.
Although the investigation has gone into high gear, Food and Drug Administration officials say much of their information is still sketchy.
"This is a very active investigation, but we don't yet have the data to provide consumers with specifics about what brands or products they should avoid," said Stephen Sundlof, director of the FDA's food safety center. Although salmonella bacteria has been found at the Georgia plant, for example, more tests are needed to see if it matches the strain that has gotten people sick.
But clearly, what began as an investigation of bulk peanut butter shipped to nursing homes and institutional cafeterias is now much broader.
It includes not just peanut butter, but baked goods and other products that contain peanuts and are sold directly to consumers. Health officials say as many as one-third of the people who got sick did not recall eating peanut butter.
"The focus is on peanut butter and a wide array of products that might have peanut butter in them," said Dr. Robert Tauxe, director of the foodborne illness division at the Centers for Disease Control and Prevention.
Officials said they are focusing on peanut paste, as well as peanut butter, produced at a Blakely, Ga., facility owned by Peanut Corp. of America. The concern about peanut paste is significant because it can be used in dozens of products, from baked goods to cooking sauces.
"It could be a very broad range of peanut-based products here," said Donna Rosenbaum, head of STOP, Safe Tables Our Priority, a consumer group. "We don't know exactly what comes out of this plant. They really don't have their arms around all that."
Federal officials said they are focusing on 32 of the 85 companies that Peanut Corp. supplies, because of the time period in which they received shipments of peanut butter or paste. The companies are being urged to test their products, or pull them from the shelves as Kellogg did.
The government is also scrutinizing a grower, raising the possibility that contamination could have occurred before peanuts reached the processing plant, which passed its last inspection by the Georgia agriculture this summer.
Peanut Corp. has recalled 21 lots of peanut butter made at the plant since July 1 because of possible salmonella contamination. The company, which suspended peanut butter processing at the facility, said none of its peanut butter is sold directly to consumers, but is distributed to institutions, food service industries and private label food companies.
But Kellogg Co., which gets some peanut paste from the Blakely facility, asked stores late Wednesday to stop selling some of its Keebler and Austin peanut butter sandwich crackers. The company said it hasn't received any reports of illnesses.
Peanut Corp. said it is cooperating with federal and state authorities.
"Peanut butter is not supposed to be a risky food," said Patty Lovera, assistant director of Food & Water Watch. "What went wrong? And what does this mean about foods that are considered high-risk, such as raw vegetables?"
Sundlof said salmonella does not thrive in peanut butter, but can remain dormant. Then, when somebody eats the contaminated peanut butter, the bacteria begin to multiply. "That is apparently what happened in this case," he said.
Meanwhile, state health officials on Friday announced that a sixth death has been linked to the outbreak which has sickened more than 450 people in 43 states.
An elderly North Carolina man died in November from the same strain of salmonella that's causing the outbreak, North Carolina health officials said Friday. Tests taken the day before he died indicated the infection had overrun his digestive system and spread to his bloodstream, said Dr. Zack Moore, an epidemiologist with the North Carolina Department of Health and Human Services.
Health officials in Minnesota and Virginia have linked two deaths each to the outbreak and Idaho has reported one. Four of those five were elderly people, and all had salmonella when they died, though their exact causes of death haven't been determined. But the CDC said the salmonella may have contributed.
The family of a 72-year-old Minnesota woman who died says it is pursuing a lawsuit against Peanut Corp. but hasn't yet filed it. The Minnesota Department of Health said Friday that in all, 35 Minnesota residents had been sickened by exposure to the peanut butter, and 13 of those had been hospitalized.
The CDC said the bacteria behind the outbreak - typhimurium - is common and not an unusually dangerous strain but that the elderly or those with weakened immune systems are more at risk.
(Copyright 2009 by The Associated Press. All Rights Reserved.)