The list ranges from goodies like cookies and ice cream to energy bars. Even food for pooches may not be entirely safe, with a national company recalling some of its dog treats.
On Tuesday, PetSmart recalled seven kinds of its Grreat Choice dog biscuits. On Wednesday, the weight loss company NutriSystem issued a recall for peanut butter granola bars. And some Asian foods made with peanut sauces are starting to turn up on the recalls list.
To help consumers, the Food and Drug Administration has set up on its Web site a searchable database of recalled peanut products. "We expect (the) number to continue to increase," said Stephen Sundlof, head of the FDA's food safety program. No major brands of peanut butter sold in jars are implicated.
Peanut butter is not normally thought of as a high-risk product for salmonella. The bacteria, a frequent source of food poisoning, is supposed to be killed off in the roasting process.
In this investigation, the common denominator is that all the products contain peanut paste or peanut butter made at a Peanut Corp. of America plant in Blakely, Ga.
Originally the problem appeared limited to peanut butter shipped in big tubs to institutional customers like nursing homes. But then peanut paste was implicated. Made from ground roasted peanuts, it is used as an ingredient in dozens of other products sold directly to consumers.
Last week, Kellogg recalled some of its Austin and Keebler brand peanut butter crackers. Salmonella was later confirmed in a package of Austin crackers.
At least 486 people in more than 40 states have gotten sick since the outbreak began in the fall. Six have died.
Investigators found salmonella contamination at the PCA plant, which has suspended production. In one of the curious twists in the investigation, the salmonella strain at the plant is not an exact match to the one that has gotten people sick, the FDA said. However, the outbreak strain has been positively identified in a sample from an unopened jar of peanut produced at the Georgia plant.
Sundlof suggested it doesn't much matter whether health authorities get a perfect match at the plant. "Having salmonella in the plant is not supposed to happen," he said. "Regardless of whether it's the outbreak strain or not, that represents a violation."
Salmonella has been found in a floor crack and on the floor near a wall where pallets are stored, he said.
The manufacturer said it is cooperating with the investigation, but has received nothing in writing from health investigators to document their findings. "We trust that at some point they will share this with us and PCA will respond accordingly," said a company statement.
Although PCA is a small company, it lists more than 70 food companies as its customers. "Peanut paste is used in a huge variety of other foods," said Dr. Robert Tauxe, who is directing the investigation for the Centers for Disease Control and Prevention.
A noted food safety scientist said manufacturers have to be careful that peanuts don't get contaminated after roasting. That's partly because peanut butter itself can't be heated to kill the bacteria without making it unpalatable to eat.
"Once the salmonella gets into the peanut butter, you are not going to kill it," said Michael Doyle, head of the University of Georgia's food safety center. "What the processor has to rely on is the roasting process. That's a critical control point."
After roasting, peanuts can be contaminated if they somehow come into contact with tainted water, or if birds or rodents get into the plant. They can also be cross-contaminated by equipment that is used to handle raw ingredients. Raw peanuts can harbor salmonella, just like other agricultural products.
"If there are fork lifts in the raw ingredient area, they can't go into the other part of the plant, because they could be bringing in untreated material," Doyle said. Federal and state officials would not discuss details of the investigation at the Georgia plant.
The FDA's Sundlof said it's rare for dogs to get salmonella illness, but that their owners can pick up the bacteria by handling tainted biscuits. If people don't wash their hands after feeding the dog, they can transfer the bacteria to human foods.