A sign warns customers of the recall of certain lots of eggs that had been previously sold at a supermarket in Los Angeles, Thursday, Aug. 19, 2010.
Costco is offering customers a full refund for Hillandale Farms-packaged eggs they've purchased from the store.
The wholesale warehouse last Friday begin calling customers to tell them the stores' eggs may be part of the recall.
About 23 stores in Indiana, Illinois, Wisconsin, and Nebraska have been notified, said Craig Wilson, Costco's Assistant Vice President of Quality Assurance and Food Safety. Stores in California are also affected.
At least 1,000 people have become ill, including one person in the Chicago area, the Chicago Sun-Times reported, but Cook County officials report not getting any calls or reports from people who may have contracted salmonella.
Those who handle eggs should take several precautions, said Dr. Michael Vernon with the Cook County Department of Health, including cooking all eggs or egg-containing meals thoroughly [and] refrigerating eggs until just before use.
"Eating eggs in a sunny side up in a runny fashion is certainly discouraged," he said.
So far, 550 million eggs have been recalled. The eggs are from two separate farms in Iowa: Hillandale Farms and Wright County Egg.