Q. Why don’t stores in Europe refrigerate eggs?

A. Eggs sold at retail stores in the United States and Europe are handled differently, said Randy W. Worobo, a professor of food science at Cornell University, making the Salmonella risks to consumers different.

Salmonella enteritidis infections from consuming eggs can cause serious illness in susceptible people.

In the United States, the Department of Agriculture requires egg producers to clean and sanitize eggs, Dr. Worobo said. “The washing removes both dirt and fecal matter that might contain salmonella from the exterior,” he said, “but at the same time, it removes a thin outer protective layer.”