The Food and Drug Administration has estimated there are about 142,000 cases of salmonella poisoning from eggs each year in the U.S.
And salmonella can spread quickly when eggs are left out at room temperature and not refrigerated.
“A cold egg left out at room temperature can sweat, facilitating the movement of bacteria into the egg and increasing the growth of bacteria,” the USDA states on its website.
Refrigerated eggs should not be left out for more than 2 hours, according to officials.
To further prevent contamination, U.S. egg producers are also required to wash the eggs (right when they're laid and before they're sold to markets) in hot water, then dry and spray them with a chlorine mist.
The spray helps prevent bacteria from getting inside the eggs.
Why do so many countries not refrigerate their eggs?
Constant refrigeration increases shelf life from 21 days to nearly 50 days, so why don’t more countries do it?
According to the New York Times, using the USDA prevention wash approach also gets rid of a thin, protective cuticle on the egg that helps keep moisture inside the egg and bacteria out.
European Union regulations actually prohibit the washing of eggs, because they believe preserving the cuticle is crucial, the New York Times reported.
Additionally, constant refrigeration isn’t always feasible and can be costly.
Don’t Europeans want to prevent salmonella, too?
Of course, but this is where Americans differ from many other countries: Europeans tend to approach salmonella prevention before the eggs are even laid.
Instead, egg-laying hens are often given vaccinations against salmonella. This isn’t required in the U.S.
“They’re different approaches to basically achieve the same result,” Vincent Guyonnet, a poultry veterinarian and former scientific adviser to the International Egg Commission told NPR. “We don’t have massive [food safety] issues on either side of the Atlantic. Both methods seem to work.”
But, he said, staying consistent in approach from the beginning to the time market eggs are sold and consumed is key.
If you buy your eggs chilled, keep them chilled.
Why don’t Americans vaccinate hens?
It’s possible Americans may begin immunization against salmonella more often.
According to a 2014 report from the Los Angeles Times, vaccination has dramatically reduced the number of salmonella cases in the United Kingdom in 20 years.