Raw egg

Uncooked, unpasteurized egg. Salmonella enteritidis, a harmful bacterium, can be transmitted from infected hens directly to the interior of their eggs before the shells are formed. Even eggs with clean, uncracked shells can be infected. The CDC (Centers for Disease Control and Prevention) now estimate that 1 egg in 20,000 may be contaminated. Although the number of eggs affected is quite small, there have been a number of cases of foodborne illness related to infected eggs.

A person infected with Salmonella enteritidis usually has fever, abdominal cramps, and diarrhea beginning 12 to 72 hours after consuming the contaminated egg. The illness usually lasts 4 to 7 days. Although most people recover fully, the diarrhea may require hospitalization. The elderly, infants, and those with impaired immune systems may have a more severe illness. In them, the infection may spread from the intestines to the blood stream, and then to other body sites and cause death unless the infection is treated promptly with antibiotics.

If eggs are thoroughly cooked, the Salmonella are destroyed. Many dishes made in restaurants or commercial or institutional kitchens, however, are made from pooled eggs. If 500 eggs are pooled, one batch in 20 will be contaminated and everyone who eats eggs from that batch is at risk.

Shell eggs are safest when stored in the refrigerator, individually and thoroughly cooked, and promptly consumed. The larger the number of Salmonella present in the egg, the more likely it is to cause illness. Keeping eggs well refrigerated prevents any Salmonella present in the eggs from growing to higher numbers, so eggs should be held refrigerated until they are needed.

Cooking reduces the number of bacteria present in an egg. Undercooked egg whites and yolks have been associated with outbreaks of Salmonella enteritidis infections. Both should be consumed promptly and not be held in the temperature range of 40 to 140 degrees F for more than 2 hours, according to the CDC.

The CDC also recommends discarding cracked or dirty eggs; washing hands and cooking utensils with soap and water after contact with raw eggs; avoiding eating raw eggs as in homemade ice cream or eggnog; and avoiding restaurant dishes made with raw or undercooked unpasteurized eggs. (Knowing whether a restaurant has used raw eggs may not be easy.)