After reading that patrons of a Baltimore restaurant recently ,, came down with salmonella poisoning after eating foods made with raw eggs, a Sun food writer who savors his holiday eggnog remained unconcerned.
"Only sissies shrink from eggnog," he said, laughing. Then, turning more serious, he noted that the odds of encountering a contaminated egg were vanishingly small, something like 1-in-10,000. So he'll roll the dice and take his chances, and pass the ladle, please.
Chalk one up for food writers: No less an authority than Dr. J. Todd Webber, medical epidemiologist with the federal Centers for Disease Control, confirmed that 1-in-10,000 was as close as scientists could get to calculating the odds.
But there's more to it than that, he insisted. So before sinking your fork into that tangy Caesar salad -- the culprit in the recent restaurant case -- you might want to consider how Dr. Webber processes the available information on raw eggs.
It's true, he said, the odds of buying a contaminated egg -- and then eating it raw or soft-cooked -- are a long shot. But, he pointed out, the real world of restaurants, banquets and household parties complicates the issue far beyond simple odds ratios.
Knowing nothing about specific outbreaks in Baltimore, he made these general observations: "Eggs tend to be pooled, especially in restaurants, institutions and banquets. If you use 100 eggs, all you need is one contaminated egg and you've got problems." The scenario unfolds: Bacteria from one egg infects the entire vat. The nasty bug multiplies like mad. Scores of people get sick.
Removed from the refrigerator, eggs that are cracked, pooled and kept on kitchen counters during food preparation reach room temperatures. This, too, enhances the possibility of bacterial growth.
"Or, say, there's a warming table where hollandaise sauce is kept, that's where it becomes quite hazardous," he said. "People should be aware of the risks so they can decide for themselves. I don't think it's fair to say that when you go into a restaurant, it's luck whether you get sick or not."
Increasingly, raw eggs are being implicated as the source of salmonella poisonings.
Between 1985 and 1989, health departments across the United States reported 244 salmonella outbreaks -- accounting for 8,607 cases of illness, 1,094 hospitalizations and 44 deaths. "Of the 109 outbreaks in which a food vehicle was identified, 89 (82 percent) were associated with shell eggs," said a recent CDC report.
Something new may be happening with eggs.
Until the mid-1980s, most experts believed that the eggshell's surface was the vehicle for transmission. In the henhouse, shells picked up salmonella from feces, hay or other unclean sources. Once this happened, the bacteria could penetrate the shell's pores, or contaminate the innards once the egg was cracked.
Dr. Patrick McDonough, assistant director of microbiology at Cornell University, said the poultry industry has done a good job of washing their eggs and keeping henhouses clean, so infection from the "outside in" should be rare.
But in recent years, experts have found that an infected hen's ovaries can transmit salmonella internally to the developing egg. So the organism lurks inside the egg long before the egg sees the unclean world. Today, most outbreaks have been tied to "inside out" transmission.
It seems, said Dr. McDonough, that hen's didn't always act this way. Most likely, evolution recently gave hens the ability to transmit salmonella internally, but scientists can only guess why it happened.
Equally mysterious is why an infected flock can produce truckloads of clean eggs and then suddenly lay a batch of contaminated eggs capable of sending scores of people to hospitals. One theory is that hens living in overcrowded henhouses are highly susceptible to stress.
"Let's say in the middle of the summer, one of the fans in the poultry house doesn't work, and the birds are too hot," Dr. McDonough said. "There's high humidity. They become immunosuppressed." Suddenly, birds churn out contaminated eggs. Salad fanciers double over in pain.
It's just a theory, he added.
Jimmy Rouse, owner of the popular Louie's Book Store Restaurant in Baltimore's Mount Vernon section, said he stopped serving raw eggs in mid-October as soon as he learned that his Caesar salads had made some people sick. (By the way, it's worth noting that health investigators found nothing wrong with the way food was handled there, just with the raw eggs).
"We served 50,000 Caesar salads over 10 years," he said. "We kept records. We have a computer. But he never heard about anyone getting sick. Until two weeks before Halloween. "We got two cartons of eggs in two weeks that were contaminated. If you get the wrong shipment, it could happen to anybody."
By the way, is spiked egg nog safe? Hardly, said Dr. Webber. Bourbon may be a mild disinfectant, but it's unlikely to turn a bad egg around.