In May, days after a group of high school students in the Bay Area nibbled on custard-filled pastries at a catered prom dinner, several of them started to complain about aching stomachs. Around the same time, some college students celebrating their graduation used the same catering company — and also fell ill.
Soon after, more than 350 miles to the south, diners at seven restaurants in Los Angeles, Orange and San Diego counties headed into their doctor's offices with bad bouts of diarrhea.
On June 18, nearly 2,000 miles to the east, in Kenosha, Wis., Tanja Dzinovic finished up a Cobb salad at her favorite restaurant — and less than two days later, she was running a high fever and severely dehydrated from diarrhea. At least 20 other people who ate there also grew ill with salmonella enteritidis.
Local, state and federal epidemiologists tracing back each of these cases — from the fork to the farm — saw one name pop up: Wright County Egg of Galt, Iowa.
Now, with the number of salmonella cases expected to grow and with 380 million eggs recalled, evidence about the cause of the outbreak is pointing toward the farm's owner, which has a history of public health violations.
Federal officials also warned that the number of cases of people who fell sick because of these eggs will probably grow amid the recall — one of the largest of its kind in recent history.
The salmonella outbreak occurred as new FDA egg-safety rules came into effect in early July, which require producers to do more testing for salmonella and take other precautions.
"I will anticipate we will be seeing more illnesses reported," said Dr. Christopher Braden, an acting director at the Centers for Disease Control and Prevention.
From May through July, 1,953 salmonella enteritidis cases were reported, CDC officials say. That number — compared with the 700 cases that have been reported on average in the same time frame of the last five years — alerted federal officials to the seriousness of the outbreak, Braden said.
Early investigations had found cases of people falling ill after eating at 25 restaurants in 10 states.
Braden cautioned that the total number may be difficult to pinpoint, as only 1 in nearly 30 salmonella cases is usually reported to public health authorities. Yet the number of cases known so far is substantial — and growing.
In California, where local and state health officials began aggressively investigating the issue early on, 266 cases have been reported so far.
Some area retailers have been trying to reach out to consumers who bought the recalled eggs: Ralphs supermarkets in Southern California, whose store brand was affected by the recall, is using its store loyalty card database to identify consumers who bought the recalled cartons. The chain is calling those customers to ask them to bring the eggs back for a refund.
Food safety advocates say that salmonella has emerged as a troubling problem in the egg industry, which has become increasingly consolidated with fewer producers controlling a larger swath of the nation's food chain. Salmonella infections can be caused by rodents, flies, birds or other pests that can run through the chicken's feed trough or get inside a farm's feed silo.
"They defecate in the feed, which the chickens then eat and can become infected," said Nancy Bufano, an egg safety rule expert with the Food and Drug Administration. Such infections can spread rapidly and, Bufano added, lead to infected chickens laying infected eggs.
Such contamination can happen on farms both big or small, said food-safety attorney Bill Marler. The U.S. Agriculture Department reportedly estimates that 2.3 million of the nearly 50 billion eggs Americans eat each year are contaminated with salmonella enteritidis.
"The problem is, when you have production on an enormous scale, if something goes wrong, the error gets hugely amplified," Marler said. "If, in this case, you have recalls of eggs that were produced over several months that all got out into the public, there was perhaps something systematically wrong in that facility."
On Wednesday, the Iowa egg producer expanded its initial voluntary recall. The expanded recall — which accounts for less than 1% of the 80 billion eggs produced domestically each year — includes product packed as recently as early this week.
Industry critics say there is growing concern that, while some of the eggs may have been consumed, others may still be in consumers' or restaurants' refrigerators.
Austin "Jack" DeCoster, Wright County Egg's owner, is well-known to agriculture regulators. His various farm operations have been cited for violations of immigration and environmental laws.
One of his operations reportedly paid a $2-million fine to the Occupational Safety and Health Administration for workplace violations. They included unsanitary practices such as workers being told to use their bare hands to remove manure and carcasses.