Government officials say that the number of people sickened by an outbreak of salmonella poisoning from eggs is likely to rise because officials fear that many of the contaminated eggs are still in peoples' refigerators.
The salmonella outbreak has triggered a massive recall of eggs and sickened about 2,000 people, and many more cases are expected to be reported.
"With the fact that contaminated eggs could still be in consumers' refrigerators, this outbreak could really be one of the largest linked to eggs that we've seen in 20 years," Caroline Smith DeWall of the Center for Science in the Public Interest said.
The number of recalled eggs by an Iowa Farm has skyrocketed to 380 million eggs, up from 228 million eggs on Wednesday. The recall includes eggs that were packed right up until two days ago.
"There are preventative measures that woulld have been in place that could have prevented this if they had been in place more fully," said Sherri McGarry of the FDA's Center for Food Safety and Applied Nutrition.
McCarry said that "one area we are closely looking at and examining" is whether rodents had gotten into the chicken houses. Rodents, she said, "tend to run in the feed troughs.... if they're not well maintained. They defecate in the feed."
The eggs that are believed to be tainted were sold under the following brand names: Lucerne, Mountain Dairy, Sunshine, Hillandale, Trafficanda, Albertson, Farm Fresh, Shoreland, James Farms, Glenview, Mountain Dairy, Ralph's, Boomsma's, Lund, Dutch Farms, Kemps and Pacific Coast.
The eggs are packed in varying sizes of cartons. You can tell if you have a recalled package of eggs by looking at the Julian dates and plant code stamped on the end of the egg carton or on the case label. The Julian dates range from 136 to 229 with plant numbers 1026, 1413, 1942 and 1946.
You can find more information about the recall at the FDA's web site.
Consumers who believe they may have recalled eggs should return them to the store for a full refund, said the company.
Hundreds of people have become sick from eating tainted eggs and one lawsuit has already been filed against the egg supplier, the Wright County Egg Farm in Galt, Iowa.
Wright County Egg announced a voluntary recall of 228 million eggs after they were linked to cases of salmonella poisoning around the country.
Nearly 300 cases of illness in California, Minnesota and Colorado have been linked to the dangerous strain of salmonella, and health officials are now looking for links between the people infected by salmonella poisoning.
Dr. Christopher Braden with the Centers for Disease Control said that illnesses occurring after mid-July may not be reported yet.
"We're seeing a large increase in the number of cases of a particular type of salmonella," said Dr. Chris Braden, a medical epidemiologist at the CDC. "It's pretty much blanketed the nation as far as we know."
Braden said that almost 2,000 cases of salmonella linked with the eggs were reported between May and July. That's 1,300 more than usual for that time of year. During June and July, about 200 cases of the salmonella strain were reported weekly, four times the normal levels.
Some illnesses may not be reported yet because it usually takes at least two weeks from the time someone gets ill before the federal government hears about it.
ABC News senior health and medical editor Dr. Richard Besser said today that while the eggs could have been contaminated at the factory, they could also have gotten the bacteria from the chickens themselves. Investigators are examining whether rodents were pooping in the chicken feed, possibly spreading the salmonella to the eggs.
Besser recommended cooking eggs not included in the recall thoroughly, while authorities investigate the contamination, and eating them immediately aftwerward.
The strain in question, Salmonella enteritidis, is particularly pernicious because it can affect the inside of an egg. The ovaries of a hen can be contaminated by the bacteria, passing the contaminant along to the whites and yoke of an egg as well as outside the shell, Braden said.
"The birds themselves aren't sick. The farmer doesn't even know what's going on. And in the meantime, it's producing eggs that look clean and fine," Braden said.
The federal government says its investigation into the source of the outbreak is ongoing, and while eggs are a prime suspect in many cases, other foods could also be involved. Officials have also not yet determined how salmonella got into the Iowa farm.
Already, one lawsuit has been filed in connection with an outbreak at a Kenosha, Wis. restaurant. A customer says she contracted Salmonella enteritidis there, and she's filed suit against both Wright County Egg and the restaurant, Baker Street Restaurant and Pub in Kenosha.
"Exactly how the salmonella came into the restaurant and whether there were cross-contamination issues in the restaurant or failing to cook within the restaurant, all of that is going to have to be worked out," said Bill Marler, the woman's Seattle-based attorney.
In northern California, officials noticed that dozens of people became sick after eating a certain kind of custard pie. In the southern part of the state, 12 people became ill after attending a catered event.
"It was traced back to the eggs they had consumed," said Dr. Angelo Bellomo of the Los Angeles County Department of Public Health. "At the same time we were doing this, similar incidents were being discovered in other parts of the country."
The U.S. Food and Drug Administration is still investigating the Iowa farm to try to find the source of contamination, though.
"Wright County Egg is fully cooperating with FDA's investigation by undertaking this voluntary recall," the company said in a statement. "Our primary concern is keeping salmonella out of the food supply and away from consumers."
Symptoms of salmonella-related illness could begin as many as three days after eating the eggs, and include fever, cramps and diarrhea, according to Besser. Cooking eggs thoroughly greatly reduces the risk of salmonella poisoning.
Salmonella outbreaks accounted for 142 of the bacterial outbreaks in 2007, including two of the three largest, according to a report from CDC researchers in the Aug. 13 issue of Morbidity and Mortality Weekly Report. The outbreaks included 802 illnesses traced to tainted hummus, and 401 illnesses from frozen pot pies.
Rodents in food packaging and distribution facilities are the most common source of salmonella contamination.
The Associated Press contributed to this report.