(AP) -- Two large Iowa farms have recalled 550 million eggs because of possible contamination with salmonella. Investigators from the Food and Drug Administration are trying to find the cause of the outbreak, but so far haven't pinpointed the source.
Q: A half-billion - isn't that a lot of eggs?
A: Well, yes and no. Those 550 million eggs might seem like a lot. But that's less than 1 percent of the roughly 80 billion eggs sold in their shell each year, according to the United Egg Producers, an industry group. Americans consume about 220 million eggs a day, based on industry estimates.
Q: Is the outbreak likely to spread?
A: There's no sign at this point that there are more than the two farms involved, Food and Drug Administration chief Margaret Hamburg said Monday. The recalls started earlier this month when Iowa's Wright County Egg recalled a total of 380 million eggs after some cases of salmonella poisoning were traced back to eggs from its farms. Then last Friday, a second Iowa farm, Hillandale Farms, announced the recall of more than 170 million eggs after tests confirmed salmonella.
Q: Did the eggs get sent to my state?
A: The eggs went to stores or distributors in mostly western or midwestern states, and were shipped nationwide under a variety of brand names. Recalled eggs have a specific plant number and packaged date on the carton; check the FDA website to see if your eggs have been recalled: bit.ly/9yambn
Q: How far back does the recall go?
A: Eggs included in the recall were packaged as far back as four months ago, so it's likely that many of the eggs have already been eaten. If you have any suspect cartons, return them to the store or throw them out.
The Wright County Egg recall extends back to May 15; the Hillandale recall goes back to April 9.
Q: How many people have actually gotten sick?
A: No one knows for sure. Officials say it could be as many as 1,300 so far. The Centers for Disease Control and Prevention saw a spike in illnesses from a specific strain of salmonella in May.
Through the end of July, there were about 2,000 cases - that's about 1,300 more than would be expected for that three-month period. That's where the 1,300 figure comes from, although some of the excess cases may not be tied to this outbreak.
The number is likely to grow since it can take weeks for reports to be filed.
Q: Has anyone died in this outbreak?
A: No deaths have been reported. The most common symptoms of salmonella are diarrhea, abdominal cramps and fever within eight hours to 72 hours of eating a contaminated product. It can be life-threatening, especially to those with weakened immune systems.
Salmonella is the most common form of food poisoning from bacteria, and the strain involved in the outbreak is the most common kind, accounting for about 20 percent of all such food poisonings.
Q: Are the eggs sold at my grocery store safe?
A: Recalled eggs should have been removed from store shelves. But you can check the FDA website bit.ly/9yambn for the brands involved and double-check the egg carton.
Q: Can you tell by looking at the shell or egg if there's salmonella?
A: No, there's no way to tell. But consumers shouldn't buy dirty or cracked eggs.
Q: Then should I just skip eggs to be safe?
A: As long as they're not on the recall list, eggs should be OK. And thoroughly cooking them can kill the bacteria. But while federal investigators continue their work, the FDA's Hamburg said consumers should strictly avoid "runny egg yolks for mopping up with toast."
Q: How do eggs get infected with salmonella?
A: Salmonella bacteria can get on the outside of the shell from fecal matter. Or it can be inside the egg if the chicken is infected. Eggs are washed and disinfected to deal with the dirt and germs on shells, and some producers vaccinate chicks against salmonella.
Infected hens, rodents or tainted feed could be the source of the outbreaks, according to Patrick McDonough, a food safety expert at Cornell University in Ithaca, N.Y. Salmonella is not passed from hen to hen, but usually from rodent droppings to chickens, he said.
The two Iowa farms share suppliers of young chickens and feed. On Monday, an FDA official said the hatchery that supplies the farms has been certified salmonella-free. That suggests that the contamination may have occurred at the farms.
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Egg Safety Center: www.eggsafety.org