WASHINGTON — Food and Drug Administration officials said Thursday that their investigators have honed in on chicken feed as a likely major contributor to the salmonella contamination that triggered a nationwide egg recall and potentially caused nearly 1,500 cases of illness.
Feed found at Wright County Egg in Iowa tested positive for salmonella, FDA officials said at a joint news conference with the Centers for Disease Control and Prevention. Salmonella also was found in walkways and manure at Wright County Egg, as well as in ingredients used in the feed. The samples of the salmonella were a genetic match to the salmonella that has made many people sick, officials said.
The feed also was given to young hens, called pullets, that were supplied to Hillandale Farms, also in Iowa.
"The finding of positive feed raises a lot of additional questions for us to answer," said Jeff Farrar, the FDA's associate commissioner for food protection. "We don't have all those answers, but we're working hard."
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Investigators took about 600 samples from 24 locations as part of their investigation of the two farms, which produced more than 550 million eggs that were recalled after a spike in salmonella cases.
While the chicken feed has emerged as one likely source of contamination, other sources may emerge because the testing has not been completed, said Sherri McGarry, an emergency coordinator for the FDA.
Investigators stressed that the exact cause of the contamination still has not been determined. The salmonella samples found in the feed could signal a larger problem of site contamination, said FDA Deputy Commissioner Joshua Sharfstein.
"There is evidence of contamination at the farm. While they have found it in feed, they are not concluding any cause-and-effect relationship," he said. "There are multiple potential routes of contamination. Our focus is really not on the feed but the overall recontamination of the facility."