(AP) -- Food and Drug Administration officials say they have found positive samples of salmonella that link two Iowa farms to a massive egg recall.
Investigators found salmonella in chicken feed at Wright County Egg that was used by that farm and also Hillandale Farms, the FDA said. Authorities also found additional samples of salmonella in other locations at Wright County Egg. More than 550 million eggs from the two farms were recalled this month after they were linked to salmonella poisoning in several states.
One of the positive samples for salmonella was found in a feed ingredient sold to Wright County Egg from a third party supplier, Central Bi-Products, according to Wright County Egg, raising new questions as to whether other egg farms also could have received contaminated feed. The FDA could not confirm that the feed element came from a third party, but so far has said it doesn't believe the salmonella outbreak will expand beyond the two farms.
Also Thursday, the federal Centers for Disease Control and Prevention said there could now be as many as 1,470 illnesses linked to the outbreak, about 200 more than previously thought.
Sherri McGarry of the FDA's Center for Food Safety and Applied Nutrition said the salmonella found at Wright County Egg matches the fingerprint of the salmonella found in many of those who were sickened. She said the tests indicate that contaminated feed is a source of the outbreak but possibly not the only source.
McGarry and other FDA officials emphasized in a briefing for reporters that the agency's investigation is ongoing, and that they do not yet know how the feed became contaminated. Investigators are analyzing as many as 600 samples from 24 locations at the two farms.
Wright County Egg said one of the feed ingredients from Central Bi-Products was held separately in a bin that was tested by FDA officials. Wright County Egg spokeswoman Hinda Mitchell said Central Bi-Products has no ties to the two farms and they receive the feed ingredient, which contains meat and bone meal, from a distributor.
"We will work with FDA as they expand their review of feed ingredients purchased from outside vendors for our farm, as well as for their ongoing review of our farms," said the Wright County Egg statement attributed to unidentified company officials.
FDA spokeswoman Siobhan DeLancey said, "FDA did collect samples of feed ingredients and did identify a salmonella enteritidis positive result from a feed ingredient collected from an unmarked bin. Because the bin was not marked, the agency cannot confirm if the product came from a third-party supplier."
A company listed as Central Bi-Products in Redwood Falls, Minn., that produces "poultry raw material" did not immediately return a call seeking comment Thursday.
Wright County Egg's statement also asserted that a positive environmental test does not mean eggs from that barn would have salmonella. Mitchell said the company had tested some eggs from one of the barns where salmonella was found since July, and those eggs did not test positive for salmonella. The company began testing under new rules put in place for the egg industry this summer to reduce occurrences of the disease.
The feed mill where the salmonella was found operates as part of the Wright County Egg facility and also provides feed to Hillandale Farms. Officials said they are not yet sure whether the feed came to the farm contaminated or was contaminated at the farms. They said there is no evidence at this time that the feed went to any other farms.
FDA Deputy Commissioner Dr. Joshua Sharfstein said the investigators are not just looking at the feed, but at the "overall contamination of the facility." Contamination found in the feed could be a part of a larger problem there, he said.
"While they have found it in the feed they are not confirming any sort of cause and effect relationship," he said.
Congress is hoping to get more answers from the two farms, the FDA and the Agriculture Department in September. A House Energy and Commerce subcommittee announced it will hold a hearing on the recall Sept. 14.
The committee is inviting Austin "Jack" DeCoster, the owner of Wright County Egg, and Orland Bethel, the owner of Hillandale Farms, to testify. The panel is investigating the recall and has written both farms, asking about company operations, communications with the government and what they knew and when.
The panel has also written the FDA, which oversees the safety of shell eggs, and the Agriculture Department, which oversees other egg products and animal disease. The committee asked for records of inspections and past communications with the two farms, along with other documents. The FDA has said it has "no inspectional history" with the two farms.
Rep. Rosa DeLauro, D-Conn., who heads the spending committee that oversees the FDA and USDA, has also written letters to the two agencies.
Mitchell, the Wright County Egg spokeswoman, would not say whether DeCoster will attend the September hearing, but said the company is "working right now" to respond to the committee.
"We will approach it in the same forthright manner as we have in our cooperation with FDA to date," Mitchell said.
DeCoster, who has paid millions of dollars in fines over the last 20 years for health, safety, immigration and environmental violations, has not responded to interview requests.
A worker at his office's headquarters near Galt, Iowa, on Wednesday said he wasn't available, and in his home in Clarion, Iowa, on Wednesday, his wife, Patricia, also said he was not around. She said the last few weeks "have been quite a time for us" but declined further comment.
A spokeswoman for Hillandale Farms also said the company is reviewing the committee's questions and "expect to cooperate in the same open manner as we have with the FDA."
The number of illnesses, which can be life-threatening, especially to those with weakened immune systems, is expected to increase. No deaths have been reported due to this outbreak.
CDC epidemiologist Dr. Christopher Braden said this is the largest outbreak of this strain of salmonella since the start of the agency's surveillance of outbreaks in the late 1970s. The next largest was an outbreak due to raw eggs in ice cream in the 1990s that caused more than 700 illnesses.
Thoroughly cooking eggs can kill the bacteria. But health officials are recommending people throw away or return the recalled eggs.
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More information: Food and Drug Administration: http://tinyurl.com/25ot6ss
Centers for Disease Control and Prevention: http://tinyurl.com/27lla8y
Egg Safety Center industry recall information: http://www.eggsafety.org