Rendered Proteins Not to Blame for Salmonella Outbreak in Eggs

By Tina Caparella


Since May 2010, the Centers for Disease Control (CDC) has identified a nationwide, four-fold increase in the number of Salmonella enteriditis (SE) isolates and subsequently received reports of approximately 200 SE cases every week during late June and early July. This compares to an average of some 50 reports of SE to the CDC each week over the past five years. Many states have also reported similar increases since May 2010.  

Epidemiologic investigations conducted by public health officials in California, Colorado, and Minnesota revealed several restaurants or events where more than one person fell ill with SE. Information from these investigations suggested that shell eggs were the likely source of infections in many of these restaurants or events.

This led to Wright County Egg of Galt, IA, conducting a nationwide voluntary recall in mid-August of shell eggs that it had shipped since May 19, 2010. Shell eggs from Wright County Egg were sold to distributors and wholesalers in 22 states and Mexico, who then distributed the eggs further throughout the country. On August 13, 2010, Wright County Egg recalled 380 million eggs under many different brand names.

One week later, Hillandale Farms of Iowa initiated an additional recall of eggs that went to grocery stores, distributors, and wholesalers in 14 states; these entities then distributed the eggs further throughout the country. In all, more than 500 million eggs were involved in the nationwide recall, which is less than one percent of eggs produced in the United States.

The Food and Drug Administration (FDA) immediately began an extensive investigation at both Wright County Egg and at Hillandale Farms that involved environmental and product sampling, and records review in order to help identify the source of the contamination. Environmental assessments of farm conditions and practices included pest and rodent controls, biosecurity plans and controls, environmental monitoring, sanitary controls, and feed and laying hen sources. The investigators also looked at commonalities between Wright County Egg and Hillandale Farms.

While the majority of the hundreds of samples FDA collected from Wright County Egg and Hillandale Farms during its investigation were still pending as of press time, the agency reported the following as of late August.

• There were four positive environmental samples that match the DNA fingerprint of the outbreak strain of SE that caused 2,600 people to become ill in 17 states. These were swab samples collected from manure, as well as traffic areas such as walkways, equipment, and other surfaces in and around the facility.

• Two positive samples were collected from the feed mill. The finished feed was provided to pullets raised at Wright County Egg facilities in Iowa. Pullets are distributed to all premises at Wright County Egg and Hillandale Farms. FDA has not found that this feed went to any other companies.

While an egg recall would normally be of little concern to the rendering industry, this recall brought rendered products into the forefront during the investigation, subsequent media briefings, and a congressional hearing. In a late August public statement to a major news organization, Wright County Egg said it 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.” The company went on to say that FDA had tested meat and bone meal on the farm that was provided by third-party suppliers as an ingredient for feed. Wright County Egg stated the ingredient is held separately in an overhead bin that was tested by government officials prior to being mixed with their feed. The company provided FDA with information about the ingredient suppliers, Central Bi Products in Redwood Falls, MN, and a second rendering company in Iowa, and immediately notified both renderers of the testing results.

As of press time, FDA had not identified the definitive source(s) of SE on the farms. Joshua Sharfstein, FDA’s principal deputy commissioner, was quoted in a Des Moines Register news article, “…there was widespread Salmonella contamination on the farm and that there was no reason to believe that the feed ingredient, meat and bone meal, was the source of the bacteria.”

As part of the investigation, the agency examined the storage of the feed and feed ingredients at the farms, feed handling practices on the farms, and other issues, such as origin of the feed ingredients. They are also examining the possibility of contamination of the feed by rodents or birds at the feed mill, whether equipment used to handle manure or bird carcasses is also used to handle feed, and a variety of other potential environmental causes. The feed mill is located within six miles of the various farms, with most of the farms located two miles or less from the feed mill.

On August 30, 2010, FDA issued inspectional observational reports through Wright County Egg and Hillandale Farms. The reports, which are available on the agency’s Web site at www.fda.gov/Safety/Recalls/MajorProductRecalls/ucm223522.htm, list “significant, objectionable conditions” observed by FDA’s investigators, such as failure to prevent stray poultry, wild birds, cats, and other animals from entering poultry houses; bird nests and birds in one poultry house, live rodents in at least one poultry house at several plants, and numerous live and dead flies in poultry houses at certain plants; and failure of employees to change protective clothing when moving from one house to another, and failure to clean and sanitize equipment prior to moving between poultry houses at one plant.

Rendered Products are Safe
Central Bi Products confirmed that FDA did an extensive investigation of its facility, taking over 70 samples to be tested. The company participates in the Animal Protein Producers Industry’s (APPI’s) Salmonella Reduction Education Program to ensure it produces safe feed ingredients. Although official FDA test results were still pending as of press time, Don Davis at Central Bi Products spoke with an investigator on September 20 who indicated the renderer’s retained samples for loads that were shipped to Quality Egg (Wright County Egg) were negative for SE.

“We are pretty confident everything will come back negative for SE,” Davis commented. The rendering company in Iowa was also investigated by FDA with its samples testing negative for SE as well. As of press time, FDA had not publically announced these test results, but did refute statements by Wright County Egg owners in a September 22 congressional hearing that meat and bone meal was the “most likely root cause.”

While rendered products leave the cooker negative of the bacteria, recontamination can occur anywhere along the way to the feed mill or in the feed mill. Renderers take many precautions to prevent recontamination while the meal is in their possession but have little control over their product once it leaves a facility. According to Davis, Quality Egg picked up the load of meat and bone meal August 6, and records show the meal was not delivered until August 9, providing ample opportunity for recontamination.

Established in 1984 as the biosecurity arm of the rendering industry, APPI became a standing committee of the National Renderers Association (NRA) in 2006. Its Salmonella Reduction Education Program involves testing rendered proteins weekly for presence of Salmonella and other bacteria. Participating renderers send samples to an independent laboratory for analysis. Over 95 percent of animal proteins produced in North America are manufactured at facilities that participate in APPI’s Salmonella Reduction Education Program.

The Role of Testing in Rendering
Testing of protein meals for bacteria is used to check the system, not to check every load produced. Renderers also routinely test batches of rendered fats for commonly used pesticides and contaminants before they are released for feed use. Widespread testing of rendered ingredients for the presence of SE is not necessary, cost-efficient, or practical. Research shows SE is not a hazard likely to occur in rendered products. Serotype testing for Salmonella is an expensive procedure that can take up to eight days. Like other feed ingredient suppliers and feed manufacturers, the rendering industry lacks the infrastructure to test and hold for that period of time.

While the positive rate for all Salmonella serotypes is very low, currently at 7.5 percent, renderers continually strive for zero contamination. Many other feed ingredients, including corn and soybean meal, also have a difficult time meeting a zero rate. FDA research shows that many common feed ingredients contain Salmonella, with the overall incidence for all feed, ingredient, and supplement samples (including soybean meal and corn) FDA analyzed in 2007 and 2008 at 5.8 percent.

In an effort to reaffirm the safety of rendered products, NRA, APPI, and Clemson University researchers are in the midst of an APPI-funded year-long study on serovars found in current positive samples of rendered products. While the project is only half complete, an interim summary released in late August showed that among the 7.5 percent of the Salmonella positive samples, the most common foodborne serovars, such as enteriditis or typhimurium, were not detected in the rendered products.

For more information on APPI’s Salmonella research in rendered products, see “ACREC Solutions” in this issue of Render.


Newsline – October 2010 RENDER | back