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Frequently Asked Questions & Answers: FDA's Investigation into the Salmonella Enteritidis Outbreak Involving the Recall of Shell Eggs

Below is information related to the Salmonella Enteritidis Outbreak in Shell Eggs - May 2010.

Updated August 27, 2010

Q: How many samples has FDA collected and what are the results?

A: FDA has collected hundreds of samples from Wright County Egg and Hillandale Farms Inc. of Iowa during this investigation. The majority are still pending.

We have reported the following:

4 positive environmental samples that match the DNA fingerprint of the outbreak strain of Salmonella Enteritidis. These were swab samples collected from manure, as well as traffic areas such as walkways, equipment, other surfaces in and around the facility

2 positive samples 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 in Iowa and Hillandale Farms in Iowa.

In reviewing records as part of our investigation, FDA has not found that this feed went to any companies other than Wright County Egg and Hillandale Farms of Iowa.

Q: What does this mean in terms of the investigation?

A: These positive samples, along with the DNA fingerprint (also known as pulsed-field gel electrophoresis [PFGE), indistinguishable from the outbreak strain, indicate that Wright County Egg and Hillandale Farms of Iowa are the likely sources of the contaminated shell eggs.

A positive finding of SE in the feed or feed ingredient intended for poultry would mean that the feed is adulterated.  

This is part of the overall, ongoing investigation of the operations that can help us understand the cause of this contamination.   

Q: What are FDA’s next steps in its investigation of the feed?

A: It is not known at this time how the feed became contaminated. Some of the factors include examining the storage of the feed and feed ingredients at the farms, feed handling practices on the farm, and other issues, such as origin of the feed ingredients. Other actions would include  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 6 miles of the various farms, with most of the farms located 2 miles or less from the feed mill. 

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Q: What is the size and scope of the recall?

A: The recent Wright County Egg in Iowa and Hillandale Farms of Iowa, Inc. voluntary recalls of shell eggs are considered nationwide recalls. Shell eggs from Wright County Egg were sold to distributors and wholesalers in 22 states and Mexico, who then distributed the shell eggs further throughout the country. According to Wright County Egg of Iowa, 380 million of their shell eggs are being recalled under many different brand names.  According to Hillandale Farms of Iowa, Inc. additional shell eggs now under recall went to grocery stores, distributors, and wholesalers in 14 states; these entities then distributed the shell eggs further throughout the country. According to these two companies, more than 500 million eggs are now involved in the nationwide recall.

Q: Is this the largest Salmonella Enteritidis outbreak recorded?

A: According to The Centers for Disease Control and Prevention, this represents the largest Salmonella Enteritidis (SE) outbreak reported since the start of outbreak surveillance in the early 1970s. The largest previous outbreak was in 1994, due to contaminated commercial ice cream, with 743 reported cases.

Q: Does the FDA expect more companies to recall?

A: This is an ongoing investigation.  FDA is working with Wright County Egg and Hillandale Farms of Iowa, Inc. to identify their distributors and wholesalers who distributed the recalled shell eggs further through the country and Mexico. Because these eggs are sold by different companies under different brand names, we may see some smaller scale or “sub recalls.”

Consumers should go to to view the most recent list.

Should FDA uncover information that leads to more contaminated shell eggs, then the Agency will work with the necessary parties to facilitate voluntarily recalls of the products and take the necessary steps to protect the safety of the public’s health. That additional information will be posted on the web site as it is confirmed.

Q: What have FDA investigators been looking for on the farms?

A: FDA investigators have been performing environmental assessments of farm conditions and practices including pest and rodent controls, biosecurity plans and controls; environmental monitoring; sanitary controls; and feed and laying hen sources. The investigators are also looking at commonalities between Wright County Egg and Hillandale Farms of Iowa, Inc.

Q: How does FDA know that recalled product has been removed from the marketplace?

A: FDA and its state partners are conducting checks at retail stores, wholesalers and distributors to make sure they received notification about the recall and that they have taken appropriate action to notify their customers and to remove recalled shell eggs from the shelves.

Q: How are eggs regulated by the Federal Government?

A: FDA has jurisdiction over the safety of foods in general, including shell eggs, under the Federal Food, Drug, and Cosmetic Act. FDA also has authority to take actions to help prevent the spread of communicable diseases under the Public Health Service Act. This authority includes regulating foods when foods may act as a vector of communicable disease, as eggs may for SE.

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The USDA has responsibility for implementing the Egg Products Inspection Act (EPIA), which it carries out through programs administrated by the Food Safety and Inspection Service (FSIS) and the Agricultural Marketing Service (AMS). FSIS has primary responsibility for the inspection of processed egg products to prevent the distribution into commerce of adulterated or misbranded egg products, while AMS conducts a surveillance program to ensure proper disposition of restricted shell eggs. Additionally, AMS provides grading and certification services on a voluntary basis. All shell eggs are eligible for these services, which are provided by the AMS Poultry Programs. The shell egg grading and certification services ensure that requirements are met for quality, weight, condition, and/or other factors. Finally, the USDA’s Animal and Plant Health Inspection Service (APHIS) administers programs for animal health, including an SE control program for flocks that supply chicks to egg laying operations. FDA has primary responsibility for the parts of the continuum that involve the production and processing of shell eggs.

Q: Are both farms subject to the Egg Safety Rule?

A: Yes, Wright County Egg in Iowa and Hillandale Farms of Iowa, Inc. are considered large egg producers with 50,000 or more laying hens. Therefore, they are subject to the rule that came into effect on July 9, 2010. The Egg Safety Rule requires preventive measures during the production of eggs in poultry houses and requires subsequent refrigeration during storage and transportation.

Q: Are both farms in compliance with the Egg Safety Rule? 

A: As one part of the ongoing outbreak investigation, FDA investigators are on the farms examining their compliance with the Egg Safety Rule. Also, FDA is examining possible sources of the contamination in this outbreak. Our focus remains on the prevention of more illnesses due to the consumption of contaminated shell eggs. 

Q: Is this outbreak the first test of the Egg Safety Rule?

We believe the Egg Safety Rule, once it is fully implemented by all shell egg producers, will reduce these types of SE outbreaks and prevent thousands of illnesses. The Egg Safety Rule went into effect July 9, 2010 for large producers, those that have 50,000 or more laying hens, a few months after CDC began to see an increase in illnesses associated with SE. The Rule takes full effect in July 2012, when smaller producers, those with 3000 or more but less than 50,000 laying hens, must be in compliance. However, FDA strongly encourages all egg producers to employ the measures in the Egg Safety Rule as soon as possible. FDA will continue to work with the industry to implement the important standards and testing mechanisms within this Rule.

Q: Why didn’t FDA require a vaccine for hens in the Egg Rule?

A: There are several commercially available vaccines for SE infection in laying hens. These vaccines may help reduce the likelihood of SE infection, but do not eliminate it entirely. In the proposed egg rule issued in 2004, FDA considered the evidence on vaccination and determined that “vaccines show promise in reducing the prevalence” of SE in laying hens. However, FDA concluded that “more information on the effectiveness of vaccines needs to be generated before we would mandate vaccination as a (SE) prevention measure.” FDA cited the small number of flocks vaccinated in existing trials of the vaccine.

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FDA received public comments following publication of the proposed rule. A few commenters called for FDA to include vaccination as a required part of the rule; some of these recommended that producers using vaccination should be allowed to follow a reduced testing regimen. Others stated that vaccination should be included only as a recommendation in control programs. In the final rule, FDA stated, “While vaccines have shown some promise in the lab, there is insufficient evidence from field trials about their efficacy to estimate any benefit from their use” and “there is no vaccine that has been shown to be efficacious in the field.” As a result, FDA did not require vaccination. FDA did encourage the use of the vaccine as a prevention measure where individual producers have had success with vaccination.

FDA is now working with USDA to review all recent and relevant data on these vaccines and determine whether additional recommendations or requirements are appropriate.

Q: What is the FDA doing to help farms implement the Egg Safety Rule?

A: FDA is working with United Egg Producers and other organizations to educate producers and those who store and/or transport eggs about the new requirements. FDA will continue its outreach sessions with producers and others around the country this fall. In the meantime, the FDA continues to issue guidance to all shell egg producers on how to implement these regulations. Soon, the FDA will begin inspecting all large shell egg producers to make sure they are in compliance with the Egg Safety Rule.

Q: If a consumer has eggs in his or her refrigerator that are not in a package, how does he or she know if the eggs are safe?

A: If consumers are unsure about the source of their shell eggs, they are urged not to eat them and to throw them away immediately or return them to the store. They can check the site’s searchable database at for eggs that have been recalled and for safe handling practices. 

Q: Are the recalled eggs incorporated into any processed products that consumers should be aware of, such as cookie dough or something else that is uncooked?

A: Pasteurized egg products and pasteurized in-shell eggs are not affected by this recall and are safe to eat. Many manufacturers use pasteurized egg products in ready-to-cook foods, such as raw cookie dough. FDA continues the traceback efforts to see if any smaller food operations may be using fresh eggs in ready-to-cook products. If we do find any, we will advise the public as necessary. But the FDA would like to remind all consumers against eating any raw cookie dough or any raw food products that may contain shell eggs that are supposed to be cooked or baked before eating because they could make you sick.

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