1. Salmonella Outbreak Pictures Slideshow
2. Summer Food Safety Quiz: Test Your Food Safety IQ
3. Food Poisoning Slideshow Pictures

Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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In this Article

• Salmonella poisoning facts
• What is Salmonella?
• What are Salmonella poisoning symptoms?
• How is Salmonella transmitted to humans?
• What are the risk factors for Salmonella infections?
• What are the unique situations that allow Salmonella to contaminate eggs?
• How do Salmonella spp. cause disease in people?
• How are Salmonella infections diagnosed?
• What is the treatment for Salmonella poisoning?
• What are the prognosis (outcome) and complications for Salmonella infections?
• How can Salmonella infection be prevented?
• Where can I find more information about Salmonella?
• Salmonella Outbreak - Slideshow
• Take the Quiz: Summer Food Safety
• Pictures of Food Poisoning - Slideshow
• Summer Food Safety FAQs
• Patient Comments: Salmonella - Treatments
• Patient Comments: Salmonella - Symptoms
• Salmonella Index

Although eggs have been known to occasionally transmit Salmonella bacteria to humans, there have been outbreaks in the last few years involving egg production plants. In the summer of 2010, an extremely large egg recall due to mainly Salmonella enteritidis contamination caused about 1,500 people to become ill. As a result, the FDA recalled over 500 million eggs.

What is unique about the 2010 Salmonella disease outbreak is that it is related to the "modern egg farming" situation found in many industrialized countries and how Salmonella is transmitted in domestic hens to their eggs.

Salmonella is reportedly transmitted in hens in at least three ways:

1. Direct surface contamination of eggs by contact with Salmonella-contaminated feed, feces, and cage material
2. Salmonella organisms transferred from hen ovaries to the yolk before the shell is formed in the hen's body
3. After the egg is laid and its surface contaminated with Salmonella, some of the bacteria reportedly can penetrate the shell and migrate to the yolk.

Unfortunately, "modern egg farming" techniques that are practiced by some producers augment Salmonella transfer to eggs by practicing techniques that result in massive egg production in extremely poor sanitary conditions for the hens. Once a "farm factory" gets Salmonella contamination, most of the hens and many of their eggs become contaminated. This cross-contamination in egg-producing facilities is usually due to lack of sanitary facilities and poor housing conditions for the hens. Many times, egg-producing hens are contaminated from outside sources, such as cattle feces and rodent feces due to poor quality control in feed and hen cage conditions. Currently, the FDA (and even the FBI) have looked into this egg recall to help determine if some producers have been negligent, especially in the housing methods used for poultry.

The two main producers under investigation are Hillandale Farms and Wright County Farms. However, eggs from these farms have been sold to at least 16 different suppliers. In industrialized countries, mass production techniques that make food readily available can also spread disease rapidly to many people. Vigilance by quality-control agencies and people who purchase foods (in this case, eggs) from bulk suppliers needs to be constant. The FDA suggests that if people are not sure if they have contaminated eggs, they should simply dispose of the eggs. Even in times when there are no recalls, people are advised to thoroughly cook items such as eggs and meat (especially hamburger meat) and drink from treated water sources. Other fluids need to be adequately pasteurized (heat-treated to reduce or eliminate pathogens) or sterilized. The FDA publishes its list of product recalls on the Internet and the site is frequently updated; the following web site, http://www.fda.gov/Safety/Recalls/default.htm will allow individuals to check on specific products and how to identify them.