Eggs are a staple in kitchens around the world – scrambled, poached, boiled, baked into cakes, or served sunny-side up. Despite their versatility and nutritional value, eggs come with a hidden risk: Salmonella, one of the leading causes of foodborne illness globally. For decades, public health officials have worked to reduce Salmonella contamination in eggs, yet outbreaks and recalls still occur. Understanding the connection between eggs and Salmonella is key to keeping our food safe.
What Is Salmonella?
Salmonella is a genus of bacteria that causes salmonellosis, a foodborne illness characterized by diarrhea, stomach cramps, fever, and sometimes vomiting. Most people recover without medical treatment in 4 to 7 days, but vulnerable populations, such as infants, older adults, pregnant individuals, and people with weakened immune systems, may experience severe illness or require hospitalization.
There are over 2,500 types of Salmonella, but Salmonella Enteritidis is the serotype most commonly associated with eggs.
How Do Eggs Become Contaminated?
There are two primary ways eggs can become contaminated with Salmonella:
1. Contamination from the Outside (Shell Contamination)
Eggs can pick up Salmonella from contaminated surfaces during laying or processing. If a hen lays an egg in unsanitary conditions, such as on dirty litter or feces, the bacteria can attach to the eggshell. If not washed or handled properly, these bacteria may survive and be transferred during handling or cracking.
2. Contamination from the Inside (Internal Contamination)
More concerning is the possibility of internal contamination. Salmonella Enteritidis can infect a hen’s ovaries, meaning the bacteria can be present inside the egg before the shell is even formed. This makes external sanitization ineffective in preventing illness from raw or undercooked eggs.
Why Eggs Are a Common Vehicle for Salmonella
Eggs are particularly risky because they are often:
- Eaten raw or lightly cooked (e.g., in homemade mayonnaise, hollandaise sauce, eggnog, or soft-boiled dishes)
- Stored improperly, allowing bacteria to multiply
- Used in high volume in commercial kitchens and food service settings, increasing the risk of contamination if even one egg is tainted
The high protein and moisture content of eggs also make them a perfect breeding ground for bacteria if they are left at room temperature too long.
A History of Outbreaks
In the 1980s and 1990s, Salmonella Enteritidis emerged as a significant public health threat in the U.S., linked to a sharp rise in egg-related illnesses. At its peak, this strain caused tens of thousands of illnesses annually.
One of the largest modern outbreaks occurred in 2010, when more than 500 million eggs were recalled due to Salmonella Enteritidis contamination, resulting in thousands of reported illnesses. More recently, in 2025, August Egg Company recalled brown cage-free and organic eggs after a multistate outbreak that sickened 134 people, hospitalized 38, and resulted in one death.
Prevention at the Farm Level
In response to repeated outbreaks, significant regulatory changes have been implemented. In 2010, the FDA introduced the Egg Safety Rule, which requires:
- Refrigeration of eggs during storage and transport
- Salmonella testing for laying hens
- Strict biosecurity measures to reduce contamination in henhouses
- Cleaning and disinfection of poultry environments
Some egg producers also vaccinate their hens against Salmonella, a practice shown to significantly reduce bacterial presence in flocks.
Safe Handling Tips for Consumers
Despite industry controls, Salmonella can still make it into grocery stores and home kitchens. The CDC and FDA recommend the following precautions:
- Cook eggs until both the yolk and white are firm.
- Use pasteurized eggs for recipes that call for raw or lightly cooked eggs (e.g., Caesar dressing, tiramisu, raw cookie dough).
- Refrigerate eggs at or below 40°F (4°C) from purchase to use.
- Don’t use cracked or dirty eggs, which are more likely to harbor bacteria.
- Wash hands, utensils, and surfaces thoroughly after handling raw eggs.
- Consume cooked egg dishes promptly or refrigerate leftovers within two hours.
Why the Risk Persists
Although cases of egg-related Salmonella infections have declined in recent decades due to improved regulation and industry practices, outbreaks still occur. Factors that contribute to ongoing risk include:
- Inconsistent safety practices across farms and egg producers
- Consumer misunderstanding of labeling like “organic” or “cage-free,” which does not guarantee the absence of pathogens
- Global supply chains that can complicate traceability and response in the event of contamination
Final Note
Eggs are nutritious, affordable, and widely loved, but they must be handled with care. The connection between Salmonella and eggs is well established, but with smart practices at the farm, in the kitchen, and everywhere in between, the risk can be minimized.
Consumers shouldn’t fear eggs, but they should respect the potential for contamination, especially when preparing food for children, older adults, or anyone with a compromised immune system. Cracking eggs safely means more than avoiding shell fragments. It means understanding the hidden risks and acting accordingly.
