What Is the Number One Food That Causes Salmonella? Uncovering the Truth Behind the Leading Source

Understanding Salmonella: A Dangerous but Preventable Pathogen

Salmonella is one of the most common causes of foodborne illness worldwide, affecting millions of people every year. According to the Centers for Disease Control and Prevention (CDC), Salmonella is responsible for approximately 1.35 million infections, 26,500 hospitalizations, and 420 deaths annually in the United States alone. While many associate food poisoning with symptoms like nausea, vomiting, and diarrhea, Salmonella infections can be far more serious—particularly in young children, the elderly, and individuals with compromised immune systems.

The bacteria are naturally found in the intestines of animals and can be transmitted to humans through the consumption of contaminated food or water. While numerous food types can harbor Salmonella, one stands out as the primary culprit behind outbreaks and individual cases alike: raw or undercooked eggs.

Why Eggs Are the Leading Cause of Salmonella Infections

The Science Behind Salmonella in Eggs

Eggs are a leading cause of Salmonella transmission due to both external and internal contamination. Salmonella Enteritidis, the strain most commonly linked to eggs, can infect the ovaries of healthy-looking hens and contaminate the egg before the shell even forms. This means that even clean, uncracked eggs with no visible signs of dirt or damage can carry the bacteria inside.

External contamination occurs when eggs come into contact with fecal matter during laying or handling. Bacteria can penetrate the porous shell, especially if the eggs are washed improperly or stored in unsuitable temperatures. Once inside, Salmonella can multiply rapidly, particularly if eggs are stored at room temperature.

Where Does the Contamination Begin?

The journey from hen to table involves several potential contamination points:

Farm conditions: Overcrowding, poor sanitation, and lack of biosecurity in poultry farms can promote the spread of Salmonella among hens.
Egg collection and handling: If eggs are not collected promptly or are placed on dirty surfaces, bacteria can penetrate the shell.
Packaging and storage: Eggs stored above 40°F (4°C) allow Salmonella to multiply. Improper refrigeration during transport or at retail outlets exacerbates the risk.
Home preparation: Raw or undercooked eggs in dishes like homemade mayonnaise, Caesar salad dressing, or cookie dough increase exposure risk.

High-Risk Foods Containing Raw Eggs

It’s not just whole eggs that pose a threat. Many beloved recipes and commercial products contain raw or lightly cooked eggs, increasing the risk of Salmonella transmission. Some widespread examples include:

Homemade ice cream – Recipes that use raw eggs for custard bases can be hazardous if not fully cooked.
Raw cookie or cake batter – A common temptation, but one that carries real risks.
Mayonnaise and salad dressings – Commercial versions use pasteurized eggs, but homemade versions often do not.
Mousses and desserts – Dishes like tiramisu or lemon meringue pie that include raw or partially cooked eggs.
Soft-scrambled or poached eggs – Any egg dish not cooked to an internal temperature of 160°F (71°C) may harbor live bacteria.

Recent Outbreaks and Epidemiological Evidence

Data from government health agencies substantiates eggs as the number one food source for Salmonella. According to the CDC’s Foodborne Outbreak Online Database, between 2010 and 2020, over 20% of Salmonella outbreaks with a confirmed food source were linked to eggs. Notable examples include:

2022 Multi-State Egg Recall

In late 2022, a massive recall of nearly 200 million eggs was ordered after testing revealed Salmonella contamination at a major Midwestern egg production facility. Over 70 people across ten states reported illness, with hospitalizations confirmed in high-risk individuals.

2010 Egg Recall – One of the Largest in U.S. History

Wisconsin-based Wright County Egg and Hillandale Farms recalled more than 550 million eggs after their products were tied to a nationwide Salmonella outbreak. The CDC linked the outbreak to 1,953 confirmed cases, highlighting the massive scale of contamination possible through egg supply chains.

Global Perspective: Eggs and Salmonella Beyond the U.S.

The association between eggs and Salmonella isn’t limited to the United States. Countries across Europe, Asia, and South America have reported similar patterns. For example:

In the European Union, regulatory bodies like the European Food Safety Authority (EFSA) regularly issue warnings about Salmonella in eggs and implement vaccination programs for laying hens.
Japan has adopted strict egg-washing and refrigeration protocols after experiencing numerous Salmonella outbreaks in the 1990s. The country now uses widespread hen vaccination, significantly reducing infection rates.
In developing nations, where refrigeration and food safety infrastructure are less consistent, eggs are often consumed raw or partially cooked, increasing the risk of infection.

These global trends underscore that while the risk is universal, preventive measures can significantly reduce Salmonella transmission.

How Salmonella Affects the Body

After consuming contaminated food, symptoms of Salmonella infection typically appear within 6 to 72 hours. Common symptoms include:

Diarrhea – Often watery and sometimes bloody
Abdominal cramps – Can be severe and debilitating
Nausea and vomiting
Fever – Usually mild to moderate
Headache and muscle pain

Most healthy adults recover within 4 to 7 days without medical treatment. However, in vulnerable populations, the infection can lead to sepsis, reactive arthritis, or even death. Infants, pregnant women, older adults, and those with weakened immune systems are particularly at risk for severe complications.

In rare cases, Salmonella can cause typhoid fever, a serious and potentially life-threatening illness caused by a different strain, Salmonella Typhi, which is usually waterborne but can be food-related in areas with poor sanitation.

Symptoms Timeline: What to Expect After Exposure

Time After Exposure	Symptoms and Effects
6–72 hours	Onset of diarrhea, fever, abdominal cramps
Day 2–3	Peak symptoms; dehydration risk increases
Day 4–7	Symptoms begin to wane in healthy individuals
After 7 days	Potential complications in at-risk groups; prolonged illness possible

Why Eggs Are Riskier Than Other Contaminated Foods

There are several key reasons why eggs consistently rank as the number one food causing Salmonella:

Widespread Consumption

Eggs are a dietary staple in many cultures. They appear in breakfasts, baked goods, sauces, and even pet food. The sheer volume of consumption increases the likelihood of exposure.

Use in Raw or Lightly Cooked Forms

Unlike chicken, which is almost always cooked before eating, eggs are frequently consumed raw or undercooked—as runny yolks, in beverages, or in uncooked batters.

Internal Contamination

External contamination can be mitigated by washing, but internal contamination from the hen poses a unique challenge. No external cleaning method can remove bacteria inside the egg.

Limited Consumer Awareness

Many people don’t realize that store-bought eggs can contain Salmonella. There’s a widespread misconception that clean, store-bought eggs are safe to eat raw, especially in dishes like hollandaise or Caesar dressing.

How to Minimize the Risk of Salmonella from Eggs

Prevention is key. Fortunately, several evidence-based strategies can significantly reduce your risk of infection.

Choose Pasteurized Eggs When Possible

Pasteurized eggs are heated to a temperature sufficient to kill Salmonella without cooking the egg. They are clearly labeled and are ideal for recipes requiring raw eggs. Look for brands that are USDA-approved for pasteurization.

Cook Eggs Thoroughly

Hard-boil, scramble, or fry eggs until both the yolk and white are firm. Avoid recipes that rely on partially cooked eggs unless pasteurized eggs are used.

Refrigerate Promptly and Properly

Keep eggs refrigerated at 40°F (4°C) or below. Do not leave eggs at room temperature for more than two hours, or one hour if the ambient temperature is above 90°F (32°C). Refrigeration slows bacterial growth and extends shelf life.

Avoid Cross-Contamination

Use separate utensils and surfaces for raw eggs. Wash hands, counters, and equipment with hot, soapy water after handling raw eggs.

Check Expiration and Recall Notices

Always check the “sell-by” or “use-by” date on egg cartons. Subscribe to recall alerts from the Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA).

Industry and Government Efforts to Reduce Salmonella in Eggs

Recognizing the public health impact, regulatory agencies and the egg industry have taken significant steps to reduce contamination levels.

FDA Egg Safety Rule (2010)

This rule mandates that large egg producers implement safety measures including:

Regular testing for Salmonella in hen houses
Vaccination of laying hens
Rodent and pest control
Refrigeration during storage and transport

Voluntary Industry Practices

Many producers go beyond regulations by using on-farm biosecurity protocols, improved hen housing, and advanced sanitation techniques. Some have also adopted in-shell pasteurization technologies that treat eggs post-harvest.

Consumer Education Campaigns

The CDC, FDA, and nonprofit organizations like the Partnership for Food Safety Education run public awareness programs such as “Fight BAC!®” to educate consumers about safe egg handling and cooking practices.

Myths About Eggs and Salmonella: What’s True and What’s Not?

Myth: Organic or Free-Range Eggs Are Safer

False. While production practices may differ, organic or free-range eggs are not inherently free of Salmonella. In fact, some studies suggest that free-range hens may have higher exposure to contaminated environments due to outdoor access.

Myth: Washing Eggs at Home Makes Them Safer

False and Potentially Dangerous. Commercial eggs in the U.S. are washed before packaging, but washing at home can damage the egg’s natural protective cuticle and increase the risk of bacteria entering through the shell pores.

Myth: You Can Tell If an Egg Is Contaminated by Its Appearance

False. Salmonella-contaminated eggs look, smell, and taste normal. There is no visible sign of bacterial presence.

Myth: Cooking Eggs Slightly—Like a Runny Yolk—Is Safe

Unreliable. While heat kills Salmonella, the internal temperature must reach at least 160°F (71°C). Runny yolks may not achieve this, especially in sous-vide or low-temperature cooking.

The Bottom Line: What You Need to Know

Based on epidemiological data, outbreak reports, and food safety research, raw or undercooked eggs are the number one food responsible for Salmonella infections. Their widespread use in both commercial and home-cooked foods, combined with the risk of internal contamination, makes them a persistent hazard.

While the risk cannot be eliminated entirely, it can be dramatically reduced through smart consumer choices—like opting for pasteurized eggs, cooking them thoroughly, and storing them properly. Public health efforts in regulation, vaccination, and education continue to improve egg safety, but individual vigilance remains crucial.

The next time you crack an egg for a sunny-side-up breakfast or lick the spoon after mixing cookie dough, remember: every egg carries a small but real risk. By following safe food handling practices, you can enjoy this nutritious and versatile food without compromising your health.

Final Tips for Safer Egg Consumption

Always buy eggs from refrigerated cases.
Use pasteurized eggs for any recipe with raw or lightly cooked eggs.
Cook eggs until both yolk and white are firm.
Refrigerate eggs promptly and don’t leave them out for extended periods.
Wash hands and surfaces after handling raw eggs.

What is the number one food that causes salmonella?

The number one food responsible for the majority of salmonella outbreaks is chicken. Raw or undercooked poultry products, particularly chicken, are frequently contaminated with Salmonella bacteria during the slaughtering and processing stages. Even a small amount of undercooked chicken or cross-contamination in the kitchen can introduce the bacteria into the human body, leading to infection. According to data from the Centers for Disease Control and Prevention (CDC), chicken is consistently implicated in more cases of salmonella than any other food source in the United States.

Salmonella naturally resides in the intestines of poultry, and despite modern food safety practices, contamination remains a persistent challenge. Improper handling, such as using the same cutting board for raw chicken and vegetables without cleaning it, increases the risk of foodborne illness. Public health campaigns continue to emphasize safe food preparation, including thorough cooking to an internal temperature of 165°F (74°C), proper refrigeration, and avoiding cross-contamination in the kitchen.

How does salmonella get into chicken?

Salmonella enters the chicken food supply primarily through the birds’ own digestive systems. The bacteria are naturally present in the intestines of chickens and can contaminate meat during slaughter when intestinal contents come into contact with the carcass. Even chickens raised in clean environments can carry Salmonella without showing signs of illness, making detection difficult before processing. Environmental factors such as contaminated feed, water, or contact with infected birds further contribute to bacterial spread within flocks.

Processing plants use various interventions like antimicrobial rinses and strict sanitation protocols to reduce contamination, but they cannot eliminate Salmonella entirely. Additionally, improper hygiene during farm-to-table handling increases the likelihood of bacterial transmission. While regulatory agencies monitor and enforce safety standards, some level of contamination risk remains inherent in poultry production. This underscores the importance of proper cooking and food safety practices at home.

Are eggs a major source of salmonella too?

Yes, eggs are another significant source of salmonella, particularly strains like Salmonella Enteritidis. This type of bacteria can infect the ovaries of healthy-looking hens and contaminate the eggs before the shells are even formed. Unlike external contamination, which can be reduced by washing, internal contamination means that even clean, uncracked eggs can carry the bacteria. As a result, consuming raw or undercooked eggs—such as in homemade mayonnaise, cookie dough, or soft-scrambled eggs—puts individuals at risk.

The risk of salmonella from eggs has decreased over time due to improved hen vaccination programs and stricter on-farm regulations. However, outbreaks still occur, and not all egg producers follow the same safety measures. It is recommended to purchase pasteurized eggs or egg products when consuming them raw and to cook eggs until both the yolk and white are firm. Refrigerating eggs promptly also helps inhibit bacterial growth and reduces the chance of illness.

Can vegetables cause salmonella poisoning?

Yes, vegetables can and have caused significant salmonella outbreaks, even though they are not the primary source. Contamination occurs when raw produce comes into contact with Salmonella-contaminated water, animal manure used as fertilizer, or contact with infected animals or humans during handling. Leafy greens, tomatoes, sprouts, and melons have been linked to multiple outbreaks due to their exposure to environmental hazards and frequent consumption raw.

Because vegetables are not typically cooked before eating, any surface contamination remains a risk. Rinsing produce under running water can help reduce—but not eliminate—bacteria. Outbreaks tied to produce often trace back to irrigation water polluted by nearby livestock operations. As the popularity of fresh and organic produce increases, so does the importance of stringent agricultural safety practices and consumer diligence in washing fruits and vegetables thoroughly before consumption.

What are the symptoms of a salmonella infection?

Salmonella infection, also known as salmonellosis, typically causes symptoms within six hours to six days after consuming contaminated food. Common signs include diarrhea, abdominal cramps, fever, nausea, vomiting, and headache. Most people experience mild to moderate symptoms that resolve on their own within four to seven days, though the illness can be more severe in infants, older adults, and individuals with weakened immune systems.

In serious cases, the infection can spread beyond the intestines, leading to life-threatening complications such as bacteremia or reactive arthritis. Dehydration is a common concern due to fluid loss from diarrhea and vomiting. Individuals with prolonged or severe symptoms should seek medical attention. While most recover without antibiotics, severe infections may require hospitalization and targeted treatment, especially when the bacteria invade the bloodstream.

How can I prevent salmonella when cooking chicken?

To prevent salmonella when cooking chicken, always ensure it reaches an internal temperature of at least 165°F (74°C), measured with a food thermometer in the thickest part of the meat. Visual cues like clear juices or lack of pinkness are not reliable indicators, so using a thermometer is critical. Additionally, avoid washing raw chicken before cooking, as this can spread bacteria through water splashes onto countertops, utensils, and other foods.

Use separate cutting boards, plates, and utensils for raw chicken and ready-to-eat foods to avoid cross-contamination. Wash hands thoroughly with soap and water after handling raw poultry, and clean all surfaces and tools with hot, soapy water. Refrigerate leftovers within two hours of cooking—or one hour if the ambient temperature is above 90°F—and never thaw chicken at room temperature. These practices significantly reduce the risk of salmonella transmission.

Is organic or free-range chicken safer from salmonella?

There is no conclusive evidence that organic or free-range chicken is inherently safer than conventionally raised chicken when it comes to salmonella risk. While these chickens may be raised in different environments with access to the outdoors and fed organic diets, they can still be exposed to Salmonella through contaminated soil, water, wild birds, or insects. In fact, some studies suggest that outdoor access may increase exposure to environmental pathogens.

The key factors influencing salmonella levels are hygiene practices at the farm, processing controls, and handling during storage and preparation. Organic and free-range labels refer more to animal welfare and farming practices than to food safety outcomes. Regardless of labeling, all raw chicken—whether from conventional, organic, or free-range sources—should be treated as potentially contaminated and handled with the same food safety precautions to minimize illness risk.