Despite decades of food safety education, improved regulation, and technological advances, Salmonella continues to be one of the most common causes of foodborne illness worldwide. In the United States alone, the Centers for Disease Control and Prevention (CDC) estimates that Salmonella causes about 1.35 million infections, 26,500 hospitalizations, and 420 deaths each year. Its persistence in the food supply and its ability to evade detection make Salmonella a formidable and ongoing public health threat.
But why exactly is Salmonella so widespread, and why haven’t we been able to beat it?
What Is Salmonella?
Salmonella is a genus of bacteria that includes more than 2,500 serotypes, with Salmonella Enteritidis and Salmonella Typhimurium being the most common causes of human infection. Once ingested, these bacteria can cause salmonellosis, an illness marked by diarrhea, fever, stomach cramps, nausea, and sometimes vomiting.
While most healthy people recover without treatment in a few days, Salmonella can cause serious complications in young children, the elderly, pregnant individuals, and people with weakened immune systems. In severe cases, the bacteria can enter the bloodstream and spread to other parts of the body, requiring hospitalization and antibiotic treatment.
Where Is Salmonella Found?
One of the reasons Salmonella is so hard to control is its ability to thrive in a wide variety of foods and environments. Unlike some pathogens that are limited to certain food groups, Salmonella can be found in:
- Raw poultry and meat
- Eggs and egg products
- Dairy products
- Fresh produce, such as lettuce, tomatoes, melons, and sprouts
- Unpasteurized juices
- Dry goods, including peanut butter and spices
- Pet food and reptiles or backyard poultry, which can spread the bacteria to humans
The versatility of Salmonella means that even unexpected foods, like frozen pot pies, tahini, or raw flour, can be implicated in outbreaks.
Why Salmonella Is So Successful
Several biological and environmental factors contribute to Salmonella’s success as a leading foodborne pathogen:
1. Low Infectious Dose
It doesn’t take much. Ingesting as few as 10–100 bacterial cells can cause illness, depending on the strain and the person’s immune status.
2. Resilience
Salmonella can survive under challenging conditions, including:
- Low moisture environments (like dry cereals or spices)
- Freezing and refrigeration (though it doesn’t grow, it survives)
- Acidic conditions, allowing it to endure stomach acid and reach the intestines
3. Animal Reservoirs
Many farm animals, especially poultry and cattle, can carry Salmonella without showing symptoms. This makes it hard to identify contaminated animals before processing.
4. Asymptomatic Carriers
Humans can become carriers of Salmonella, shedding the bacteria in feces long after symptoms have passed, potentially spreading it to others or contaminating surfaces and foods.
Outbreaks, Recalls, and Economic Impact
Salmonella is one of the most frequently cited pathogens in food recalls. High-profile outbreaks have been linked to everything from eggs and chicken to cantaloupes and frozen foods. These events can lead to massive recalls, lawsuits, and public concern.
Beyond the human cost, salmonellosis results in billions of dollars in lost productivity, medical expenses, and regulatory enforcement each year. In agriculture, producers and processors suffer reputational damage and financial penalties when Salmonella is traced to their products.
Prevention: Where It Works and Where It Fails
Controlling Salmonella requires intervention at every step of the food chain, including:
- Farm level: Biosecurity, vaccination of poultry, sanitation
- Processing facilities: Pasteurization, cooking, and cleaning protocols
- Retail and food service: Safe storage, food handling, and cross-contamination prevention
- At home: Cooking meat thoroughly, avoiding raw eggs, washing produce, and hand hygiene
Yet, despite these efforts, gaps persist. Cross-contamination, inadequate cooking, and inconsistent food safety practices can all result in Salmonella slipping through the cracks.
Additionally, many people mistakenly assume that only raw meat poses a risk, overlooking fresh produce, ready-to-eat foods, and even petting zoos as potential sources.
Surveillance and Detection
Technological tools like whole genome sequencing (WGS) have significantly improved outbreak detection and response. Public health labs can now link human illness to contaminated food sources with unprecedented accuracy. While this has led to faster recalls and better traceability, it also reveals just how common Salmonella contamination still is.
Ongoing efforts from the CDC’s PulseNet, the FDA’s GenomeTrakr, and international monitoring networks are helping to identify outbreaks sooner and prevent further illness.
Final Note
Salmonella remains one of the leading causes of food poisoning not because of a single failure, but due to a complex web of biological, environmental, and human factors. Its ability to hide in a wide array of foods, survive harsh conditions, and infect with a small dose makes it particularly difficult to control.For consumers, the best defense is awareness and safe food practices. For regulators and producers, it’s a reminder that vigilance must be ongoing, not reactive. Salmonella may be ancient, but the tools to outsmart it are finally catching up. It’s up to us to use them.
