Salmonella Bacteria: Causes of Salmonellosis and Ways to Prevent It

Salmonella is a bacteria that can cause extreme diarrhea. Salmonella can be acquired from many places, including contaminated food and water. At times, Salmonella can be the cause of outbreaks of diarrhea and vomiting, including in the United States. When you know what Salmonella is and where it can be acquired, you can work to prevent it. Read on to learn more.

Key takeaways:

What is Salmonella?


Salmonella is a common cause of diarrhea. It affects the intestinal tract and causes a disease called salmonellosis. Salmonella is the most commonly reported cause of diagnosed diarrhea in the United States. The Salmonella bacteria typically live in animal and human gastrointestinal tracts. However, you can't see, smell, or taste Salmonella, making it challenging to identify until someone becomes ill. The fact that Salmonella cannot be easily identified with human senses makes it an ideal pathogen for foodborne disease outbreaks, especially if the food handler is unknowingly sick. Patients who have salmonellosis often mistakenly think that they have the “stomach flu.”

Types of Salmonella

Salmonella is a group of two species, six subspecies, and over 2,600 serotypes. Serotypes refer to variants of the bacteria that make it slightly different from other serotypes genetically. Nearly all Salmonella serotypes cause an illness known as salmonellosis. Salmonellosis is primarily characterized by diarrhea and cramping, along with some other mild symptoms.

Two serotypes of Salmonella cause very serious illnesses. Salmonella typhi and Salmonella paratyphi cause illnesses known as typhoid fever and paratyphoid fever. These infections are different from salmonellosis, and patients often get very ill when infected. Most typhoid fever and paratyphoid infections in the United States are acquired internationally while traveling.

Symptoms of salmonellosis

Some patients who are infected with Salmonella do not have any symptoms. Most patients begin to experience symptoms 8–72 hours after exposure to the bacteria.

Common symptoms of salmonella infection include:

  • Diarrhea
  • Stomach cramping
  • Vomiting
  • Nausea
  • Fever
  • Chills
  • Headache
  • Blood in stool (rare)

Signs to watch for with salmonellosis

If you have been diagnosed with or suspect you might have salmonellosis, be cautious of severe illness and seek medical attention if required. If you are dehydrated, sick for more than seven days, experiencing symptoms in other body systems (e.g., urinary tract infections), or in extreme pain, you may be experiencing complications of salmonella infection that require additional medical intervention.

What causes Salmonella to spread?

The most common way to become infected with Salmonella is consuming contaminated food and water.

While contaminated food and water are the most common sources of infection, they are not the only places to come in contact with the bacteria. Places that you might come in contact with the Salmonella bacteria include:

  • Contaminated cooked foods
  • Raw meat
  • Unpasteurized dairy
  • Unwashed fruits and vegetables
  • Contaminated or untreated water
  • Pets

Risk of Salmonella in the United States

In the United States, Salmonella can be acquired in a number of places, typically causing mild illness and resolving within a few days. When practicing good food hygiene, like thoroughly cooking food and washing hands, the day-to-day risk of salmonella infection is relatively low.

The Centers for Disease Control and Prevention estimate there are approximately 1.35 million cases of salmonellosis in America every year. These numbers are estimated, as many gastrointestinal infections go undiagnosed, as patients often do not seek testing and treatment because the infection typically resolves quickly.

Detection and treatment of Salmonella infection


Salmonella bacteria are identified via laboratory testing of stool samples. Samples can also be detected in bodily tissues or fluids, but stool samples are the most common test.

When Salmonella infection is diagnosed, treatment can take a few key forms. Some treatment plans include only maintaining fluids to avoid dehydration and waiting to see if the infection resolves on its own. In more serious infections or among patients who are expected to get more seriously ill, antibiotics are recommended. Patients who are likely to receive antibiotics include the elderly, individuals who are immune compromised, and infants.

Prevention of Salmonella infection

With so many sources of Salmonella and the potential to come in contact with the bacteria in many places, simple prevention strategies that can be applied broadly are helpful. Specifically, prevention tips for Salmonella include:

  • Maintain good hand hygiene. Wash hands regularly and with soap and water. Wash hands before preparing food, after handling pets, after using the bathroom, and more.
  • Use food safety tips. Cook all meat, poultry, seafood, and eggs according to public health guidelines, including reaching safe internal temperatures. Use a food thermometer if you are unsure if food is cooked.
  • Practice safe travel. When traveling internationally, be especially careful to maintain clean hands, eat foods that are fully cooked, and drink water that you trust to be safe for consumption, such as bottled water.

Salmonella is relatively common and easily acquired in the United States. Make safe food and water decisions, keep hands clean, and do not serve food to others if you are experiencing diarrhea.

If you are sick with diarrhea and think you may have salmonellosis, consider seeking laboratory testing to confirm the infection. If you are severely ill, experiencing extreme pain, dehydrated, or experiencing diarrhea for more than seven days, seek medical attention.


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