Overview of Salmonella

Salmonella is a genus of rod-shaped, gram-negative bacteria known to cause an infection called salmonellosis. It is one of the most common causes of foodborne illness globally, affecting millions each year. In the United States alone, Salmonella causes over 1.3 million infections, approximately 26,000 hospitalizations, and about 420 deaths annually.

The bacteria spread primarily through contaminated food and water, and sometimes from person to person or from animals to humans. Though most people recover without treatment within a week, severe cases can lead to life-threatening complications such as dehydration, sepsis, and typhoid fever.

Types of Salmonella

There are more than 2,500 known strains of Salmonella, but they are primarily classified into two species:

  • Salmonella enterica: The species responsible for the vast majority of human infections

  • Salmonella bongori: Less commonly involved in human disease

Among these, S. enterica serotypes Enteritidis and Typhimurium are most commonly associated with foodborne illness. Some strains are specific to certain animals:

  • S. Dublin: Common in cattle

  • S. Choleraesuis: Common in pigs

How Salmonella Is Transmitted

Salmonella is mainly transmitted through the ingestion of contaminated food or water. Sources include:

  • Raw or undercooked poultry, eggs, and meat

  • Unpasteurized milk or dairy products

  • Fresh produce like fruits and vegetables

  • Processed foods (e.g., peanut butter, frozen pot pies, and salami)

  • Cross-contaminated surfaces in kitchens

  • Contact with reptiles, amphibians, or pets

The risk of infection increases in the summer when warmer temperatures promote bacterial growth in food left unrefrigerated.

Symptoms of Salmonella Infection

Symptoms usually appear within 6 to 72 hours after exposure and may range from mild to severe. Common symptoms include:

  • Diarrhea (sometimes bloody)

  • Abdominal cramps

  • Fever (often above 100.4°F or 38°C)

Less frequent symptoms:

  • Nausea or vomiting

  • Headache

  • Muscle or body aches

  • Chills

  • Loss of appetite

  • Dizziness

Symptoms typically last 4 to 7 days. In some cases, the infection can spread to the bloodstream or other body parts, resulting in more serious conditions.

High-Risk Groups

While healthy adults may recover without complications, the following groups are at higher risk of severe illness:

  • Infants and children under 5 years old

  • Adults over 65

  • Immunocompromised individuals (e.g., those with HIV/AIDS, cancer, or organ transplants)

  • People with chronic conditions such as diabetes or inflammatory bowel disease (IBD)

  • Those taking medications that reduce stomach acid

Diagnosing Salmonella

Diagnosis involves identifying the bacteria through lab testing, typically using a stool sample. In severe or invasive infections, additional tests may include:

  • Blood culture

  • Urine culture

  • Bile sample

  • Cerebrospinal fluid (CSF) analysis

  • Bone marrow culture (rarely)

Prompt diagnosis is crucial for individuals with severe symptoms or weakened immune systems.

Treatment Options

Most cases of salmonellosis resolve on their own with supportive care. However, medical treatment may be necessary for severe or prolonged cases.

Supportive care includes:

  • Oral or intravenous fluids to prevent dehydration

  • Rest and a bland diet

  • Over-the-counter pain and fever relievers (e.g., acetaminophen or NSAIDs)

Antibiotics may be prescribed in high-risk or complicated cases. Common antibiotics include:

  • Ceftriaxone (Rocephin)

  • Azithromycin (Zithromax)

  • Ciprofloxacin (Cipro)

Avoid using antidiarrheal drugs without consulting a doctor, as they may prolong symptoms in bacterial infections.

Complications from Salmonella

Though most infections are mild, complications can arise, particularly in vulnerable populations. Major complications include:

  • Dehydration: Caused by excessive diarrhea and vomiting

  • Bacteremia: Bacteria entering the bloodstream, leading to sepsis

  • Typhoid fever: A severe illness caused by S. Typhi, resulting in prolonged high fever, intestinal pain, and possible perforation

  • Reactive arthritis: Joint inflammation following infection

Preventive Measures

Prevention largely depends on proper food safety practices and hygiene. Tips to avoid Salmonella infection include:

  • Wash hands before and after handling food

  • Cook meat and poultry thoroughly to safe temperatures

  • Avoid consuming raw eggs or unpasteurized milk

  • Wash fruits and vegetables before eating

  • Clean cutting boards and kitchen surfaces regularly

  • Store perishables in the refrigerator below 40°F (4°C)

  • Avoid cross-contamination by using separate utensils for raw and cooked food

  • Avoid food preparation if you have diarrhea

  • Practice good hygiene when handling animals, especially reptiles and birds

Salmonella and Pets

Pets, especially reptiles (like turtles and lizards), amphibians, and birds, can carry Salmonella bacteria. Pet owners should:

  • Wash hands after touching animals or cleaning their habitats

  • Avoid letting pets roam in food preparation areas

  • Clean pet dishes and cages frequently

Travel Precautions

When traveling to areas with poor sanitation, additional precautions should be taken:

  • Drink bottled or boiled water

  • Avoid raw foods (especially street food)

  • Eat only fruits you can peel yourself

  • Use hand sanitizers when soap and water are not available

When To See a Doctor

Seek immediate medical attention if you experience:

  • Diarrhea lasting more than 3 days

  • High fever

  • Blood in stool

  • Signs of dehydration (e.g., dry mouth, low urine output, dizziness)

  • Symptoms worsening or not improving

Living With Salmonella

Recovery from Salmonella infection may require a few days to a week. During recovery:

  • Stay hydrated

  • Follow a gentle diet (e.g., rice, toast, bananas, applesauce)

  • Get enough rest

  • Avoid contact with high-risk individuals until fully recovered

Recurrent infections are uncommon but may occur if proper hygiene and food safety are not maintained.