Reviewed by: Darwin Benedict,BSc Biochem, MPH, Co-Editor. January 23, 2026

A Comprehensive Guide to One of the World’s Most Common Foodborne Illnesses

Foodborne diseases are a major public health challenge globally, especially in low- and middle-income countries. Among them, salmonellosis stands out as a leading cause of acute gastrointestinal illness and food poisoning. This disease not only affects millions of people every year but also places a heavy burden on health systems and economies. Understanding salmonellosis—its causes, common sources of infection, signs and symptoms, and how to prevent it—is essential for consumers, food handlers, and public health professionals alike.

What Is Salmonellosis?

Salmonellosis is an infection caused by bacteria of the genus Salmonella. These bacteria are among the most common causes of foodborne illness worldwide and are a significant contributor to diarrhoeal diseases. Salmonella bacteria are widely distributed in the intestines of humans, animals (especially poultry, cattle, and pigs), and in contaminated environments.

There are more than 2,500 known serotypes (types) of Salmonella, but only a subset causes most human infections. In general, salmonellosis refers to what is often called non-typhoidal Salmonella infection, which primarily results in gastroenteritis.

While most cases are mild and self-limiting, complications can occur—especially in vulnerable individuals such as young children, the elderly, and people with weakened immune systems.

Causative Agent

The bacteria that cause salmonellosis belong to the genus:

Salmonella species

• Salmonella enterica — the species most commonly responsible for human infections.
• Numerous subtypes and serotypes exist, with S. enterica serovar Enteritidis and S. enterica serovar Typhimurium among the most frequent in human disease.

These bacteria are adapted to survive in the intestinal tracts of animals and humans and can be shed in feces. When contaminated food or water is consumed, the bacteria invade the gut lining and trigger inflammation, leading to illness.

How Salmonellosis Is Transmitted

Salmonella transmission is primarily fecal–oral, meaning the bacteria exit the body in feces and enter another person’s mouth through contaminated food, water, hands, or surfaces.

Common transmission pathways include:

• Contaminated food and water: Raw or undercooked meat, poultry, eggs, and unpasteurized milk are classic sources; produce can also become contaminated through irrigation with unsafe water.
• Cross-contamination: Juices from raw meat or poultry can contaminate other foods or kitchen tools.
• Poor hygiene and sanitation: Food handlers with contaminated hands can spread bacteria directly to foods.
• Contact with animals: Pets, livestock, or reptiles carrying Salmonella can shed bacteria in their feces.

Because Salmonella bacteria can exist in foods that look, smell, and taste normal, infection is not always predictable based on food appearance alone.

Common Sources of Contamination

1. Animal-Derived Foods

• Poultry and poultry products: Chicken and turkey are leading sources of Salmonella contamination.
• Eggs: Salmonella can be present on the shell surface or inside eggs.
• Meat and pork: Contamination can occur during slaughter and processing.
• Unpasteurized dairy products: Raw milk and products made from it can carry the bacteria.

2. Produce and Fresh Foods

• Fruits and vegetables can become contaminated if irrigated or washed with contaminated water or if they come into contact with raw meat juices.

3. Water

• Drinking or using unsafe water for preparing food can introduce bacteria.

4. Cross-Contamination in Kitchens

• Cutting boards, utensils, or surfaces contaminated by raw foods can spread bacteria to ready-to-eat foods.

Signs and Symptoms of Salmonellosis

Symptoms generally appear 6 to 72 hours after exposure, but typically within 12–36 hours.

Common Symptoms

Salmonellosis often presents as acute gastroenteritis with:

• Diarrhea (sometimes bloody)
• Abdominal cramps
• Fever
• Nausea and vomiting
• Headache
• Muscle pains or chills

These symptoms usually last 4–7 days, and most healthy individuals recover without medical treatment. However, diarrhea can lead to dehydration, especially in young children, older adults, and those with compromised immunity.

Severe or Complicated Illness

In some cases, infection can spread beyond the gut, leading to bacteremia (bacteria in the blood) and serious complications such as:

• Meningitis
• Osteomyelitis (bone infection)
• Septic arthritis
• Reactive arthritis (a post-infection inflammatory condition)
  These complications are more likely in vulnerable groups.

When to Seek Medical Help

Most salmonellosis cases resolve without clinical intervention, but medical help is essential if any of the following occur:

❗ Severe or Prolonged Symptoms

• Persistent diarrhea lasting more than 3 days.
• High fever (e.g., above 102°F / 39°C).
• Bloody stools or severe abdominal pain.

❗ Signs of Dehydration

Dehydration due to diarrhea and vomiting requires immediate care, particularly in:

• Infants and young children
• Older adults
• People with chronic illness

Signs of dehydration include:

• Little or no urine output
• Dry mouth and throat
• Dizziness or light-headedness
• Dark-colored urine

❗ High-Risk Populations

Seek medical advice promptly if the sick person is:

• A baby or infant
• Pregnant woman
• Older adult (65+)
• Immunocompromised individuals (e.g., HIV/AIDS, cancer treatment)

Treatment Basics

🩺 Supportive Care

For most people, treatment involves:

• Staying well-hydrated with fluids and electrolytes
• Eating easily digestible foods as tolerated

Antibiotics are not routinely recommended for mild cases, as they do not shorten illness duration and may promote antibiotic resistance.

🩹 Severe Cases

In serious infections (e.g., bloodstream involvement, high-risk patients), antibiotics may be prescribed under medical supervision.

Preventive Measures

Reducing the risk of salmonellosis depends on safe food handling and good hygiene practices at every step, from farm to fork:

1. Clean Hands and Surfaces

• Wash hands with soap and clean water before handling food, after using the toilet, and after touching animals.
• Clean kitchen surfaces and utensils frequently.

2. Separate Raw and Cooked Foods

Avoid cross-contamination by using separate cutting boards and plates for raw meats and ready-to-eat foods.

3. Cook Thoroughly

Cooking food to safe internal temperatures destroys Salmonella:

• Poultry → 165°F (74°C)
• Ground meats → 160°F (71°C)
• Eggs → until yolk and white are firm

4. Chill and Store Safely

Refrigerate perishable foods promptly (below 5°C / 41°F) and avoid leaving foods in the “danger zone” for extended periods.

5. Use Safe Water and Pasteurization

Drink safe water and consume pasteurized dairy products.

6. Be Cautious with Pets and Animals

Wash hands after handling pets or farm animals.

7. Travel Safely

In areas with poor sanitation, boil or treat water and avoid street foods if hygiene is uncertain.

Global Impact and Burden

Foodborne diseases—including salmonellosis—are a major cause of illness worldwide. The World Health Organization (WHO) estimates that unsafe food leads to hundreds of millions of illnesses annually, disproportionately affecting children under 5 in low- and middle-income countries.

Salmonella remains one of the most common bacterial causes of diarrhoeal disease globally, with many cases unreported due to limited access to diagnostics.

Conclusion

Salmonellosis is a widespread and potentially serious foodborne disease caused by Salmonella bacteria. While most cases are mild, the risk of complications and dehydration—especially among vulnerable populations—makes awareness, early recognition, and prevention critical.

Effective prevention relies on clean hands, safe food handling, proper cooking, and good hygiene practices from the kitchen to the community. By understanding the risk factors and preventive measures, individuals, families, and food handlers can play a crucial role in reducing the burden of this preventable illness.

References

• WHO – Salmonella (non-typhoidal)
https://www.who.int/foodsafety/areas_work/foodborne-diseases/salmonella/en/

• CDC – Preventing Salmonella Infection
https://www.cdc.gov/salmonella/prevention/index.html

• CDC – Clinical Overview of Salmonellosis
https://www.cdc.gov/salmonella/hcp/clinical-overview/index.html

• FDA – Salmonella (Salmonellosis)
https://www.fda.gov/food/foodborne-pathogens/salmonella-salmonellosis