What are the 6 foodborne pathogens?

December 25, 2025 •

3 min read

According to the World Health Organization, an estimated 600 million people—almost 1 in 10 globally—fall ill each year from eating contaminated food. To address this pervasive public health threat, authorities have focused on a core group of highly infectious microbes known as the "Big 6" foodborne pathogens.

Quick Summary

An overview of the six most infectious foodborne pathogens, including Norovirus, Salmonella, Shiga toxin-producing E. coli (STEC), Hepatitis A, Shigella, and nontyphoidal Salmonella. Key symptoms, transmission routes, and preventative measures are summarized.

Key Points

Know the Big 6: The most common and infectious foodborne pathogens include Norovirus, Nontyphoidal Salmonella, STEC (E. coli), Hepatitis A, Shigella spp., and Campylobacter spp..
Practice Proper Hygiene: Thorough handwashing for at least 20 seconds is crucial, especially for food handlers, to prevent the spread of pathogens like Norovirus and Shigella.
Prevent Cross-Contamination: Keep raw meats, poultry, and seafood separate from ready-to-eat foods to prevent the transfer of bacteria like Salmonella and Campylobacter.
Cook to Safe Temperatures: Use a food thermometer to ensure foods, especially meat, poultry, and eggs, are cooked to their correct internal temperature to destroy harmful bacteria.
Chill Foods Promptly: Refrigerate perishable items and leftovers within two hours to inhibit the rapid growth of bacteria that cause food poisoning.
Recognize the Symptoms: Common symptoms of foodborne illness include diarrhea, vomiting, and abdominal cramps, with variations depending on the specific pathogen involved.
Be Aware of High-Risk Foods: Be extra careful when handling foods commonly associated with pathogens, such as unpasteurized dairy, undercooked ground beef, poultry, and ready-to-eat deli meats.

Understanding the "Big 6" Foodborne Pathogens

Foodborne illness, also known as food poisoning, is a significant public health concern globally. Health agencies highlight a specific group of microbes, often called the "Big 6," due to their high infectivity and potential for severe symptoms. These pathogens are frequently transmitted through contaminated food, particularly via infected food handlers, posing risks in various food preparation environments. Understanding these common culprits is fundamental to practicing effective food safety.

The Six Key Foodborne Pathogens

1. Norovirus

Norovirus is a highly contagious virus that is the leading cause of foodborne illness in the U.S. It causes acute gastroenteritis with symptoms like vomiting and diarrhea. Norovirus spreads easily through contaminated food, water, person-to-person contact, and contact with contaminated surfaces. Prevention focuses on strict hand hygiene and surface disinfection.

2. Salmonella (nontyphoidal)

Nontyphoidal Salmonella is a bacterium commonly found in animal intestines. It causes fever, diarrhea, and cramps, and can be severe in vulnerable individuals. Common sources include undercooked poultry, eggs, and meat. Preventing infection involves proper cooking, avoiding cross-contamination, and handwashing.

3. Shiga toxin-producing E. coli (STEC)

STEC, such as E. coli O157:H7, is a bacterium known for causing severe, sometimes bloody, diarrhea and abdominal pain. It can lead to Hemolytic Uremic Syndrome (HUS), a serious kidney complication. Sources often include undercooked ground beef and unpasteurized products. Prevention includes thoroughly cooking ground beef and washing produce.

4. Hepatitis A Virus

Hepatitis A is a viral liver illness. Though spread through the fecal-oral route, it's considered foodborne when linked to contaminated food or water, often by infected food handlers. Symptoms include fatigue, jaundice, and nausea. Vaccination and diligent handwashing by food handlers are key preventive measures.

5. Shigella spp.

Shigella bacteria cause shigellosis, marked by fever, diarrhea (often bloody), and cramps. It's highly contagious with a low infectious dose and spreads through contaminated food or person-to-person contact. Sources include ready-to-eat foods handled by infected individuals. Strict handwashing is vital for prevention.

6. Campylobacter spp.

Campylobacter is a leading bacterial cause of diarrheal illness globally. Infection causes fever, cramps, and diarrhea, often linked to raw or undercooked poultry and unpasteurized milk. Prevention involves cooking poultry properly and avoiding unpasteurized dairy.

Comparison of the "Big 6" Foodborne Pathogens


Pathogen	Primary Source	Typical Symptoms	Incubation Period	Prevention Key
Norovirus	Ready-to-eat food, contaminated water, shellfish	Vomiting, watery diarrhea, nausea, abdominal cramps	12 to 48 hours	Hand hygiene, surface sanitation
Nontyphoidal Salmonella	Raw or undercooked poultry, eggs, meat	Fever, cramps, diarrhea, vomiting	6 to 72 hours	Proper cooking, prevent cross-contamination
*STEC (E. coli)*	Undercooked ground beef, unpasteurized products, produce	Bloody diarrhea, severe cramps, low fever	2 to 10 days	Cook beef thoroughly, wash produce
Hepatitis A Virus	Infected food handlers, contaminated seafood/water	Fatigue, jaundice, nausea, abdominal pain	2 to 7 weeks	Vaccination, strict food handler hygiene
Shigella spp.	Contaminated ready-to-eat foods, infected individuals	Fever, bloody diarrhea, abdominal cramps	1 to 3 days	Handwashing, proper sanitation
Campylobacter spp.	Raw or undercooked poultry, unpasteurized milk	Diarrhea (sometimes bloody), fever, abdominal cramps	2 to 5 days	Cook poultry thoroughly, use pasteurized milk

Essential Food Safety Practices

Protecting against these pathogens involves adhering to fundamental food safety guidelines:

Clean: Wash hands and surfaces regularly with soap and water.
Separate: Prevent cross-contamination by keeping raw meats away from other foods and using separate cutting boards.
Cook: Ensure foods reach safe internal temperatures using a thermometer.
Chill: Refrigerate perishable foods promptly.

By understanding these key foodborne pathogens and implementing these critical safety measures, individuals can significantly lower their risk of illness, benefiting both households and the wider community. These practices are crucial in both commercial and home kitchens.

Conclusion

The "Big 6" foodborne pathogens – Norovirus, Nontyphoidal Salmonella, STEC, Hepatitis A, Shigella, and Campylobacter – are major contributors to foodborne illnesses globally. While varied in origin and symptoms, consistent food handling vigilance is a common defense. Adopting strict hygiene, preventing cross-contamination, thorough cooking, and proper chilling are vital steps against these microscopic threats. Informed and cautious food practices are essential for personal and family health.

Visit FoodSafety.gov for additional food safety information

Frequently Asked Questions

Nontyphoidal Salmonella causes gastroenteritis (food poisoning) and is widespread, often linked to poultry and eggs. Salmonella Typhi causes typhoid fever, a much more severe, life-threatening systemic illness.

Yes, proper cooking to a safe internal temperature is one of the most effective ways to kill many foodborne pathogens, including Salmonella, E. coli, and Campylobacter. However, some toxins produced by bacteria like Staphylococcus aureus can be heat-resistant.

Norovirus and Hepatitis A Virus are two of the pathogens on the "Big 6" list that are viruses. The others are bacteria.

Norovirus is estimated by the CDC to be the most common cause of foodborne illness in the United States, responsible for millions of cases each year.

Food handlers can prevent the spread of these pathogens by practicing strict hand hygiene, not working while sick with gastrointestinal symptoms, and preventing cross-contamination during food preparation.

Hemolytic Uremic Syndrome (HUS) is a severe complication that can cause kidney failure, most often seen after infection with Shiga toxin-producing E. coli (STEC).

While Listeria is a very dangerous foodborne pathogen, the "Big 6" list, specifically for highly infectious pathogens typically transmitted by food handlers, does not include Listeria. However, some other official lists or surveillance systems may include Listeria as a major concern.