TL;DR

The "Big Six" are six highly contagious foodborne pathogens that food handlers must report to their manager if diagnosed with them. Food handlers must also report key symptoms — especially vomiting, diarrhea, jaundice, sore throat with fever, or infected wounds — even before a diagnosis. Per the FDA Food Code, the Big Six are: Norovirus, Salmonella Typhi (typhoid fever), Shigella species, Hepatitis A virus, Shiga toxin-producing E. coli (STEC) including E. coli O157:H7, and Nontyphoidal Salmonella. These six are singled out because they spread easily through food handlers, cause significant illness in customers, and have specific public health implications. The core rules for food handlers: report symptoms (especially vomiting, diarrhea, jaundice, sore throat with fever, or open wounds), stay home or be excluded from work when sick with these pathogens, and only return to work after the required exclusion period (typically when symptom-free for 24 hours plus, in some cases, medical clearance). Knowing the names, primary symptoms, common food sources, and reporting/exclusion rules for each is essential food handler exam material.

What "The Big Six" Means

The FDA Food Code identifies six pathogens — four bacterial categories and two viruses — that pose particularly high risks in food service settings. These pathogens were grouped together because they all:

  1. Spread easily through food contaminated by infected food handlers
  2. Cause significant illness that can lead to hospitalization or death in vulnerable populations
  3. Have specific reporting requirements to public health authorities
  4. May require exclusion or restriction from food handling until symptom-free and, for some diagnoses, medically cleared under local health rules

The "Big Six" designation comes from FDA Food Code Section 2-201.11 and related provisions. Food handler training programs (ServSafe, state food handler programs, county health department training) all teach the Big Six because they're the legally-defined reportable illnesses food handlers must know.

Note on terminology: Some materials refer to a "Big Five" or "Big Seven" depending on whether they group Salmonella Typhi separately from Nontyphoidal Salmonella, or whether they include additional pathogens. The standard current terminology in most US food handler training is the "Big Six" with the list below.

The Six Pathogens

1. Norovirus

Type: Virus Common name: "Stomach flu" (a misnomer — Norovirus is unrelated to influenza) Primary symptoms: Sudden onset of vomiting, diarrhea, nausea, stomach cramps, low-grade fever. Symptoms typically appear 12-48 hours after exposure and last 1-3 days. Transmission: Extremely contagious. Spread through the fecal-oral route, contaminated food or water, contact with infected surfaces, or close contact with infected people. As few as 10-100 viral particles can cause infection. Common food sources: Ready-to-eat foods touched by infected handlers (salads, sandwiches, fruits), shellfish from contaminated water, contaminated water itself. Why it's dangerous in food service: Norovirus is the leading cause of foodborne illness outbreaks in the United States, often traced to infected food handlers. It's highly resistant to alcohol-based sanitizers — soap and water handwashing is much more effective. Food handler implications: Must report vomiting/diarrhea symptoms. Must be excluded from work until symptom-free for at least 24-48 hours (jurisdictions vary).

2. Salmonella Typhi (Typhoid Fever)

Type: Bacterium (a specific Salmonella serotype) Distinguishing feature: Causes typhoid fever, a systemic illness — different from common Salmonella food poisoning Primary symptoms: Sustained high fever, abdominal pain, headache, weakness, sometimes a rash ("rose spots"). Symptoms develop gradually over 1-2 weeks after exposure. Transmission: Fecal-oral route. Humans are the only reservoir — infected people (including chronic carriers without obvious symptoms) shed the bacteria in stool and urine. Common food sources: Food or water contaminated by an infected food handler. Rare in the US but common in regions with poor sanitation. Why it's dangerous in food service: Some people become chronic carriers — they shed the bacteria for months or years without symptoms. The famous historical case "Typhoid Mary" was a cook who infected dozens of people while feeling healthy. Food handler implications: Must report a diagnosis, symptoms, or known exposure risk; managers may also ask about recent travel when typhoid exposure is a concern. Generally excluded from food handling until medical clearance proves they are no longer carriers (which can take many weeks).

3. Shigella Species

Type: Bacterium Distinguishing feature: Causes shigellosis (bacillary dysentery) Primary symptoms: Diarrhea (often bloody), fever, stomach cramps, sometimes vomiting. Symptoms appear 1-2 days after exposure and last 5-7 days. Transmission: Fecal-oral route. Very low infectious dose — as few as 10-100 bacteria can cause illness. Spread by contaminated food, water, or direct contact. Common food sources: Foods handled by infected workers, especially salads, sandwiches, raw vegetables, dairy products. Flies can also transmit it from contaminated surfaces. Why it's dangerous in food service: Like Norovirus, the infectious dose is very low, making infected food handlers a major outbreak risk. Bloody diarrhea symptoms are particularly recognizable. Food handler implications: Must report symptoms. Excluded until symptom-free and, in some cases, with negative stool tests showing the infection has cleared.

4. Hepatitis A Virus

Type: Virus Distinguishing feature: Causes liver inflammation; jaundice is a signature late symptom Primary symptoms: Initial flu-like symptoms (fatigue, fever, nausea) followed by jaundice (yellowing of skin and whites of eyes), dark urine, abdominal pain, and loss of appetite. Symptoms develop 15-50 days after exposure (long incubation period). Transmission: Fecal-oral route. Spread through contaminated food, water, or close contact with an infected person. An infected person is most contagious before symptoms develop. Common food sources: Foods handled by infected workers (especially ready-to-eat items), contaminated water, raw shellfish from contaminated waters. Why it's dangerous in food service: The long incubation period and pre-symptomatic shedding mean infected food handlers can transmit Hepatitis A for weeks before they realize they're sick. Outbreaks have caused hundreds of cases traced to single food handlers. Food handler implications: Must report any diagnosis of Hepatitis A or exposure to someone with Hepatitis A. Excluded from work until medical clearance. Vaccination is available and recommended for food handlers in many jurisdictions.

5. Shiga Toxin-Producing E. coli (STEC) — including E. coli O157:H7

Type: Bacterium (specific E. coli strains that produce Shiga toxin) Distinguishing feature: Most E. coli is harmless; STEC strains produce a dangerous toxin Primary symptoms: Severe stomach cramps, diarrhea (often bloody), vomiting, sometimes low fever. Symptoms appear 3-4 days after exposure and last 5-10 days. Can cause Hemolytic Uremic Syndrome (HUS) in severe cases — a kidney complication that can be fatal, especially in children and elderly. Transmission: Fecal-oral route. Most commonly from contaminated undercooked ground beef, but also from raw produce (lettuce, sprouts, spinach), unpasteurized dairy, and contaminated water. Common food sources: Undercooked ground beef, leafy greens, sprouts, unpasteurized milk and juice, contaminated water, and food handled by infected workers. Why it's dangerous in food service: Very low infectious dose. The link to undercooked ground beef means proper cooking temperatures for ground meat are critical. Cross-contamination between raw beef and other foods is a major outbreak source. Food handler implications: Must report symptoms, especially bloody diarrhea. Excluded from work until medical clearance.

6. Nontyphoidal Salmonella

Type: Bacterium (Salmonella serotypes other than Typhi) Distinguishing feature: Causes salmonellosis — the most common type of Salmonella food poisoning Primary symptoms: Diarrhea, fever, stomach cramps, sometimes vomiting. Symptoms appear 6-72 hours after exposure and last 4-7 days. Transmission: Most commonly through contaminated animal products (raw poultry, eggs, beef, dairy), but also through cross-contamination from raw to ready-to-eat foods and via infected food handlers. Common food sources: Raw poultry, raw eggs (including foods made with raw eggs like Caesar dressing or homemade mayonnaise), undercooked meat, contaminated produce, dairy products. Why it's dangerous in food service: Extremely common. Estimated to cause over 1 million cases of foodborne illness in the US annually. Proper cooking temperatures and cross-contamination prevention are the main controls. Food handler implications: Must report symptoms. Excluded or restricted according to local health rules; return to food handling may require being symptom-free and, for confirmed diagnoses, health-department or medical clearance.

What Food Handlers Must Do (Reporting and Exclusion Rules)

The FDA Food Code requires food handlers to report specific symptoms and diagnoses to their manager. The manager then determines whether to exclude the food handler from work or restrict their duties.

Symptoms food handlers must report:

Diagnoses food handlers must report:

Exclusion vs Restriction

The Food Code distinguishes between two responses:

Returning to Work

The standard return-to-work rules:

Common Exam Patterns

Pattern 1: Identifying the Big Six "Which of these is one of the 'Big Six' foodborne pathogens? (a) Listeria, (b) Norovirus, (c) Campylobacter, (d) Botulism" → Norovirus. The other choices are foodborne pathogens but are NOT part of the FDA Food Code "Big Six."

Pattern 2: Reporting requirements "A food handler comes to work with diarrhea. What should they do?" → Report the symptom to their manager immediately. The manager will determine whether to exclude them from work. Coming to work with diarrhea is a Big Six-related symptom and the food handler should not handle food.

Pattern 3: Jaundice and Hepatitis A "A food handler notices yellowing of their skin and eyes. What should they do?" → Report to their manager and seek medical attention immediately. Jaundice can indicate Hepatitis A and requires medical evaluation and work exclusion.

Pattern 4: Symptom-to-pathogen matching "A customer reports bloody diarrhea, severe cramps, and reports eating an undercooked hamburger 4 days ago. Which pathogen is most likely?" → Shiga toxin-producing E. coli (STEC), particularly E. coli O157:H7. The incubation period (3-4 days), bloody diarrhea, and association with undercooked ground beef are all consistent with STEC.

Pattern 5: Exclusion vs restriction "A food handler had Norovirus and has been symptom-free for 12 hours. Can they return to work?" → Not yet. The standard exclusion period for Norovirus is at least 24 hours (some jurisdictions require 48 hours) of being symptom-free.

Pattern 6: Highest-risk food handler scenario "Which of these scenarios poses the highest risk of a foodborne illness outbreak? (a) A food handler with a small cut on their finger, properly bandaged and gloved, (b) A food handler with diarrhea who feels well enough to work, (c) A food handler who didn't wash hands after smoking, (d) A food handler who reuses a cutting board for raw and cooked foods." → (b) is the most direct Big Six risk. While all are food safety concerns, an infected food handler with active diarrhea symptoms is the canonical Big Six scenario — multiple Big Six pathogens cause diarrhea and are highly contagious.

Common Misconceptions

  1. "If I feel a little sick, I should still work — managers don't want me calling out." False and dangerous. Working while showing Big Six symptoms is one of the primary causes of foodborne illness outbreaks. Report symptoms immediately. Many employers and jurisdictions have policies designed to encourage illness reporting; employees should follow workplace and local health-department procedures.
  2. "Hand sanitizer kills Norovirus." Largely false. Norovirus is highly resistant to alcohol-based sanitizers. Soap and water handwashing is much more effective.
  3. "Salmonella only comes from chicken." False. Salmonella can be transmitted through raw eggs, undercooked meat (any kind), unpasteurized dairy, contaminated produce, and infected food handlers. Chicken is a high-risk source but not the only one.
  4. "You can tell if you have food poisoning by the taste of the food." False. Most Big Six pathogens don't change food's appearance, smell, or taste. Time and temperature controls — and not infected food handling — are the only reliable controls.
  5. "If symptoms are mild, exclusion isn't needed." False. Many Big Six pathogens are highly contagious even with mild symptoms (or pre-symptomatic, as with Hepatitis A). Symptom severity doesn't determine the exclusion requirement — symptom type and pathogen diagnosis do.

Frequently Asked Questions

What are the Big Six foodborne pathogens?
The "Big Six" are six foodborne pathogens that the FDA Food Code identifies as requiring food handlers to report to their manager — if diagnosed with one of them, or if showing key symptoms even before a diagnosis. They are: Norovirus, Salmonella Typhi (typhoid fever), Shigella species, Hepatitis A virus, Shiga toxin-producing E. coli (STEC, including E. coli O157:H7), and Nontyphoidal Salmonella. These six are singled out because they spread easily through food handlers, cause significant illness, and have specific public health reporting requirements.
What symptoms must food handlers report to their manager?
Per the FDA Food Code, food handlers must report any of these symptoms to their manager: vomiting, diarrhea, jaundice (yellowing of skin or eyes), sore throat with fever, and any open wounds, sores, or boils on hands, wrists, or exposed body parts. They must also report any diagnosed Big Six infection, recent exposure to someone with a Big Six pathogen, or recent travel to areas with active foodborne illness outbreaks. The manager then determines whether to exclude the food handler from work or restrict their duties away from food contact.
How long must a food handler stay home with Norovirus?
Most jurisdictions require food handlers with Norovirus to remain away from food handling duties until they have been symptom-free (no vomiting or diarrhea) for at least 24 hours. Some jurisdictions require 48 hours symptom-free. Because Norovirus is highly contagious and can still shed for some time after symptoms end, some jurisdictions also require medical clearance before return to work. Always check the local health department requirements that apply to your operation. Food handlers should never return to work simply because they "feel better" — the exclusion period must be met.
What's the difference between Norovirus and food poisoning from Salmonella?
Both cause similar acute gastrointestinal symptoms (diarrhea, vomiting, cramps), but they're different pathogens with different sources and patterns. Norovirus is a virus, spread primarily by infected food handlers contaminating ready-to-eat foods or by contaminated water; it's the leading cause of US foodborne illness outbreaks. Nontyphoidal Salmonella is a bacterium, typically spread through contaminated animal products (especially raw poultry and eggs), undercooked meat, or cross-contamination. Both are part of the Big Six and require reporting and exclusion. Norovirus has a shorter incubation period (12-48 hours) than Salmonella (6-72 hours), and Norovirus is much more resistant to hand sanitizers than most bacteria.
Why is Hepatitis A on the Big Six list?
Hepatitis A is on the Big Six list because infected food handlers can transmit it for weeks before they show symptoms — the incubation period is 15-50 days, and infected people are most contagious before jaundice and other obvious symptoms appear. This pre-symptomatic transmission has caused major outbreaks traced to single food handlers infecting hundreds of customers. Hepatitis A is spread through the fecal-oral route, so infected handlers who don't wash hands properly after restroom use can contaminate ready-to-eat foods. Vaccination is available, and many jurisdictions recommend or require it for food handlers. The combination of long pre-symptomatic transmission and severe illness (liver inflammation) makes it particularly dangerous in food service.
Can food handlers work if they have a cold or flu?
The Big Six reporting requirements focus on gastrointestinal symptoms (vomiting, diarrhea), jaundice, sore throat with fever, and infected wounds — not common cold symptoms. A food handler with a runny nose, mild cough, and no fever generally can work, but they should wash hands frequently and use gloves when handling ready-to-eat foods. However, if a food handler has a fever with sore throat (which could indicate a contagious illness), they must report to their manager and may be excluded or restricted. Symptoms like vomiting, diarrhea, or jaundice — even in the absence of a confirmed diagnosis — require immediate reporting and likely exclusion from work pending evaluation.

Bottom Line

The "Big Six" foodborne pathogens — Norovirus, Salmonella Typhi, Shigella, Hepatitis A, STEC (E. coli O157:H7), and Nontyphoidal Salmonella — are the six pathogens food handlers must report; confirmed or suspected cases often require exclusion or restriction under local health rules. They share three characteristics: easy spread through food handlers, significant illness in customers, and specific public health implications. The core food handler responsibilities are: report symptoms (vomiting, diarrhea, jaundice, sore throat with fever, infected wounds) to the manager immediately; stay home or follow restrictions when sick; don't return until symptom-free for at least 24 hours (or medically cleared for specific pathogens, depending on local rules). Memorizing the six names, primary symptoms, common food sources, and reporting/exclusion rules is essential exam material — and essential for preventing outbreaks in real kitchen work. For more food safety topics, see our guides on temperature danger zone, handwashing — when and how, cross-contamination prevention, and the complete ServSafe Food Handler exam guide.

Source: FDA Food Code · CDC Food Safety · ServSafe (National Restaurant Association)