Foodborne Illnesses

A pathogen is a microorganism that causes disease. Not all illnesses work the same way, and the difference matters for prevention.

• Infection — you eat live pathogens that then multiply in your body (for example Salmonella). Symptoms usually appear hours to days later.
• Intoxication — you eat a toxin the pathogen already produced in the food (for example Staphylococcus aureus or Bacillus cereus). Symptoms can start within 1 to 6 hours, and cooking does not destroy most of these toxins.
• Toxin-mediated infection — you eat live pathogens that then produce toxins inside your body (for example E. coli STEC and Shigella).
• Some pathogens need only a very small dose to cause illness — as few as 10 to 100 cells for Shigella or STEC — which is why 'just a little' contamination still matters.
• Viruses (such as Norovirus and Hepatitis A) do not grow in food; they simply need to be transferred to it, usually by an infected person's hands.

Bacteria need six conditions to multiply. You cannot control all of them, but controlling time and temperature is almost always within your reach.

• F — Food: bacteria need nutrients, especially protein and carbohydrate.
• A — Acidity: they grow best in food with a pH between 4.6 and 7.5 (slightly acidic to neutral).
• T — Temperature: they grow fastest inside the temperature danger zone, 41°F to 135°F.
• T — Time: given enough time in the danger zone, bacteria can double roughly every 20 minutes.
• O — Oxygen: some need it, some (like Clostridium botulinum) grow without it — which is why vacuum-packed and canned goods carry their own risks.
• M — Moisture: measured as water activity (aw); most bacteria need an aw above 0.85, which is why dried and salted foods keep longer.

Six pathogens are considered so contagious and so severe that a diagnosis must always be reported to management and the food handler removed from work.

• The Big 6 pathogens must always be reported to a manager: Norovirus, Hepatitis A, non-typhoidal Salmonella, Salmonella Typhi, Shigella spp., and Shiga toxin-producing E. coli (STEC).
• Norovirus — the leading cause of foodborne illness outbreaks in the U.S. Extremely contagious, spread by the fecal-oral route, and not killed by most standard sanitizer concentrations; vomit and diarrhea events require a special clean-up procedure.
• Hepatitis A — a virus that attacks the liver and can cause jaundice. A person can be contagious for weeks before symptoms appear, and it is commonly linked to ready-to-eat food and shellfish.
• Salmonella Typhi — causes typhoid fever, linked to ready-to-eat food and beverages; non-typhoidal Salmonella is linked to poultry, eggs, dairy and produce.
• Shigella spp. — spread by flies and by hands contaminated with feces; often linked to ready-to-eat food and salads made with contact.
• Shiga toxin-producing E. coli (STEC) — linked to ground beef and contaminated produce; can cause bloody diarrhea and kidney failure (HUS), especially in children.

Some foods support pathogen growth far better than others, and some guests get far sicker from the same dose.

• TCS foods (Time/Temperature Control for Safety) — such as meat, poultry, seafood, dairy, eggs, cooked rice and pasta, cut leafy greens, cut tomatoes, cut melons, sprouts, tofu, garlic-in-oil mixtures and untreated baked potatoes — support rapid pathogen growth and need extra care.
• Ready-to-eat (RTE) food is food that will be eaten without further cooking — salads, bread, garnishes, cooked food that has cooled. RTE food gets no 'kill step', so contamination reaches the guest directly.
• Highly susceptible populations — young children, older adults, pregnant people and anyone with a weakened immune system — face a much higher risk of severe illness.
• Establishments serving these groups (hospitals, nursing homes, daycare, schools) face stricter rules, including bans on raw or undercooked animal products and unpasteurized items.
• Common symptoms include nausea, vomiting, diarrhea, and fever, though some infections like Hepatitis A can take weeks to appear.