Food Handler Training — Module 2: Foodborne Illnesses & Pathogens

Know Your Enemy

Foodborne pathogens are invisible. They don't change how food looks, smells, or tastes. That's what makes them dangerous — by the time someone gets sick, the contaminated food is long gone. Your job is to stop them before they reach the plate.

For the exam, you need to know the Big 6 bacterial pathogens cold. Onset times, symptoms, how they spread, and — critically — what makes each one unique. The exam loves to test the differences between them, because that's where people get confused.

The Big 6 Bacteria

1. Salmonella

The poster child of poultry contamination. Salmonella lives in the intestinal tract of chickens, and contamination during slaughter is a constant risk at any processing plant.

• Sources: Raw poultry (most common), raw eggs, raw meat, unpasteurized milk
• Onset: 6 hours to 6 days
• Symptoms: Watery or bloody diarrhea, stomach cramps, headache, nausea, vomiting, fever
• Duration: 4-7 days
• Prevention: Cook poultry to 74°C (165°F) internal temperature

2. E. coli O157:H7 (STEC)

This one is the ground beef nightmare. Surface bacteria on a whole cut of beef sit on the outside, where searing kills them. But when you grind that beef, those surface bacteria get mixed throughout the entire product. That's why ground beef has a higher minimum cooking temperature than a steak.

• Sources: Undercooked ground beef, raw milk, contaminated produce, contaminated water
• Onset: 2-5 days
• Symptoms: Severe bloody diarrhea, stomach cramps, vomiting
• Duration: 5-10 days
• Complications: Hemolytic uremic syndrome (HUS) — can cause kidney failure, especially in children
• Prevention: Cook ground beef to 71°C (160°F)

3. Listeria monocytogenes

Listeria is the slow killer. While most bacteria need warmth to multiply, Listeria grows at refrigeration temperatures. Read that again. Your fridge doesn't stop it. This is what makes it uniquely dangerous in ready-to-eat (RTE) deli meats, hot dogs, and smoked products.

• Sources: RTE deli meats, hot dogs, soft cheeses, smoked seafood
• Onset: 1-4 weeks (extremely long incubation)
• Symptoms: Fever, muscle aches, nausea, diarrhea; can cause meningitis in severe cases
• High-risk groups: Pregnant women (can cause miscarriage or stillbirth), elderly, immunocompromised
• Prevention: Proper sanitation of all equipment, preventing cross-contamination with RTE foods

4. Campylobacter jejuni

If you work with chicken, this is your number one bacterial threat. Campylobacter is the most common bacterial cause of foodborne illness in Canada — and raw or undercooked poultry is the most common source. It lives naturally in the GI system of healthy birds. The chickens look perfectly fine. The bacteria are there anyway.

• Sources: Raw/undercooked poultry (most common), raw milk, contaminated water
• Onset: 2-5 days
• Symptoms: Bloody diarrhea, fever, stomach cramps, nausea, vomiting
• Duration: About 1 week
• Prevention: Cook poultry thoroughly to 74°C; prevent cross-contamination from raw poultry juices

5. Clostridium perfringens

Known as the "cafeteria germ." Outbreaks happen when large batches of meat, poultry, or gravy are cooked and then held at improper temperatures. The catch: C. perfringens forms spores that survive cooking. So even after you've cooked the food, if you let it cool slowly through the danger zone, the spores germinate and the bacteria multiply rapidly.

• Sources: Meat, poultry, gravies — especially large batches held improperly
• Onset: 6-24 hours
• Symptoms: Intense abdominal cramps, watery diarrhea
• Duration: Usually less than 24 hours
• Prevention: Keep hot food above 60°C; cool cooked food rapidly using the two-stage method

6. Staphylococcus aureus

Staph is the fast one. Symptoms can start as quickly as 30 minutes after eating contaminated food. But here's what makes it truly dangerous: Staph produces a heat-stable toxin. Cooking kills the bacteria, but the toxin it already produced stays in the food. Once the toxin is there, no amount of reheating will make it safe.

• Sources: Foods handled by workers with infected wounds, skin infections, or who carry the bacteria in their nose
• Onset: 30 minutes to 8 hours (fastest of the Big 6)
• Symptoms: Nausea, vomiting, stomach cramps, diarrhea
• Prevention: Personal hygiene, covering all wounds, not working while ill

Key Viruses

Norovirus

The most common cause of foodborne illness overall — more common than any single bacteria. Extremely contagious. One critical fact for the exam: alcohol-based hand sanitizers do NOT kill Norovirus. You must use soap and water.

• Sources: Contaminated food/water, person-to-person contact, contaminated surfaces
• Onset: 12-48 hours
• Symptoms: Vomiting, diarrhea, nausea, stomach pain
• Prevention: Handwashing with soap and water, excluding ill workers, proper sanitation

Hepatitis A

Very long incubation period — 15 to 50 days. By the time symptoms appear, the infected person has been working (and potentially contaminating food) for weeks. Hepatitis A is a reportable disease. A food handler diagnosed with it must be immediately excluded from work.

• Onset: 15-50 days
• Symptoms: Jaundice (yellowing of skin and eyes), fatigue, abdominal pain, nausea

Campylobacter and Salmonella: The Two Biggest Chicken Threats

If you process poultry, these two bacteria define your daily risk. Campylobacter is the most common bacterial cause of foodborne illness in Canada. Salmonella is the most common cause of hospitalization from foodborne illness. Both are naturally present in healthy chickens. Both contaminate product during slaughter and processing.

The difference between a safe product and a recall often comes down to three things: proper cooking temperatures (74°C for chicken pieces), preventing cross-contamination between raw and cooked product, and rigorous equipment sanitation between production runs.

Real CFIA Recalls (2024-2025)

These aren't hypothetical scenarios. In the 2024-25 fiscal year, CFIA issued 139 food recalls. Of those, 89 were higher-risk. Nearly half were discovered through CFIA's own sampling — meaning the companies didn't catch the problems themselves.

• Kingwuu/T&T Kitchen brands (April 2024): Meat and vegetable products recalled for Listeria monocytogenes
• One World Foods Cajun BBQ Chicken Burgers (April 2024): Recalled for undeclared egg and soy — an allergen failure in a chicken product
• BrucePac (October 2024): Massive recall of approximately 11.8 million pounds of RTE meat and poultry for Listeria — affected products at Trader Joe's, Aldi, Boston Market, and others

11.8 million pounds. One Listeria failure. That's what's at stake.

Three Types of Food Hazards

The exam categorizes food hazards into three types. You need to know all three and be able to give examples of each.

Biological hazards — bacteria, viruses, parasites, fungi. This is the most common cause of foodborne illness. Everything we've covered above falls here.

Chemical hazards — cleaning agents, sanitizers, pesticides, lubricants, toxic metals. In a processing plant, this means sanitizer residue left on equipment, over-concentrated cleaning solutions, or non-food-grade lubricants on machinery.

Physical hazards — glass, metal fragments, bone chips, hair, bandages, jewelry, staples. In a chicken processing plant, bone fragments and metal shavings from cutting equipment are the most common physical hazards. This is why metal detectors on production lines and strict jewelry policies exist.