Pathogen Reference — Foodborne Illness Index

A reference guide to the pathogens and toxins covered on the ServSafe Manager exam — organized around the Big 6, the six pathogens you need to know cold, followed by the rest of the organisms and toxins you’re responsible for.

1. Master Table

Category	Organism / Toxin	Illness	Classification	Big 6?
Bacteria	Nontyphoidal Salmonella	Salmonellosis	Infection	Yes
Bacteria	Salmonella Typhi	Typhoid fever	Infection	Yes
Bacteria	Shigella spp.	Shigellosis	Infection	Yes
Bacteria	Shiga toxin-producing E. coli (STEC)	Hemorrhagic colitis	Toxin-mediated infection	Yes
Virus	Hepatitis A	Hepatitis A	Infection	Yes
Virus	Norovirus	Norovirus gastroenteritis	Infection	Yes
Bacteria	Bacillus cereus	B. cereus gastroenteritis	Intoxication	No
Bacteria	Listeria monocytogenes	Listeriosis	Infection	No
Bacteria	Clostridium perfringens	C. perfringens gastroenteritis	Toxin-mediated infection	No
Bacteria	Clostridium botulinum	Botulism	Intoxication	No
Bacteria	Campylobacter jejuni	Campylobacteriosis	Infection	No
Bacteria	Staphylococcus aureus	Staphylococcal gastroenteritis	Intoxication	No
Bacteria	Vibrio vulnificus / V. parahaemolyticus	Vibrio gastroenteritis / primary septicemia	Infection	No
Parasite	Anisakis simplex	Anisakiasis	Infection	No
Parasite	Cryptosporidium parvum	Cryptosporidiosis	Infection	No
Parasite	Giardia duodenalis	Giardiasis	Infection	No
Parasite	Cyclospora cayetanensis	Cyclosporiasis	Infection	No
Toxin	Histamine	Scombroid poisoning	Intoxication	No
Toxin	Ciguatoxin	Ciguatera fish poisoning	Intoxication	No
Toxin	Saxitoxin	Paralytic shellfish poisoning (PSP)	Intoxication	No
Toxin	Brevetoxin	Neurotoxic shellfish poisoning (NSP)	Intoxication	No
Toxin	Domoic acid	Amnesic shellfish poisoning (ASP)	Intoxication	No

Classification follows three categories: infection (a live pathogen is eaten and grows in the body), intoxication (a toxin is already present in the food before it’s eaten), and toxin-mediated infection (a live pathogen is eaten and produces its toxin inside the body).

2. The Big 6 (know these cold)

Every exam-prep source checked — ServSafe’s own materials, third-party practice tests, and instructor flashcard sets — names the same six pathogens as the most heavily and consistently tested, and the six an exam question will expect immediate, confident recall on: mandatory exclusion of a diagnosed food handler, correct food source, correct symptoms.

Nontyphoidal Salmonella (SAL-me-NEL-uh) — Salmonellosis

Naturally carried by many farm animals. Eating only a small amount can make a person sick; severity depends on the health of the person and the amount eaten.

• Foods: Poultry and eggs. Meat. Milk and dairy products. Produce, such as tomatoes, peppers, and cantaloupes.
• Symptoms: Diarrhea. Abdominal cramps. Vomiting. Fever.
• Prevention: Cook poultry and eggs to minimum internal temperatures. Prevent cross-contamination between poultry and ready-to-eat food. Keep food handlers who are vomiting, have diarrhea, or have been diagnosed with an illness from nontyphoidal Salmonella out of the operation.

Salmonella Typhi (SAL-me-NEL-uh Ti-fee) — Typhoid fever

Lives only in humans. People with typhoid fever carry the bacteria in their bloodstream and intestinal tract. Severity depends on the health of the person and the amount of bacteria eaten.

• Foods: Ready-to-eat food. Beverages.
• Symptoms: High fever. Weakness. Abdominal pain. Headache. Loss of appetite. Rash.
• Prevention: Exclude food handlers diagnosed with an illness caused by Salmonella Typhi. Wash hands. Cook food to minimum internal temperatures. Prevent cross-contamination.

Shigella spp. (shi-GEL-uh) — Shigellosis

Found in the feces of infected people. Most illnesses occur from eating or drinking contaminated food or water; flies can also transfer it. High levels remain in feces for weeks after symptoms end.

• Foods: Food easily contaminated by hands — salads containing TCS food (potato, tuna, shrimp, macaroni, chicken). Food that has contacted contaminated water, such as produce.
• Symptoms: Bloody diarrhea. Abdominal pain and cramps. Fever (occasionally).
• Prevention: Exclude food handlers who have diarrhea or have been diagnosed with an illness caused by Shigella. Wash hands. Control flies inside and outside the operation. Practice personal hygiene.

Shiga toxin-producing Escherichia coli (STEC) (ess-chur-EE-kee-UH KO-LI), including O157:H7, O26:H7, O26:H11, O111:H8, and O158:NM — Hemorrhagic colitis

Found in the intestines of cattle and infected people. Contaminates meat during slaughtering. Eating only a small amount can make a person sick. Produces toxins in the intestines after ingestion, causing illness.

• Foods: Ground beef (raw and undercooked). Contaminated produce.
• Symptoms: Diarrhea (eventually becomes bloody). Abdominal cramps. Kidney failure in severe cases.
• Prevention: Cook food, especially ground beef, to minimum internal temperatures. Purchase produce from approved, reputable suppliers. Prevent cross-contamination between raw meat and ready-to-eat food. Keep staff with diarrhea, and staff diagnosed with hemorrhagic colitis, out of the operation. Control time and temperature.

Hepatitis A (HEP-a-TI-tiss) — Hepatitis A

Mainly found in the feces of infected people. Contaminates water and many types of food, commonly ready-to-eat food and shellfish from contaminated water. A small amount can make a person sick; an infected person may show no symptoms for weeks but be very infectious. Cooking does not destroy it.

• Foods: Ready-to-eat food. Shellfish from contaminated water.
• Symptoms: Mild fever. General weakness. Nausea. Abdominal pain. Jaundice (appears later).
• Prevention: Exclude food handlers diagnosed with hepatitis A, or with jaundice for seven days or less. Wash hands. Avoid bare-hand contact with ready-to-eat food. Purchase shellfish from approved, reputable suppliers. Practice personal hygiene.

Norovirus (NOR-o-VI-rus) — Norovirus gastroenteritis

Commonly linked with ready-to-eat food; also linked to contaminated water. Extremely contagious — a small amount can cause illness, and people become contagious within hours of eating it. Virus persists in feces for days after symptoms end.

• Foods: Ready-to-eat food. Shellfish from contaminated water.
• Symptoms: Vomiting. Diarrhea. Nausea. Abdominal cramps.
• Prevention: Exclude food handlers who are vomiting, have diarrhea, or have been diagnosed with Norovirus. Wash hands. Avoid bare-hand contact with ready-to-eat food. Purchase shellfish from approved, reputable suppliers. Practice personal hygiene.

3. Other ServSafe-Tested Bacteria

Not part of the Big 6, but confirmed present across ServSafe study materials and practice questions — regularly tested, just not subject to the mandatory-exclusion emphasis the Big 6 get.

Bacillus cereus (ba-SIL-us SEER-ee-us) — B. cereus gastroenteritis

Spore-forming bacteria found in dirt. Produces two different toxins when allowed to grow to high levels, causing two distinct illness patterns.

• Foods: Diarrhea illness — cooked vegetables, meat products, milk. Vomiting illness — cooked rice dishes, including fried rice and rice pudding.
• Symptoms: Diarrhea illness — watery diarrhea, no vomiting. Vomiting illness — nausea, vomiting.
• Prevention: Cook food to minimum internal temperatures. Hold food at correct temperatures. Cool food correctly. Control time and temperature.

Listeria monocytogenes (liss-TEER-ee-uh MON-o-SI-TAHJ-uh-neez) — Listeriosis

Found in dirt, water, and plants. Unlike other bacteria, it grows in cool, moist environments. Uncommon in healthy people, but high-risk populations — particularly pregnant women — are especially vulnerable.

• Foods: Raw meat. Unpasteurized dairy products. Ready-to-eat food, such as deli meat, hot dogs, and soft cheeses.
• Symptoms: Pregnant women — miscarriage. Newborns — sepsis, pneumonia, meningitis.
• Prevention: Throw out any product past its use-by or expiration date. Cook raw meat to minimum internal temperatures. Prevent cross-contamination between raw/undercooked food and ready-to-eat food. Avoid unpasteurized dairy products. Control time and temperature.

Clostridium perfringens — C. perfringens gastroenteritis

Found in dirt, where it forms spores that allow it to survive; also carried in the intestines of animals and humans. Does not grow at refrigeration temperatures but grows rapidly in the Temperature Danger Zone. People who get sick usually don’t have nausea, fever, or vomiting.

• Foods: Meat. Poultry. Dishes made with meat and poultry, such as stews and gravies.
• Symptoms: Diarrhea. Severe abdominal pain.
• Prevention: Cool and reheat food correctly. Hold food at correct temperatures. Control time and temperature.

Clostridium botulinum (klos-TRID-ee-um BOT-chew-LINE-um) — Botulism

Forms spores often found in water and dirt, which can contaminate almost any food. Doesn’t grow well in refrigerated or highly acidic food, or food with low moisture — but grows without oxygen and produces a lethal toxin when food is time-temperature abused. Without medical treatment, death is likely.

• Foods: Incorrectly canned food. Reduced-oxygen packaged (ROP) food. Temperature-abused vegetables, such as baked potatoes. Untreated garlic-and-oil mixtures.
• Symptoms: Initially — nausea and vomiting. Later — weakness, double vision, difficulty speaking and swallowing.
• Prevention: Hold, cool, and reheat food correctly. Inspect canned food for damage. Control time and temperature.

Campylobacter jejuni (Camp-ee-lo-BAK-ter jay-JUNE-ee) — Campylobacteriosis

Commonly associated with poultry but has also contaminated water. Illness often occurs when poultry is incorrectly cooked or raw poultry cross-contaminates other food and food-contact surfaces.

• Foods: Poultry. Water contaminated with the bacteria. Meats. Stews/gravies.
• Symptoms: Diarrhea (may be watery or bloody). Abdominal cramps. Fever. Vomiting. Headaches.
• Prevention: Cook food, particularly poultry, to required minimum internal temperatures. Prevent cross-contamination between raw poultry and ready-to-eat food. Control time and temperature.

Staphylococcus aureus (STAF-uh-lo-KOK-us OR-ee-us) — Staphylococcal gastroenteritis

Found on humans — particularly hair, nose, throat, and infected cuts. Transferred to food by unwashed hands. Once grown to large numbers, produces toxins that cooking cannot destroy.

• Foods: Food that requires handling during prepping. Salads containing TCS food (egg, tuna, chicken, macaroni). Deli meat.
• Symptoms: Nausea. Vomiting and retching. Abdominal cramps.
• Prevention: Wash hands, particularly after touching hair, face, or body. Cover wounds on hands and arms. Hold, cool, and reheat food correctly. Practice personal hygiene.

Vibrio vulnificus and Vibrio parahaemolyticus (VIB-ree-o vul-NIF-ih-kus / PAIR-uh-HEE-mo-lit-ih-kus) — Vibrio gastroenteritis / V. vulnificus primary septicemia

Found in the waters where shellfish are harvested. Grow very rapidly in the mid-range of the Temperature Danger Zone. People with chronic conditions (diabetes, cirrhosis) risk primary septicemia, which can be fatal.

• Foods: Oysters from contaminated water.
• Symptoms: Diarrhea. Abdominal cramps and nausea. Vomiting. Low-grade fever and chills.
• Prevention: Cook oysters to minimum internal temperatures. Purchase from approved, reputable suppliers.

4. Parasites (ServSafe-Tested)

Anisakis simplex (ANN-ih-SAHK-iss SIM-plex) — Anisakiasis

People get sick eating raw or undercooked fish containing this parasite.

• Foods: Raw and undercooked fish — herring, cod, halibut, mackerel, Pacific salmon.
• Symptoms: Tingling in throat. Coughing up worms.
• Prevention: Cook fish to minimum internal temperatures. If serving raw or undercooked fish, purchase sushi-grade fish that has been frozen to the correct time-temperature requirements. Purchase from approved, reputable suppliers.

Cryptosporidium parvum (KRIP-TOH-spor-ID-ee-um PAR-vum) — Cryptosporidiosis

Found in the feces of infected people. Food handlers transfer it via unwashed hands. Day-care and medical settings see frequent person-to-person spread. More severe in people with weakened immune systems.

• Foods: Contaminated water. Produce.
• Symptoms: Watery diarrhea. Abdominal cramps. Nausea. Weight loss.
• Prevention: Use correctly treated water. Keep food handlers with diarrhea out of the operation. Wash hands. Purchase from approved, reputable suppliers.

Giardia duodenalis (jee-ARE-dee-uh do-WAH-den-AL-is), also known as G. lamblia or G. intestinalis — Giardiasis

Found in the feces of infected people. Food handlers transfer it via unwashed hands.

• Foods: Incorrectly treated water. Produce.
• Symptoms: Initially — fever. Later — diarrhea, abdominal cramps, nausea.
• Prevention: Use correctly treated water. Keep food handlers with diarrhea out of the operation. Wash hands. Purchase from approved, reputable suppliers.

Cyclospora cayetanensis (SI-klo-spor-uh KI-uh-te-NEN-sis) — Cyclosporiasis

Found in contaminated water and associated with produce irrigated or washed with it; also in the feces of infected people.

• Foods: Incorrectly treated water. Produce, such as berries, lettuce, or basil.
• Symptoms: Nausea. Abdominal cramps. Mild fever. Diarrhea alternating with constipation. Loss of weight. Loss of appetite.
• Prevention: Purchase produce from approved, reputable suppliers. Keep food handlers with diarrhea out of the operation. Wash hands.

5. Toxins (ServSafe-Tested)

Histamine (HISS-ta-meen) — Scombroid poisoning

Occurs when high levels of histamine build up in scombroid and other fish species. Forms when fish are time-temperature abused; not destroyed by freezing, cooking, smoking, or curing.

• Foods: Tuna. Bonito. Mackerel. Mahimahi.
• Symptoms: Initially — reddening of the face and neck, sweating, headache, burning/tingling sensation in the mouth or throat. Possibly later — diarrhea, vomiting.
• Prevention: Prevent time-temperature abuse during storage and prepping. Purchase from approved, reputable suppliers.

Ciguatoxin (SIG-wa-TOX-in) — Ciguatera fish poisoning

Found in marine algae; builds up in fish that eat smaller fish that ate the toxic algae. Cannot be detected by smell or taste, and is not eliminated by cooking or freezing. Symptoms may last months to years.

• Foods: Predatory tropical reef fish from the Pacific, western Indian Ocean, and Caribbean — barracuda, grouper, jacks, snapper.
• Symptoms: Reversal of hot and cold sensations. Nausea. Vomiting. Tingling in fingers, lips, or toes. Joint and muscle pain.
• Prevention: Purchase predatory tropical reef fish from approved, reputable suppliers.

Saxitoxin (SAX-ih-TOX-in) — Paralytic shellfish poisoning (PSP)

Shellfish become contaminated by filtering toxic algae from the water. Cannot be smelled or tasted; not destroyed by cooking or freezing. Death from paralysis possible at high toxin levels.

• Foods: Shellfish found in colder waters (Pacific, New England) — clams, mussels, oysters, scallops.
• Symptoms: Numbness. Tingling of the mouth, face, arms, and legs. Dizziness. Nausea. Vomiting. Diarrhea.
• Prevention: Purchase shellfish from approved, reputable suppliers.

Brevetoxin (BREV-ih-TOX-in) — Neurotoxic shellfish poisoning (NSP)

Same filter-feeding contamination mechanism as saxitoxin. Cannot be smelled or tasted; not destroyed by cooking or freezing.

• Foods: Shellfish found in warmer waters (west coast Florida, Gulf of Mexico, Caribbean) — clams, mussels, oysters.
• Symptoms: Tingling and numbness of the lips, tongue, and throat. Dizziness. Reversal of hot and cold sensations. Vomiting. Diarrhea.
• Prevention: Purchase shellfish from approved, reputable suppliers.

Domoic acid (duh-MO-ik) — Amnesic shellfish poisoning (ASP)

Same filter-feeding contamination mechanism. Severity depends on toxin dose and the health of the person. Cannot be smelled or tasted; not destroyed by cooking or freezing.

• Foods: Shellfish found in the coastal waters of the Pacific Northwest and eastern Canada — clams, mussels, oysters, scallops.
• Symptoms: Initially — vomiting, diarrhea, abdominal pain. Possibly later — confusion, memory loss, disorientation, seizure, coma.
• Prevention: Purchase shellfish from approved, reputable suppliers.