Food-Borne Illness and Intoxication

 FOOD-BORNE ILLNESS AND INTOXICATION

KEY DIFFERENCES: INFECTION VS INTOXICATION VS TOXICOINFECTION

Feature	Infection	Intoxication	Toxicoinfection
Live organism consumed?	Yes	No (toxin already in food)	Yes
Toxin formed in intestine?	Sometimes	No	Yes
Incubation	Longer (hours–days)	Very short (1–6 hrs in Staphylococcus aureus)	Moderate (8–24 hrs)
Example	Salmonella, Shigella	Staphylococcus aureus, Clostridium botulinum	Clostridium perfringens

BACTERIAL FOOD-BORNE ILLNESSES

A) Food-Borne Infection - Caused when viable (live) pathogenic bacteria are ingested and multiply in the intestine.

Pathogen	Source	Symptoms	Key Features
Salmonella spp.	Eggs, poultry, milk, meat	Diarrhea, fever, cramps	Survives refrigeration, killed by heat
Shigella spp.	Water, salads, raw vegetables	Dysentery, bloody stools	Low infectious dose
Vibrio cholerae	Seafood, contaminated water	Severe watery diarrhea	Toxin mediated; dehydration risk
Campylobacter jejuni	Meat, poultry, milk	Fever, cramping, diarrhea	Microaerophilic; 42°C optimum
Listeria monocytogenes	Dairy, meat, refrigerated foods	Fever, meningitis, miscarriage	Psychrotrophic (grows in fridge)

B) Food-Borne Intoxication - Disease caused by preformed toxins in food (organisms need not be alive when consumed).

Organism	Toxin	Food Sources	Characteristics
Staphylococcus aureus	Enterotoxin (resistant to heating and stomach enzymes)	Meat, cream pastries, salads	Heat-stable toxin; rapid vomiting (1-6 hrs)
Clostridium botulinum	Botulinum neurotoxin (destroyed by heating at 80 °C for 10 minutes)	Improper canned foods, sausages	Deadly; causes paralysis; anaerobic spore former
Bacillus cereus – Emetic type	Emetic toxin (Spores survive in improperly processed canned foods → germinate and produce toxin)	Fried rice, starch foods	Vomiting in 1–5 hrs; heat-stable
Bacillus cereus – Diarrheal type	Enterotoxin (Spores survive in improperly processed canned foods → germinate and produce toxin)	Milk, vegetables, meats	Diarrhea within 6–15 hrs

C) Food-Borne Toxicoinfection

·       Organism enters body, produces toxin in intestine after growth.

·       Examples:

ü  Clostridium perfringens

§  Transmitted through Meats and Gravies.

§  Spores survive cooking → germinate in warm food

§  Causes abdominal cramps and diarrhea within 8–24 hrs

ü  Bacillus cereus

§  Cause Diarrheal type food poisoning

NON-BACTERIAL FOOD-BORNE POISONING

A) Mycotoxins (Toxins from molds) - Produced by molds in grains, nuts, cereals, fruits, stored foods.

Mycotoxin	Mold	Food Sources	Effect
Aflatoxin	Aspergillus flavus	Groundnut, maize	Liver cancer, carcinogenic
Ochratoxin	Aspergillus & Penicillium	Cereals, coffee, fruits	Kidney damage
Patulin	Penicillium & Aspergillus	Spoiled apples, fruit juices	Gastrointestinal disorders
Ergot alkaloids	Claviceps purpurea	Rye, grains	Convulsions, hallucination
Fumonisins	Fusarium	Maize	Cancer risk

B) Viruses - Viruses cannot multiply in foods but use food as carriers.

Virus	Food Source	Symptoms
Hepatitis A	Shellfish, raw food, contaminated water	Jaundice, fever, nausea
Norovirus	Salads, shellfish, water	Vomiting, diarrhea (explosive outbreaks)
Rotavirus	Milk, water	Diarrhea in infants

C) Rickettsia

• Obligate intracellular parasites; rare in foods.
• Passed mainly through contaminated milk.
• Cause Q fever.

D) Food-Borne Parasites

Parasite	Food Source	Disease
Taenia saginata/T. solium	Beef / Pork	Tapeworm infection
Trichinella spiralis	Undercooked pork	Trichinosis
Giardia, Entamoeba	Water, salads	Diarrheal diseases

E) Seafood Toxins

Toxin	Source	Effect
Ciguatoxin	Reef fish	Neurological symptoms
Saxitoxin (Paralytic shellfish poison)	Shellfish → Dinoflagellates	Paralysis, respiratory failure
Tetrodotoxin	Puffer fish	Deadly neurotoxin

F) Chemical Poisoning

Chemicals accidentally or intentionally present in food:

• Pesticides
• Heavy metals (lead, mercury)
• Cleaning agents
• Naturally occurring plant toxins (solanine in potatoes, cyanogenic glycosides in cassava)