Food Poisoning

Food poisoning occurs when you consume food or beverages contaminated with harmful pathogens or their toxins. These contaminants can enter food at any point during production, processing, or cooking. The severity and duration of symptoms depend on the type of contaminant, the amount consumed, and individual factors such as age and overall health.

Contamination can occur through various routes: infected food handlers who don't wash their hands properly, cross-contamination between raw and cooked foods, improper storage temperatures, inadequate cooking, or contaminated water used in food preparation. Some organisms produce toxins in food before it's consumed, while others cause infection after being ingested.

While the term "stomach flu" is often used interchangeably with food poisoning, they are different conditions. Stomach flu (viral gastroenteritis) is caused by viruses spread from person to person, while food poisoning results from consuming contaminated food or drink. The symptoms can be similar, making it sometimes difficult to distinguish between them without knowing the source of infection.

Bacterial Causes

Salmonella

• Most common bacterial cause
• Found in: Raw eggs, poultry, meat, unpasteurized dairy
• Onset: 6-72 hours
• Duration: 4-7 days
• Can cause typhoid fever (S. typhi)

E. coli (Escherichia coli)

• Several strains, some produce Shiga toxin
• Found in: Undercooked ground beef, contaminated produce, unpasteurized milk
• Onset: 1-8 days
• Duration: 5-10 days
• Can cause hemolytic uremic syndrome (HUS)

Campylobacter

• Leading cause of bacterial diarrhea
• Found in: Raw poultry, unpasteurized milk, contaminated water
• Onset: 2-5 days
• Duration: 2-10 days
• Can trigger Guillain-Barré syndrome

Listeria monocytogenes

• Serious for pregnant women and immunocompromised
• Found in: Deli meats, soft cheeses, raw sprouts
• Onset: 1-4 weeks
• Can cause miscarriage, stillbirth

Staphylococcus aureus

• Produces toxins in food
• Found in: Foods left at room temperature, mayonnaise-based dishes
• Onset: 30 minutes to 6 hours
• Duration: 24-48 hours
• Rapid onset of severe symptoms

Clostridium perfringens

• Common in foods served in large quantities
• Found in: Meat dishes kept warm for extended periods
• Onset: 6-24 hours
• Duration: 24 hours

Viral Causes

Norovirus

• Most common viral cause
• Highly contagious
• Found in: Contaminated water, shellfish, salads
• Onset: 12-48 hours
• Duration: 1-3 days
• Causes projectile vomiting

Hepatitis A

• Affects liver
• Found in: Contaminated water, shellfish, produce
• Onset: 15-50 days
• Can cause jaundice
• Vaccine preventable

Rotavirus

• Common in children
• Onset: 1-3 days
• Duration: 3-8 days
• Vaccine available

Parasitic Causes

Giardia

• Found in: Contaminated water, unwashed produce
• Onset: 1-3 weeks
• Causes chronic diarrhea
• Common in hikers (beaver fever)

Cryptosporidium

• Resistant to chlorine
• Found in: Swimming pools, contaminated water
• Onset: 2-10 days
• Severe in immunocompromised

Cyclospora

• Found in: Imported produce, herbs
• Onset: 1 week
• Causes prolonged diarrhea
• Requires specific treatment

Toxins and Chemicals

Botulism (Clostridium botulinum)

• Rare but life-threatening
• Found in: Improperly canned foods, honey (infants)
• Onset: 18-36 hours
• Causes paralysis
• Medical emergency

Scombroid Poisoning

• From histamine in spoiled fish
• Found in: Tuna, mackerel, mahi-mahi
• Onset: Minutes to hours
• Causes flushing, rash

Mushroom Poisoning

• From toxic wild mushrooms
• Onset: Variable (minutes to days)
• Can cause liver/kidney failure
• Some types fatal

Pathogen-Specific Symptoms

Salmonella

• Diarrhea (sometimes bloody)
• Fever
• Abdominal cramps
• Headache
• May develop reactive arthritis

E. coli (STEC)

• Severe stomach cramps
• Bloody diarrhea
• Vomiting
• Low-grade fever or no fever
• HUS symptoms: decreased urination, fatigue, losing pink color in cheeks

Listeria

• Fever
• Muscle aches
• Nausea and diarrhea
• If spreads to nervous system: headache, stiff neck, confusion, loss of balance
• In pregnancy: mild flu-like symptoms but serious fetal complications

Botulism

• Double vision
• Blurred vision
• Drooping eyelids
• Slurred speech
• Difficulty swallowing
• Muscle weakness
• Paralysis (descending)

Timeline of Symptoms

• 30 minutes - 6 hours: Staph aureus, chemical contamination
• 6-24 hours: Clostridium perfringens
• 12-48 hours: Norovirus, Salmonella
• 1-8 days: E. coli
• Days to weeks: Listeria, parasites

High-Risk Groups

Age-Related

• Infants and young children: Immature immune systems
• Elderly (65+): Weakened immune response
• More severe symptoms
• Higher complication rates
• Longer recovery times

Pregnant Women

• Changed immune system
• Risk to fetus
• Particularly vulnerable to Listeria
• Should avoid high-risk foods

Immunocompromised Individuals

• HIV/AIDS patients
• Cancer patients on chemotherapy
• Organ transplant recipients
• People on immunosuppressant medications
• Diabetes patients

Environmental Risk Factors

• Season: Higher rates in summer
• Travel: Different food safety standards
• Group settings: Buffets, potlucks, catered events
• Restaurant dining: Especially buffets
• Street food: Variable hygiene standards

High-Risk Foods

Raw or Undercooked

• Raw eggs (cookie dough, homemade mayo)
• Raw meat and poultry
• Raw seafood (sushi, oysters)
• Unpasteurized milk and cheese

Ready-to-Eat Foods

• Deli meats and hot dogs
• Pre-made salads
• Soft cheeses
• Pâtés and meat spreads

Produce

• Raw sprouts
• Pre-cut melons
• Unwashed lettuce and herbs
• Berries

Behavioral Risk Factors

• Poor hand hygiene
• Inadequate cooking temperatures
• Cross-contamination practices
• Improper food storage
• Eating food past expiration
• Thawing food at room temperature

Clinical Evaluation

• Symptom history and timeline
• Recent food consumption (48-72 hours)
• Travel history
• Sick contacts
• Medication use
• Physical examination

Laboratory Tests

Stool Tests

• Stool culture: Identifies bacteria
• Ova and parasite exam: For parasites
• PCR tests: Rapid pathogen identification
• Toxin assays: For C. difficile, others
• May take 1-3 days for results

Blood Tests

• Complete blood count
• Electrolyte levels
• Kidney function
• Liver function (if indicated)
• Blood cultures (if sepsis suspected)

When Testing Is Recommended

• Severe or persistent symptoms
• Blood in stool
• High fever
• Signs of dehydration
• Symptoms lasting >3 days
• Outbreak investigation
• High-risk patients

Differential Diagnosis

Conditions with similar symptoms:

• Viral gastroenteritis
• Inflammatory bowel disease
• Irritable bowel syndrome
• Appendicitis
• Medication side effects
• Other infections

Most cases of food poisoning resolve on their own within a few days. Treatment focuses on preventing dehydration and managing symptoms:

Fluid Replacement

Oral Rehydration

• Small, frequent sips of fluids
• Oral rehydration solutions (ORS)
• Clear broths
• Electrolyte drinks
• Avoid caffeine and alcohol
• Ice chips or popsicles if nauseated

IV Fluids

• For severe dehydration
• Persistent vomiting
• Unable to keep fluids down
• Signs of shock

Dietary Management

During Acute Phase

• Clear liquids initially
• BRAT diet (Bananas, Rice, Applesauce, Toast)
• Small, frequent meals
• Avoid dairy, fatty foods, spicy foods
• No alcohol or caffeine

Recovery Diet

• Gradually return to normal diet
• Start with bland foods
• Reintroduce dairy slowly
• Continue avoiding irritants
• Focus on easy-to-digest foods

Medications

Generally NOT Recommended

• Anti-diarrheal drugs: Can prolong infection
• Antibiotics: Usually not needed, can worsen some infections
• May interfere with toxin elimination
• Can increase risk of complications

When Medications Are Used

• Antibiotics for:
  • Severe salmonella in high-risk patients
  • Shigella infections
  • Certain parasites
  • C. difficile (specific antibiotics)
• Anti-emetics: For severe nausea (prescription)
• Probiotics: May shorten duration

Home Care

• Rest - allow body to fight infection
• Stay home to prevent spread
• Monitor temperature
• Track fluid intake and output
• Watch for dehydration signs
• Gradual return to activities

When to Seek Medical Care

• Signs of severe dehydration
• Blood in vomit or stool
• High fever (>101.5°F/38.6°C)
• Severe abdominal pain
• Symptoms lasting >3 days
• Neurological symptoms
• If in high-risk group

Safe Food Handling

Clean

• Wash hands for 20 seconds with soap
• Wash before and after handling food
• Clean surfaces and utensils between uses
• Rinse fruits and vegetables
• Don't wash meat or poultry

Separate

• Use separate cutting boards for raw meat and produce
• Keep raw meat away from other foods
• Use separate plates for raw and cooked foods
• Store raw meat on bottom shelf of fridge

Cook

• Use food thermometer
• Safe minimum temperatures:
  • Ground meat: 160°F (71°C)
  • Poultry: 165°F (74°C)
  • Beef, pork, lamb: 145°F (63°C)
  • Fish: 145°F (63°C)
  • Eggs: 160°F (71°C)
• Reheat leftovers to 165°F (74°C)

Chill

• Refrigerate within 2 hours (1 hour if >90°F outside)
• Keep refrigerator at 40°F (4°C) or below
• Keep freezer at 0°F (-18°C)
• Thaw in refrigerator, not on counter
• Don't overfill refrigerator

High-Risk Food Guidelines

• Avoid raw eggs and undercooked eggs
• Don't eat raw cookie dough
• Avoid unpasteurized products
• Be cautious with seafood
• Heat deli meats until steaming
• Avoid raw sprouts

When Dining Out

• Check restaurant inspection scores
• Ensure food is served hot
• Send back undercooked food
• Refrigerate leftovers promptly
• Be cautious with buffets
• Avoid raw/undercooked items if high-risk

Travel Precautions

• Drink only bottled or boiled water
• Avoid ice cubes
• Eat only fully cooked hot foods
• Avoid street vendor food
• Peel fruits yourself
• Avoid raw vegetables
• Consider hepatitis A vaccine

Dehydration

• Most common complication
• Can be severe in young children and elderly
• Signs: dry mouth, decreased urination, dizziness
• May require hospitalization
• Can lead to kidney problems

Pathogen-Specific Complications

Hemolytic Uremic Syndrome (HUS)

• From E. coli O157:H7
• Destroys red blood cells
• Causes kidney failure
• Most common in children
• Requires dialysis in severe cases

Guillain-Barré Syndrome

• Rare complication of Campylobacter
• Immune system attacks nerves
• Causes muscle weakness and paralysis
• Usually reversible with treatment

Reactive Arthritis

• Can follow Salmonella, Shigella, Campylobacter
• Joint pain and swelling
• Usually develops 1-4 weeks after infection
• May last months to years

Chronic Conditions

• Post-infectious IBS
• Lactose intolerance
• Chronic fatigue
• Malabsorption issues

Serious Complications

• Sepsis: Blood infection
• Meningitis: From Listeria
• Miscarriage: From Listeria in pregnancy
• Death: Rare but possible, especially in vulnerable populations

Recovery Timeline

• Most cases: 1-3 days
• Viral causes: 1-3 days
• Bacterial causes: 3-7 days
• Parasitic causes: Weeks to months
• Full recovery: 1-2 weeks for energy levels

Factors Affecting Recovery

• Type of pathogen
• Amount of contamination
• Individual immune status
• Age and overall health
• Promptness of treatment
• Hydration maintenance

Return to Normal Activities

• Wait 48 hours after symptoms stop
• Food handlers may need clearance
• Healthcare workers follow specific protocols
• Gradual return to normal diet
• Continue good hygiene practices

Long-term Effects

Most people recover completely, but some may experience:

• Temporary lactose intolerance
• Altered gut microbiome
• Increased sensitivity to certain foods
• Post-infectious IBS in some cases
• Rarely, chronic complications