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Food poisoning

Last updated: August 30, 2021

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Food poisoning, or foodborne illness, occurs following the ingestion of food or water contaminated with bacteria, bacterial toxins, viruses, parasites, or chemical substances. According to the Centers for Disease Control and Prevention (CDC), an estimated 1 in every 6 people in the US is affected by a foodborne illness annually. Risk factors include the cross-contamination of food and improper handling and storage. Immunocompromised individuals are at an increased risk of infection. Common pathogens attributed to food poisoning include norovirus, Salmonella, Clostridium perfringens, Campylobacter jejuni, Staphylococcus aureus, and Escherichia coli. Incubation periods depend on the cause, and range from a few hours to days. The clinical presentation associated with food poisoning varies, but typical symptoms include diarrhea, nausea, vomiting, and abdominal cramping. Various laboratory tests (e.g., stool analysis, blood tests) help confirm the suspected diagnosis. Young children and the elderly are at greater risk for developing complications related to food poisoning and must be closely monitored. For most patients, supportive care, including fluid replenishment, is sufficient.

  • Pathogen: Bacillus cereus, a heat-stable, spore-forming gram-positive rod that produces two different enterotoxins
  • Transmission
    • The bacteria grows in heated food that cools down too slowly or is improperly refrigerated.
    • Reheated rice is a common source; of infection: Spores survive the cooking process and germinate when rice is kept warm, which results in enterotoxin formation. [1]
  • Incubation period and clinical findings
  • Treatment: supportive: , as antibiotics are not effective against toxins [3]

Poisoning from reheated rice can be serious (B. cereus).

Histamine fish poisoning (scombroid)

Reef fish poisoning (ciguatoxin)

  • Transmission: ingestion of reef fish containing Gambierdiscus toxicus
    • Barracuda
    • Moray eel
    • Snapper
    • Sea Bass
    • Amberjack
  • Mechanism of action: opening of Na+ channels → depolarization
  • Clinical features
  • Treatment: supportive

Puffer fish poisoning (tetrodotoxin)

Foodborne diseases may be classified according to the predominating symptoms. An overview is provided in this section. For details regarding the bacterial pathogens, see the article on bacterial gastroenteritis.

Predominantly vomiting

Pathophysiology: Vomiting is commonly due to delayed gastric emptying caused by changes to gastric motility.

Overview of pathogens predominantly causing vomiting
Pathogen Foods/transmission Incubation period Treatment

Staphylococcus aureus

  • Canned meats, mayonnaise/potato salad, custards
  • 1–8 hours
  • Supportive
Bacillus cereus
  • Reheated rice, food kept warm but not hot
  • Vomiting: 30 minutes to 6 hours
  • Diarrhea: 6–15 hours
  • Supportive

Noroviruses (e.g., Norwalk virus) [4]

  • Fecal-oral
  • 12–48 hours
  • Supportive


Symptom onset and resolution are quick in S. aureus and B. cereus poisoning: S. aureus and B. cereus are fast and fureus.

Predominantly diarrhea

Watery diarrhea

Overview of pathogens predominantly causing watery diarrhea
Pathogen Foods/transmission Incubation period Treatment
Staphylococcus aureus
  • Inadequately refrigerated food
  • 1–8 hours
  • Supportive

Clostridium perfringens [5][6]

(Heat-labile enterotoxins cause the symptoms.)

  • Germination of spores in heavily contaminated food that is left standing at < 60°C for too long → vegetative bacteria
  • The foods most likely to have been colonized include:
    • Reheated meat dishes
    • Undercooked meat and raw legumes
  • 6–24 hours
  • Supportive; usually resolves in 24 hours
  • Antibiotics are not recommended.

Enterotoxic Escherichia coli (ETEC) [7]

(Heat-labile toxin induces diarrhea; most common cause of traveler's diarrhea)

  • Recent travel (e.g., Asia, Africa, the Middle East, Mexico, Central, or South America)
  • Undercooked meat, endogenous
  • Fecal-oral
  • 9 h to 3 days
Listeria monocytogenes
  • Soft cheese, deli meats, unpasteurized milk, coleslaw, hot dogs,
  • 1–2 days
Vibrio cholerae
  • 0–2 days

Enteric viruses (adenovirus, norovirus, rotavirus)

  • Fecal-oral

Cryptosporidium [8]

  • Fecal-oral (oocysts are excreted in stool and contaminate drinking water)
  • 5–7 days
Cyclospora (Cryptosporidium cyclospora cayetanensis) [9][10]
  • Fecal-oral
  • 5–7 days
Intestinal tapeworms
  • Larvae in undercooked pork/beef, raw freshwater fish
  • 6–8 weeks
  • Asymptomatic for years

Invasive diarrhea

Overview of pathogens predominantly causing invasive diarrhea
Pathogen Foods/transmission Incubation period Treatment
Yersinia
  • 4–6 days
Salmonella typhi or paratyphi
  • Poultry/eggs, meat
  • Most commonly 7–14 days

Inflammatory diarrhea

Overview of pathogens predominantly causing inflammatory diarrhea
Pathogen Association Foods/transmission Incubation period Treatment
Salmonella (hundreds of strains, including S. enteritidis and S. typhimurium)
  • Poultry/eggs
  • Chicken products: eggs, raw chicken
  • 6–48 hours
Campylobacter jejuni
  • Poultry
  • Fecal-oral
  • Days
Shigella dysenteriae
  • Second most common association with hemolytic-uremic syndrome (HUS)
  • Fecal-oral
  • Days
Yersinia enterocolitica
  • More common in children and during the winter season
  • Contaminated milk, pork
  • Days
Vibrio (usually parahaemolyticus) [11][12]
  • Shellfish
  • Raw/undercooked seafood
  • 16–72 hours

Enterohemorrhagic Escherichia coli (EHEC) [7]

  • Undercooked meat
  • Untreated water; contaminated food, such as unpasteurized dairy products (milk, soft cheese) or apple cider
  • Fecal-oral
  • 3–4 days
  • Supportive
  • Antibiotics are contraindicated because they increase the risk of HUS.

Additional non-gastrointestinal symptoms

Pathogens Predominating symptoms Foods/Transmission Incubation period Treatment
Clostridium botulinum
  • Descending paralysis
  • Adults: respiratory support, antitoxin
  • Infants: respiratory support, hyperimmune human serum
  • Antibiotics may worsen or prolong disease
Histamine fish poisoning
  • Inadequately refrigerated fish
  • 5 minutes to 1 hour
Brucellosis (Brucella spp.) [13]
  • Unpasteurized dairy products
  • Contact with animals (e.g., hunter)
  • 2–4 weeks (range: 5 days to 5 months)
Hepatitis A (Hepatitis A virus) [14]
  • Jaundice, commonly following initial GI symptoms
  • Fecal-oral
  • 28 days (range 14–50 days)

Vibrio vulnificus [15][16]

  • Oysters, undercooked seafood
  • Contact with contaminated water or shellfish (wound infections)
  • 1–7 days
Salmonella typhi and paratyphi
  • Fecal-oral
  • Hours
Ciguatoxin
  • Reef fish containing Gambierdiscus toxicus
  • 6–24 hours
  • Supportive

Common sources of fecal-oral transmission in intestinal diseases are the 5 F's: fingers, feces, food, fluids, flies.

  • Food hygiene [17]
    • Wash hands and surfaces frequently.
    • Wash fruits and vegetables with safe drinking water.
    • Avoid cross-contamination by keeping raw meat products, eggs, and seafood separated from other kinds of food.
    • Use a food thermometer while cooking.
    • Maintain a refrigerator temperature < 4°C (40°F).
    • When traveling (especially to developing countries): Only consume fully cooked or dry (e.g., bread, crackers) foods, pasteurized dairy products, and fruits and vegetables you can peel or have properly washed yourself.
  • Water hygiene [18]
    • Do not consume untreated water or ice.
    • Options if water treatment is unknown:
      • Consume sealed bottled beverages.
      • Boil water for at least one minute before consuming.
      • Use an appropriate filter.

There is a simple rule to avoid foodborne illness while traveling: Boil it, cook it, peel it, or forget it.

  1. Norovirus (Norwalk Virus). https://www.foodsafety.gov/poisoning/causes/bacteriaviruses/norovirus/. Updated: April 10, 2017. Accessed: April 10, 2017.
  2. Clostridium perfringens. https://www.foodsafety.gov/poisoning/causes/bacteriaviruses/cperfringens/. Updated: April 10, 2017. Accessed: April 10, 2017.
  3. Food Safety: Clostridium perfringens. https://www.cdc.gov/foodsafety/diseases/clostridium-perfringens.html. Updated: January 10, 2017. Accessed: April 10, 2017.
  4. E.coli (Escherichia coli). https://www.cdc.gov/ecoli/general/. Updated: November 6, 2015. Accessed: April 10, 2017.
  5. Fayer R, Xiao L. Cryptosporidium and Cryptosporidiosis. Taylor & Francis Group ; 2007
  6. Treatment for Cyclosporiasis. https://www.cdc.gov/parasites/cyclosporiasis/health_professionals/tx.html. Updated: January 10, 2013. Accessed: April 10, 2017.
  7. Cryptosporidium: Treatment. https://www.cdc.gov/parasites/crypto/treatment.html. Updated: February 20, 2015. Accessed: April 10, 2017.
  8. Vibrio Infections. https://www.foodsafety.gov/poisoning/causes/bacteriaviruses/vibrio_infections/. Updated: April 10, 2017. Accessed: April 10, 2017.
  9. Vibrio Species Causing Vibriosis. https://www.cdc.gov/vibrio/index.html. Updated: October 24, 2016. Accessed: April 10, 2017.
  10. Brucellosis: Transmission. https://www.cdc.gov/brucellosis/transmission/index.html. Updated: November 12, 2012. Accessed: April 10, 2017.
  11. Fiore AE. Hepatitis A transmitted by food. Clin Infect Dis. 2004; 38 (5): p.705-715. doi: 10.1086/381671 . | Open in Read by QxMD
  12. Bross MH, Soch K, Morales R, Mitchell RB. Vibrio vulnificus Infection: Diagnosis and Treatment. Am Fam Physician. 2007; 76 (4): p.539-544.
  13. Daniels NA. Vibrio vulnificus oysters: pearls and perils. Clin Infect Dis. 2011; 52 (6): p.788-792. doi: 10.1093/cid/ciq251 . | Open in Read by QxMD
  14. Rosenthal KS, Tan MJ. Rapid Review Microbiology and Immunology, 3rd Edition. Elsevier ; 2010
  15. Staphylococcal Food Poisoning - CDC. https://www.cdc.gov/foodsafety/diseases/staphylococcal.html. Updated: August 9, 2018. Accessed: April 30, 2020.
  16. Food Safety: Information for the Public. https://www.cdc.gov/foodsafety/groups/consumers.html. Updated: September 1, 2016. Accessed: April 10, 2017.
  17. Cryptosporidium: Prevention & Control: General Public. https://www.cdc.gov/parasites/crypto/gen_info/prevention-general-public.html. Updated: October 7, 2015. Accessed: April 10, 2017.
  18. Gamarra RM. Food Poisoning. Food Poisoning. New York, NY: WebMD. http://emedicine.medscape.com/article/175569-overview. Updated: June 26, 2015. Accessed: April 10, 2017.