CausesBy Mayo Clinic staff
Contamination of food can happen at any point during its production: growing, harvesting, processing, storing, shipping or preparing. Cross-contamination — the transfer of harmful organisms from one surface to another — is often the cause. This is especially troublesome for raw, ready-to-eat foods, such as salads or other produce. Because these foods aren't cooked, harmful organisms aren't destroyed before eating and can cause food poisoning.
Many bacterial, viral or parasitic agents cause food poisoning. The following table shows some of the possible contaminants, when you might start to feel symptoms and common ways the organism is spread.
|Contaminant||Onset of symptoms||Foods affected and means of transmission|
|Campylobacter||2 to 5 days||Meat and poultry. Contamination occurs during processing if animal feces contact meat surfaces. Other sources include unpasteurized milk and contaminated water.|
|Clostridium botulinum||12 to 72 hours||Home-canned foods with low acidity, improperly canned commercial foods, smoked or salted fish, potatoes baked in aluminum foil and other foods kept at warm temperatures for too long.|
|Clostridium perfringens||8 to 16 hours||Meats, stews and gravies. Commonly spread when serving dishes don't keep food hot enough or food is chilled too slowly.|
|Escherichia coli (E. coli) O157:H7||1 to 8 days||Beef contaminated with feces during slaughter. Spread mainly by undercooked ground beef. Other sources include unpasteurized milk and apple cider, alfalfa sprouts and contaminated water.|
|Giardia lamblia||1 to 2 weeks||Raw, ready-to-eat produce and contaminated water. Can be spread by an infected food handler.|
|Hepatitis A||28 days||Raw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.|
|Listeria||9 to 48 hours||Hot dogs, luncheon meats, unpasteurized milk and cheeses, and unwashed raw produce. Can be spread through contaminated soil and water.|
|Noroviruses (Norwalk-like viruses)||12 to 48 hours||Raw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.|
|Rotavirus||1 to 3 days||Raw, ready-to-eat produce. Can be spread by an infected food handler.|
|Salmonella||1 to 3 days||Raw or contaminated meat, poultry, milk or egg yolks. Survives inadequate cooking. Can be spread by knives, cutting surfaces or an infected food handler.|
|Shigella||24 to 48 hours||Seafood and raw, ready-to-eat produce. Can be spread by an infected food handler.|
|Staphylococcus aureus||1 to 6 hours||Meats and prepared salads, cream sauces and cream-filled pastries. Can be spread by hand contact, coughing and sneezing.|
|Vibrio vulnificus||1 to 7 days||Raw oysters and raw or undercooked mussels, clams and whole scallops. Can be spread through contaminated seawater.|
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- Fight BAC. Partnership for Food Safety Education. http://www.fightbac.org/storage/documents/flyers/fightbac_color_brochure.pdf. Accessed April 20, 2011.
- Minimum cooking temperatures. FoodSafety.gov. http://www.foodsafety.gov/keep/charts/mintemp.html. Accessed April 20, 2011.