Causes:
The CDC (Centers for Disease Control) estimates that 97% of all cases of food poisoning result from improper food handling; 79% of cases result from food prepared in commercial or institutional establishments and 21% of cases result from food prepared at home.
The most common causes are (1) leaving prepared food at temperatures that allow bacterial growth, (2) inadequate cooking or reheating, (3) cross-contamination, and (4) infection in food handlers. Cross-contamination may occur when raw contaminated food comes in contact with other foods, especially cooked foods, through direct contact or indirect contact on food preparation surfaces.
Bacteria are responsible for approximately two thirds of the outbreaks of food poisoning with a known cause in the United States. As many as 1 in 10 Americans has diarrhea due to food-borne infection each year.