The biggest cause of foodborne illness is

The biggest cause of foodborne illnesses is the handling and preparation of these foods.

Explanation:

Foodborne diseases or STDs are caused by eating contaminated food or beverages, in amounts that affect consumer health. Most are infections caused by bacteria and their toxins, viruses and parasites. These microorganisms are usually transmitted by handling and preparing food inappropriately and without hygiene.

Prevention is done as follows: wash your hands regularly; disinfect all surfaces, utensils and equipment used in food preparation; choose fresh foods that look good, and before consumption they should be washed; avoid eating raw foods, with the exception of fruits and vegetables that can be peeled, whose skins are healthy; buy safe food by checking expiration date, packaging and physical conditions (appearance, consistency, odor); buy meat inspected by the federal inspection service; do not buy food without a label that identifies the producer; fish and shellfish of certain species, and in some countries in particular, may be contaminated with toxins that remain active, despite good cooking; consume pasteurized and sterilized milk (UHT); avoid the consumption of raw, undercooked foods (salads, meats, among others); avoid food sold by street vendors, as it is not known if there was hygiene in the preparation of these products or if they are being stored properly; keep food out of the reach of insects, rodents and other animals.

when you rub, you also apply pressure, that pressure can urge the poop to come out. i think that when your rubbing, you also might be slightly breaking it up and that can further fill the stomach.