A profile of the study “Dirty Money: An Investigation into the Hygiene Status of Some of the World’s Currencies as Obtained from Food Outlets.” The level of fecal bacteria contamination on banknotes is compared between Australia, Burkina Faso (Africa), China, Ireland, the Netherlands, New Zealand, Nigeria, Mexico, the United Kingdom, and the United States.
Since so few restaurant and deli workers wash their hands (see Restaurant Worker Hand Washing, and Hand Washing Compliance of Retail Deli Workers), it should come as no surprise that anything they handle can become contaminated. Most meat is contaminated with fecal bacteria (see Fecal Bacteria Survey)—in fact, so much so that children can pick up infections by just touching the outside of meat packaging. See Meat-Borne Infection Risk from Shopping Carts, and check out my other videos on food poisoning.
For more context, check out my associated blog post: Probiotics and Diarrhea.