The shopper loyalty cards that your grocery store provides can have a higher purpose than giving you discounts, profiling your shopping habits, and racking up points for rewards programs. Loyalty card data can also help track down the source of foodborne pathogens, retaining records of specific brands and items that customers probably won’t remember. Trying to find the source of a mysterious salmonella outbreak, the CDC mined grocery loyalty card data to narrow the source down to specific brands of Italian cured meat.
Through interviews and questionnaires, investigators suspected some kind of Italian meat was the culprit, but people couldn’t remember what brand they bought, [CDC epidemiologist Casey Barton] Behravesh said.
So the CDC asked supermarkets for certain buying information on seven victims in Washington state, focusing on suspect products rather than everything the customers had bought, Behravesh said. “We didn’t care about the brand of toilet paper people were buying,” she said.
Of those seven people, five had bought Italian meats made by the Rhode Island company, Daniele International Inc., Behravesh said.
Further investigation — including the use of data from other victims’ shopper cards — pointed to salami made by Daniele and, more specifically, the imported pepper it was coated in. That came from two spice suppliers in New York and New Jersey. All three companies have since recalled some products.
In this case, only people who had salmonella and gave permission for the CDC to look at their shopping history. Some grocery chains take this concept and reverse it, contacting customers who have purchased potentially dangerous items.