Hep A outbreak investigation in British Columbia aided by shopper loyalty cards

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My keychain is loaded with shopper loyalty cards, something that I was introduced to when I moved to North Carolina. Every few days when I take Sam grocery shopping (one of his favorite pastimes) I swipe the Food Lion, Harris Teeter or Lowe’s Foods barcode to get our deals. images

We also get email alerts if something we purchased has a safety issue – a nice secondary benefit – but like Bill Hallman says, awareness is only the first step in recalls.

The U.S. Centers for Disease Control and Prevention (CDC) have been touting the use of shopper loyalty cards as epidemiological tools for years. Lots of data is collected by retailers with every swipe: date, product, lot, location. CDC reported that the cards aided in an investigation into a 2009 outbreak of Salmonella montevideo linked to pepper (which was used as an ingredient in multiple foods).

The late Bill Keene told NBC News in 2013 “We rely on people’s memories, which are quite fallible, and on our interviews, which are quite fallible. Shopper club cards are a good source of finding out what people ate.”

The good folks at the other CDC, the British Columbia Centers for Disease Control (that’s in Canada) published a report in Eurosurvellance this week about a hepatitis A outbreak investigation  that was solved using loyalty cards.

In 2012, an investigation was launched following the identification of three non-travel-related hepatitis A cases within one week in one of BC’s five geographically based health authorities, compared with 10 hepatitis A cases in the affected HA in the previous year, six of which were related to travel to endemic countries

 Authorisation was obtained from cases who shopped at major supermarket chains for those chains to release detailed shopping histories via the cases’ store loyalty cards. Shopping histories going back three months were analysed to include products with an extended refrigerated or frozen storage life.

Food purchase histories obtained from the initial six possible cases showed that the majority (n=5) had shopped for groceries at a major chain of affiliated supermarkets. Analysis of loyalty card use indicated that three of the six cases had purchased the same frozen fruit blend at that retail chain. Consumption or not of the product was confirmed by interview for all six cases.
 
The outbreak team asked the chain to provide further details on production and distribution of this product in the third week of March 2012.  It was a blend of raw frozen fruit (blueberries, strawberries, dark cherries and pomegranate seeds) in a 600 g package produced under a private house label for the supermarket chain and distributed to their stores in BC and the neighbouring province of Alberta. Multiple lot codes had been purchased by the cases. The chain described the product as relatively uncommon, with sales of approximately 56,000 units of the product to 31,000 households throughout the two provinces during the four months before the query.
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About Ben Chapman

Dr. Ben Chapman is a professor and food safety extension specialist at North Carolina State University. As a teenager, a Saturday afternoon viewing of the classic cable movie, Outbreak, sparked his interest in pathogens and public health. With the goal of less foodborne illness, his group designs, implements, and evaluates food safety strategies, messages, and media from farm-to-fork. Through reality-based research, Chapman investigates behaviors and creates interventions aimed at amateur and professional food handlers, managers, and organizational decision-makers; the gate keepers of safe food. Ben co-hosts a biweekly podcast called Food Safety Talk and tries to further engage folks online through Instagram, Twitter, Facebook, YouTube and, maybe not surprisingly, Pinterest. Follow on Twitter @benjaminchapman.