Disease Detectives: Using supermarket loyalty cards to trace an E Coli outbreak


In November 2017, supermarket loyalty cards have been used to trace the supply of a giant E Coli outbreak affecting primarily males in England. Dr Lisa Byrne leads Public Health England’s surveillance of two key micro organism that lead to meals poisoning – E Coli and Listeria. Dr Kathie Grant heads the PHE Gastrointestinal Bacteria Reference Laboratory. The two work collectively as half of a bigger group devoted to decreasing meals borne sickness and beneath inform us how they put the items of this puzzle collectively to discover the supply.

If you’ve ever had meals poisoning you’ll know that feeling of mentally going by way of every part you ate not too long ago, attempting to pinpoint what it was that may have made you ailing. It’s our job to try this at a nationwide scale.  We deliver collectively a number of completely different items of  data from the group and the lab to attempt to discover  the supply of a meals poisoning outbreak after which, working alongside different authorities businesses,  be certain that extra folks don’t get sick.

Telling one E coli from one other

We examine and monitor many alternative abdomen bugs – a few of which you’ll by no means have heard of! While abdomen bugs are part of life, PHE works with organisations such because the Food Standards Agency and the Animal and Plant Health Agency to try to forestall them.

Every so usually we see a spike within the variety of instances.  When this occurs it will be important that we discover the hyperlink between the instances and the reason for their sickness.  To do that we’d like to determine the precise pressure of a bug to perceive if folks have gotten ailing from the very same supply.

Whole Genome Sequencing (WGS) ‒ a comparatively new course of for displaying us the make-up of a bacterium or virus’s genes ‒ has modified the best way we are able to discover the reason for an outbreak and cease extra folks getting ailing. You can study extra concerning the course of and the way it works in our explainer blog.

Before WGS it may take weeks to determine micro organism and generally the micro organism could possibly be missed. This slowed down any investigations  as we couldn’t make certain that all of the case histories we have been taking could possibly be linked to an outbreak – there was a whole lot of ‘noise’ and false traces of enquiry. With WGS, we are able to quickly and precisely determine if micro organism of instances are the identical pressure and rule out folks from our investigation who simply occurred to be ailing on the similar time, however with a special sickness.

It has additionally expanded what the phrase ‘outbreak’ means as we are able to hyperlink instances throughout a number of years and completely different international locations, which means we are able to extra precisely piece collectively an image of how one thing within the meals provide chain impacts human health.

Jigsaw puzzles and loyalty cards

Scientists working within the Gastrointestinal Bacteria reference laboratory at Public Health England. The group are processing samples from individuals who have reported gastrointestinal signs, to perceive the precise reason behind their sickness.

Identifying the supply of an outbreak is quite a bit like placing collectively a jigsaw puzzle, combining a number of items of proof to get the total image. Sometimes, a typical supply is clear, reminiscent of when a gaggle of individuals get ailing after eating the identical meal, on the similar restaurant, on the identical day. But different occasions, we’d like to use an arsenal of investigative instruments, as was the case in a current E coli outbreak.

In November 2017 our surveillance system alerted us to 12 instances of E coli O157 – (a selected type of E coli), over a six week window. E coli O157 is a comparatively uncommon reason behind meals poisoning, with solely about 700 instances a 12 months, however it could possibly trigger a really extreme sickness. Because of this, any case of E coli O157 recognized by medical doctors and laboratories have to be reported to Public Health England.  We monitor the variety of instances with our surveillance techniques to discover any patterns.

Very shortly our reference laboratory used WGS which confirmed that the instances had the similar genetic “fingerprint” and the work started to trace the supply of an infection. The majority of people that grew to become ailing have been males, which was uncommon as E coli outbreaks are sometimes linked to salad objects ‒ historically extra doubtless to be eaten by girls.

It took a couple of rounds of interviews – carried out by colleagues in native authorities – to zero in on the potential supply of meals poisoning, and an image started to emerge that implicated burgers from a selected retailer.

We requested the supermarket to analyse the loyalty card information of those that had change into ailing, to assist determine the actual burger product the instances had eaten.  As you possibly can think about, there have been many various kinds of burgers provided by the supermarket and it’s usually troublesome for folks to bear in mind precisely what they ate.

Working with the Food Standards Agency we have been ready to determine that each one the instances had purchased a selected model of burger, main to a product recall to guarantee others didn’t get sick. The recall concerned eradicating all of the suspected batches of burgers from the supermarket cabinets. The supermarket additionally contacted individuals who had purchased the burgers, advising them not to eat them and return them for a refund.

Sometimes, as on this case, we are able to quickly discover what’s making folks ailing and shortly take away it from sale. It’s an thrilling position and we get an actual sense of satisfaction out of utilizing our abilities to assist folks on this manner. Other occasions it may be extra irritating – some outbreaks stay unsolved and it’s an actual fear that individuals will get sick as a result of we are able to’t eradicate a risk from meals distribution.

Changing meals habits

The position actually retains us on our toes. Our surveillance techniques imply that we have now a great sense of patterns of sickness throughout the 12 months and the way we are able to intervene to cease folks getting unwell – however adjustments to meals habits can catch us unexpectedly. For occasion, uncooked milk has change into extra in style not too long ago, bringing with it all of the illness dangers you’ll anticipate from a product that has come straight from a cow with none remedy to kill off micro organism!

In one other case, eight folks within the UK have been affected whereas on vacation in Germany that was associated to seeds.  The seeds have been decoratively used as a garnish on salads and have been troublesome for instances to bear in mind eating. Nearly 1,000 folks in Germany acquired ailing in that outbreak and one of many approaches by authorities was to use vacationer pictures of meals to try to determine the widespread merchandise in meals that could possibly be making folks sick.

Solving meals borne sickness outbreaks is usually a actual problem, however through the use of a wide range of the completely different instruments obtainable to us we are able to shortly intervene to cease folks getting ailing.

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