Yersinia pseudotuberculosis – update 16 October 2014

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MPI Deputy Director General Regulation and Assurance Scott Gallacher said MPI is continuing to seek to identify the origins of the outbreak, drawing upon the best available expertise and information, both domestically and internationally.

Food safety is the Ministry for Primary Industries highest priority in relation to the outbreak of illness caused by Yersinia pseudotuberculosis.

“The health data is telling us we are dealing with a contamination event that happened in August. This was identified as an outbreak of illness on 23 September.

“According to the latest health data, there have been no further confirmed cases since the first week of October.”

MPI is today releasing the case-control studies, commissioned by the Ministry of Health, and produced by the Institute of Environment and Science and Research to identify foods for further investigation in locating the source of this outbreak (

Mr Gallacher said incomplete and preliminary information was released to the media last week, which has fuelled speculation.

“While the investigation has not yet identified the source, it is important to stop the speculation as to what foods are being investigated, which is why we are releasing the case-control studies from ESR today,” Mr Gallacher said.

“The case-control studies were produced by scientists for specialists conducting a food safety investigation.  A summary of the key findings is also being released with the working documents.”

Mr Gallacher said the case-control studies from ESR identify a range of foods that need further investigation to establish if they are the source of this illness. They do not provide a definitive list of affected foods.

“In the case of lettuce, which is identified as a food to investigate, there are numerous varieties of whole lettuce, leaves, leaves of mixed varieties, and premixed salads, covered by many brands.

“Lettuce is a very commonly consumed food, which was consumed throughout this outbreak with the vast majority of consumers not becoming ill. Most of the patients surveyed remembered eating some kind of lettuce, with 8 out of 96 remembering one brand, but the vast majority of those surveyed could not specify the type or brand of product.

“We are getting a lot of information, building a picture and investigating many avenues.

“It is not a simple situation where we can recall a single product. It is not definitively linked to any one producer, distributor, wholesaler or retailer. The ESR case-control studies have provided useful pointers for continuing investigation.

“MPI has been checking with major food suppliers to ensure the food handling practices are meeting the required standard.

MPI continues to advise normal food safety practice. If it looks off or smells off, throw it out. Otherwise keep fresh food chilled and wash fruit and vegetables before eating.

This remains the best preventative information available.

See your doctor if you think you might have symptoms.

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