NZ fails to identify source of gastroenteritis outbreak

An outbreak of Yersinia pseudotuberculosis has been reported in New Zealand. The Ministry of Health (MoH) and Ministry for Primary Industries (MPI) have been working to discover the cause of the outbreak but thus far have been unable to pinpoint the source.

Yersinia pseudotuberculosis causes stomach cramps and can present symptoms similar to appendicitis. It has a three to 21-day incubation period. While cases are reported each year, New Zealand had an increase in cases in September 2014.

The government bodies initially narrowed the search down to a range of fresh produce, with those suffering from gastroenteritis most frequently recalling having eaten lettuce, carrots, tomatoes, apples, cold ready-to-eat meats and dairy products.

Incomplete and preliminary information was released to the media before the cause of the outbreak could be confirmed, further fuelling 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 [Institute of Environment and Science and Research] today,” said MPI Deputy Director General Regulation and Assurance.

While the case-control studies identify a range of foods that need to be further investigated, 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 pre-mixed salads, covered by many brands,” said Gallacher.

“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.

“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.”

For more information about the outbreak, and to access the ESR Reports, click here.