Report authors Dr Jonathan Jarman, Dr Chris Niebuhr, Prof Nick Wilson (of the University of Otago) and Prof Jackie Benschop published the paper "Rodents running riot in supermarkets" late last month.
The paper was published on the Public Health Communication Centre website, in response to coverage of recent rodent outbreaks, particularly that in Dunedin South Woolworths (formerly Countdown Dunedin South) earlier this year.
The business was closed for 18 days in February, after numerous sightings and captures of rodents in-store.
"Supermarkets are very attractive for rodents because of the large amount of food and places to hide," the report said.
"For every rodent seen during the day it is estimated that there are 20 to 50 individuals that are unseen.
"It is likely that climate change with warmer weather and more extreme weather events will increase rodent populations and increase the adverse impacts on humans."
The authors said it was usually difficult to "pinpoint rodents as the cause of a food-borne illness" and "there is a lack of evidence on the scale of this source of infection in New Zealand".
"While finding evidence of rodent activity in human food can be very upsetting, it is likely that it causes only a small part of the total enteric disease burden."
Despite this, it was "clear that all businesses involved in the food supply chain require pest management strategies combined with stringent food safety standards and a zero tolerance to rodent sightings".
There were also "significant health risks from eating ready-to-eat food contaminated by rodents".
Lead author Dr Jarman, a former medical officer of health, told the Otago Daily Times the research paper proved timely.
"I think most of New Zealand was captivated by the photos and videos of rodents running riot around supermarkets at the start of this year.
"We tend to be a bit relaxed about cute rodents but there are some real health risks. I thought that it would be timely to do an article so approached my co-authors to see if they were interested in helping.
Since writing the article, he had heard many tales about rodents.
"The best so far are a brown rat in the toilet bowl, a black rat nicknamed ‘Hoover’ because he or she kept stealing edibles from under the Christmas tree, and a rat in a tramping hut who refused to take "not for you" as an answer. These stories all point to the fact that rodents in Aotearoa New Zealand are very common."
Dr Jarman said it was highly likely that most supermarkets were fully aware of rodents.
"A supermarket is a rodent utopia — unlimited yummy foods and lots of places to hide.
"There have been some successes but we feel it is extremely unlikely that we will be able to totally get rid of rodents using our current methods for rodent control.
"Rodents are smart and highly invasive. Elimination for the entire North or South Island would need help from some extra technology, perhaps at a genetic level."
