Already high rates of a serious and incurable disease that targets young people are continuing to climb in Canterbury.
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Research a decade ago revealed the district had a high incidence of Crohn's Disease and Ulcerative Colitis.
Now, new findings show rates of the disease have climbed even higher and are now among the highest reported anywhere in the world.
Crohn's and Ulcerative Colitis are life-long, chronic diseases of the auto-immune system due to inflammation in the intestine.
A study in 2004 showed 16.5 people per 100,000 in Canterbury had Crohn's Disease.
Christchurch gastroenterologist Richard Gearry, who was an author of the original study, said updated findings using an identical methodology in 2014 revealed a substantial increase.
"What we found was that overall for Inflammatory Bowel Disease (IBD), so Crohn's Disease and Ulcerative Colitis combined, we had 39 per 100,000, which was a very high rate," he said.
"But that the rate of Crohn's Disease in particular had increased from 16.5 per 100,000 up to 26 per 100,000 in a 10-year period."
He said that apart from Nelson, similar studies had not been done more widely but rates would probably be similar elsewhere.
"We're not too different to other parts of the country in Canterbury.
"Maybe we don't have the same number of people with Māori or Pacific Island ethnicity as other parts of the country, but certainly I think the rates are probably similar.
"And we'll be seeing similar rises in other parts of the country as well."
In the 2014 study, 205 patients were diagnosed with IBD in Canterbury - mostly Crohn's - 90 percent of them by colonoscopy.
Ages of people affected ranged from 5 to 88, with the incidence rate peaking between 20 and 24.
The study said the reasons for the increase over the period remained unclear and it was not designed to explain that.
But it said there would be costs associated with the rise, with another local study estimating an annual cost of almost $30 million and $36.7m for paediatric and perianal disease respectively.
"Further increases in the incidence rates of IBD indicate growing health-system demands in the coming years."
The study pointed out the disease was primarily diagnosed in young people but was not universally fatal.
"As the incidence of IBD increases, the burden of morbidity on patients, their families, the healthcare system and the community will also continue to increase."
Another co-author of the latest study, paediatrician Andrew Day of the University of Otago in Christchurch, said the impact was huge.
"We've seen almost twice as many people being diagnosed over that 10 years and people with Crohn's Disease have a lifetime of inflammation.
"The disease at this point is incurable, so that means twice as many people throughout the rest of their life having an impact upon the health system."
Professor Gearry said patients in New Zealand now had more equitable access to effective new biological drugs like infliximab and adalimumab, which were useful for people with more severe disease.
"There are now new drugs available-- in particular one called vedolizumab - [and] another called ustekinemab.
"They are now available in Australia, certainly vedolizumab, and we would like access to those drugs in New Zealand because certainly while we have drugs that work for some people there's still a significant unmet need."
He said the drugs suppressed the immune system, but one worked specifically on the gut, which would mean some side-effects of other drugs could be avoided.
'Missing link'
Prof Gearry said increases in IBD were also being seen in some other parts of the world, including North America, Europe and Australasia.
He said it was hard to pick exactly what was behind the increase, but it was seen with urbanisation and westernisation.
"Increasingly we think that the gut microbiome, or the billions of bacteria, or trillions of bacteria that live within our gut, are the key to this," he said.
"They may be the missing link between whatever is going on in our environment and our risk of getting these diseases."
Crohn's and Colitis New Zealand chairman Brian Poole said the impact of a diagnosis on children and teens could be considerable.
"They're frightened. It's the pain, it's the stress. They can't go to school, the nausea, vomitting. They're also being emptied frequently, they're losing weight, they're bleeding."
He said the group had recognised the importance of meeting the emotional needs of the children, which doctors had also been pushing for.
"So we've been holding holiday camps for the last two or three years, together with their parents, and we bring children from all around New Zealand at no cost to them, and it's an opportunity for them to meet another Crohn's patient for the first time and they can see they're not alone with the disease.
"It helps normalise their disease and can help them manage life better."