An increasing number of Ontario children are being diagnosed with the serious and lifelong condition known as inflammatory bowel disease, a new study has found.

The study, released Wednesday by the Institute for Clinical Evaluative Sciences, showed a 33 per cent rise in the prevalence of IBD in Ontario children from 1994 to 2005, and concludes that the province has one of the highest rates of childhood-onset IBD in the world. 

'It still is extremely rare in children under 10, but it's definitely increasing and we need to know why it's increasing.' — Dr. Eric Benchimol

"Over the last 15 years or so, we've noticed an increased incidence in inflammatory bowel disease in our clinics in Ontario," said Eric Benchimol, the principal investigator and a pediatric gastroenterologist at Toronto's Hospital for Sick Children.

"This [study] was really aimed at filling a gap in our knowledge as to how frequent it is and what the trends are over time."

In the under-18 age group, prevalence has risen from 42.1 per 100,000 children in 1994 to 56.3 per 100,000 children in 2005.

The risk of developing IBD has remained about the same for teenagers and tweens, but the study, published on the website of the journal Gut, found a rising incidence of Crohn's disease in children under 10 years old.

"It still is extremely rare in children under 10, but it's definitely increasing and we need to know why it's increasing," Benchimol said.

At any given time, he said, there are around 1,600 children under 18 in Ontario with inflammatory bowel disease. Of those, 200 to 300 are under the age of 10.

IBD is the umbrella term for ulcerative colitis, which is inflammation of the large intestine, and Crohn's disease — inflammation that can affect any part of the gastrointestinal tract.

Symptoms can include swelling, nausea, abdominal pain and diarrhea, bloody stool and an urgent need to get to the washroom.

Causes elusive

Medications are available, and surgery is sometimes an option, but there is no cure. There are often periods of time when patients are asymptomatic in between flare-ups.

Benchimol said scientists aren't 100 per cent sure what causes inflammatory bowel disease, but there's a genetic risk factor, and increased immigration from certain parts of the world may be part of the reason for the rise in Ontario.

Over the last 20 years or so, he said there's been a higher rate of South Asian patients from Sri Lanka, Pakistan and India.

"And a study out of Vancouver has shown previously that South Asian patients, after they arrive to Canada, have a higher rate as children of developing IBD," he said.

"So it's possible that when they're still in South Asia, the rate is quite low,…but once they arrive here, they're exposed to something in the environment that may be kicking off this inflammation."

As well, Benchimol said environmental factors could be at play, and doctors may be recognizing IBD and diagnosing the condition earlier.

George Tolomiczenko, executive director of research for the Crohn's & Colitis Foundation of Canada, welcomed the new data, noting that the study will help focus more research on what might be propelling these rates.

"The rate of new cases is alarmingly high for Crohn's disease and ulcerative colitis in Ontario," he said from near Summerside, P.E.I., where he was on vacation.

Young children with the condition might complain of tummy aches, he said, and because of the symptoms, they might not get as much nourishment and therefore not grow as well.

"There are other kids who up to their early teens are very healthy, athletic, sort of robust young people, then the symptoms really kind of knock them off that track," he said.

Higher rates in Western countries 

Tolomiczenko wondered what is going on in Ontario that might make people more vulnerable.

"Every one of us is colonized from a very early age by an assortment of bacteria, viruses and fungi. We live in harmony for the most part, but part of the understanding of Crohn's disease is that the balance is thrown off," he noted.

Benchimol said that about 250,000 adults in Canada have IBD.

"We do know that the Western lifestyle in general makes people more predisposed to IBD," he said.

"There are much higher rates of IBD in Westernized nations as opposed to other nations. But we don't know yet what causes it, what that environmental factor is."

Kevan Jacobson, a pediatric gastroenterologist at B.C. Children's Hospital, said the new data are helpful because they reaffirm that inflammatory bowel disease is a problem in Canada.

"We don't have incidence, prevalence rates for every province, specifically for children 16 years of age and under," he said.

"We have more data to allow us to guesstimate across the country what the incidence and prevalence of disease is in childhood and adolescence."

His own work puts the prevalence at about 35 per 100,000 children in British Columbia, he said.