There has been a threefold increase in autism rates over the past six years, according to the preliminary results of a survey carried out for the Irish Society for Autism.
The survey, which is being carried out in the Dublin, Wicklow and Kildare region, shows an autism rate close to 15 out of every 10,000 children. Six years ago, the survey showed a rate of five cases for 10,000 children.
Autism is a developmental disorder which usually becomes apparent before the age of three. It mostly affects language, communication and behavioural skills.
Mr Pat Matthews, ISA executive director, stressed these were just preliminary results but said it was worrying.
"It's a very significant increase, for whatever reason. There may be a lot of factors playing a role, such as better diagnosis services and greater awareness of autism. But these factors still do not fully explain the increase."
Last November, the Joint Oireachtas Committee on Health was told that an unpublished survey had found 33 cases of childhood autism in a population of 13,000 in one Cork region.
Dr Andrew Wakefield, a British researcher on autism, has pointed to a dramatic increase in autism rates in the US. One state recorded an autism rate of one in 32 children between six and 18 years, he told the joint committee in March.
Some parents' groups had made submissions linking the three-in-one MMR vaccine to autism.
The Department of Health has strongly rejected this and has urged parents to use the MMR vaccine. The committee is expected to publish its findings on its vaccination hearings in the next few weeks.
Dr Wakefield said he was not anti-vaccine but recommended parents be offered the option of having their children vaccinated separately for measles, mumps and rubella.
There was a question mark over the link between autism and the MMR vaccine, he said, and while this remained, the option of single vaccines should be available.
The Irish Society for Autism also emphasised it was not anti-vaccine but would like to see the option of single vaccines.
Mr Matthews said that where parents were concerned that their children fell into the very small "vulnerable sub-group" they should be given the option of three separate vaccines. Children with a family history of autism and neurological disorders fell into this category.
Mr Matthews also called on the Department of Health to provide counselling for parents of susceptible children, before vaccination. "There is no support whatsoever for these parents," he said.
