According to officials in the nation's regulatory agencies, the main obstacle to proving or disproving a link between the autism epidemic and the mercury-based preservative, thimerosal, that was contained in childhood vaccines until a few years ago, and is still in flu vaccines, has been the inability to find a large enough group of people who have never been vaccinated to compare with people who have.

In fact, a few months ago, CDC officials claimed that such a study would be nearly impossible. On July 19, 2005, the CDC held a Media Briefing on the topic of vaccines and child health. On the issue of government research on autism, a reporter asked CDC Director, Dr Julie Gerberding: "are you putting any money into clinical studies rather than epidemiological studies, to verify or disprove the parents' claim about a particular channel, a particular mechanism by which a minority of genetically suspectable kids are supposed damaged?"

Gerberding replied: To do the study that you're suggesting, looking for an association between thimerosal and autism in a prospective sense is just about impossible to do right now because we don't have those vaccines in use in this country so we're not in a position where we can compare the children who have received them directly to the children who don't.

Dr Duane Alexander, of the National Institute of Health, agreed and said: It's really not possible ... in this country to do a prospective study now of thimerosal and vaccines in relationship to autism. Only a retrospective study which would be very difficult to do under the circumstances could be mounted with regard to the thimerosal question.

However, Dan Olmsted, investigative reporter for United Press International, and author of the Age of Autism series of reports, appears to have solved this problem when he came up with the idea of checking out the nation's Amish population where parents do not ordinarily vaccinate children.

First he looked to the Amish community in Pennsylvania and found a family doctor in Lancaster who had treated thousands of Amish patients over a quarter-century who said he has never seen an Amish person with autism, according to Age of Autism: A glimpse of the Amish on June 2, 2005.

Olmsted also interviewed Dick Warner, who has a water purification and natural health business and has been in Amish households all over the country. "I've been working with Amish people since 1980," Warner said.

"I have never seen an autistic Amish child -- not one," he told Olmsted. "I would know it. I have a strong medical background. I know what autistic people are like. I have friends who have autistic children," he added.

Olmsted did find one Amish woman in Lancaster County with an autistic child but as it turns out, the child was adopted from China and had been vaccinated. The woman knew of two other autistic children but here again, one of those had been vaccinated.

Next Olmsted visited a medical practice in Middleburg, Indiana, the heart of the Amish community, and asked whether the clinic treated Amish people with autism.

A staff member told Olmsted that she had never thought about it before, but in the five years that she had worked at the clinic she had never seen one autistic Amish.

On June 8, 2005, Olmsted reported on the autism rate in the Amish community around Middlefield, Ohio, which was 1 in 15,000, according to Dr Heng Wang, the medical director, at the DDC Clinic for Special Needs Children.

"So far," according to Age of Autism, "there is evidence of fewer than 10 Amish with autism; there should be several hundred if the disorder occurs among them at the same 166-1 prevalence as children born in the rest of the population."

In addition to the Amish, Olmsted recently discovered another large unvaccinated group. On December 7, 2005, Age of Autism reported that thousands of children cared for by Homefirst Health Services in metropolitan Chicago have at least two things in common with Amish children, they have never been vaccinated and they don't have autism.

Homefirst has five offices in the Chicago area and a total of six doctors. "We have about 30,000 or 35,000 children that we've taken care of over the years, and I don't think we have a single case of autism in children delivered by us who never received vaccines," said Dr Mayer Eisenstein, Homefirst's medical director who founded the practice in 1973.

Olmsted reports that the autism rate in Illinois public schools is 38 per 10,000, according to state Education Department data. In treating a population of 30,000 to 35,000 children, this would logically mean that Homefirst should have seen at least 120 autistic children over the years but the clinic has seen none.

It looks like the problem is finally solved. Thanks to autism's Dick Tracy, the government now has thousands of unvaccinated people to compare to people who were vaccinated.