Autism rare before mass DPT vaccination
Autism increase

See: Autism and genetics  change in diagnosis Leo Kanner

[2015 Aug] The Age of Autism Week In a Number: 1938  "Olmsted and Blaxill (again) show that Autism had a start date, and it was after Eli Lilly invented and began selling a water soluble form of mercury in fungicide and vaccine preservation."

[vid] How Mercury Triggered The Age Of Autism

An Extremely Rare Disorder

“Since 1938, there have come to our attention a number of children whose condition differs so markedly and uniquely from anything reported so far that each case merits—and, I hope will eventually receive—a detailed consideration of its fascinating peculiarities....

“These characteristics form a unique “syndrome”, not heretofore reported, which seems to be rare enough, yet is probably more frequent than is indicated by the paucity of observed cases.”
-Leo Kanner, “Autistic disturbances of affective contact”, Nervous Child, 1943

“The fact that an average of not more than eight patients per year [over twenty years] could be diagnosed with reasonable assurance as autistic in a center serving as a sort of diagnostic clearinghouse, speaks for the infrequency of the disease, especially if one considers that they recruit themselves from all over the North American continent...”
-Leo Kanner, “The specificity of early infantile autism” Acta Paedopsychiatrie, 1958

Kanner was the world’s leading expert in child psychiatry. He was the leader in the field at Johns Hopkins. In 1935, he wrote a textbook that was over 500 pages long that had detailed, exhaustive descriptions of every possible malady of childhood that he and his colleagues had ever seen. There’s not one mention of autism in that 1935 textbook.
    When he wrote his paper, published in 1943, he said, “Since 1938 there have come to our attention a number of children whose condition differed so markedly and uniquely from anything seen before that each case merits – and I hope will receive – a detailed investigation of its fascinating peculiarities.” So here is the world’s leading expert on child psychiatry who has already written a textbook. In 1943 he writes that in the last five years, we’ve started to see children and they’re unlike any children we’ve ever seen before.
    And he only saw 11 of them. And one of the things we’ve described is that people came from all over the country, all over the world to visit at Hopkins. The notion that autism was around at a rate of 1 in 100 or even a fraction of that is absurd. So the genetic argument at this point collapses on its face. It doesn’t even meet the basic tests of logic and common sense.
[2010 Sept] Interview with Dan Olmsted, Mark Blaxill: 'Age of Autism-Mercury, Medicine, and a Manmade Epidemic'