The fact is that HIV in the US was narrowed down to a single immigrant from Haiti. And HIV is a disease. Autism is a condition that has relatively recently appeared in increasing numbers globally/world wide to children/toddlers around the age of 2 usually younger.
Cause unknown.
But it is not vaccines.
Probable cause of the increases?
Better diagnosis capability.
Like conditions now being diagnosed as within the autism spectrum.
Children predisposed towards autism.
http://en.wikipedia.org/wiki/Causes_of_autism
Even if the above 90% is correct how can it be triggered globally? What is happening to the baby in Japan, New York, Australia, and London?
Something is causing a significant increase in cases of autism within a narrow window of about 6 months to a year.