Specifically it was folded into ASD in the DSM-5, the 2013 edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders. The change was rather controversial, and in any case the DSM is only considered gospel in the USA.

(As a person with autism/Asperger's, I'm not sure I have a strong opinion. Asperger's is clearly at least related to autism, and the autistic spectrum is a pretty broad umbrella anyway.)