It has been known since at least 1964 that a viral infection can lead to autism. This CHS article records 4 ways autism can be caused including by viral infection: Vaccination Causes Autism – Say US Government & Merck’s Director of Vaccines
Live virus vaccines like MMR vaccine cause viral infections. Most people do not realise that 5% of those receiving the MMR vaccine develop symptoms of measles from the live virus in the MMR vaccine:
About 5% of immunocompetent children receiving their first dose of MMR vaccine have mild measles with fever and rash. The vaccine strain can cause severe measles in immunocompromised people.”
Additionally, the possibility that a vaccine can cause autism was known 38 years ago: A Vaccine Causing Autism Was First Reported in 1976.
This following new paper records what the authors believe is the first recorded case caused by an enterovirus.
Millions of children are infected by enteroviruses each year, usually exhibiting only mild symptoms. Nevertheless, these viruses are also associated with severe and life-threatening infections, such as meningitis and encephalitis. We describe a 32-month-old patient with enteroviral encephalitis confirmed by polymerase chain reaction in cerebrospinal fluid, with unfavorable clinical course with marked developmental regression, autistic features, persistent stereotypes and aphasia. She experienced slow clinical improvement, with mild residual neurologic and developmental deficits at follow-up. Viral central nervous system infections in early childhood have been associated with autism spectrum disorders but the underlying mechanisms are still poorly understood. This case report is significant in presenting a case of developmental regression with autistic features and loss of language improving on follow-up. To our knowledge, this is the first published report of enterovirus encephalitis leading to an autism spectrum disorder.