My guess would be ...Imported from Mexico.
Oh without a doubt it certainly is.
They’re just infecting the people that Americans are unwilling to infect themselves.
My guess would be modern young idiotic progressive parents not getting their kids vaccinated because they have heard health quacks saying vaccines cause autism.
Nobody knows what causes autism, although it is most certainly not vaccines, but these people all listen to hippie loony quacks who preach that “sugar is poison,” blah, blah, blah.
Unvaccinated kids have actually been a big problem in exclusive private schools.