“You can get AIDs only by sex with HIV infected person.”
You’re a self-proclaimed genius.
You can get AIDS/HIV via blood transfusions with tainted blood.
You can get AIDS/HIV via exposure to other bodily fluids.
I never needed blood transfusion but had many sex partners during my bachelor years in Chicago metro, so the transfusion aspect escaped my mind.
On the other hand I will venture WAG that 90%+ HIV is transmitted via sex, especially by gays.
As a life long practicing engineer, quantitative levels are much more critical.