Actually, drug rersistant syphylis had already passed to North America from Asia by that time, and Americans just had no clue about the slow killers that destroy you slowly.
Aides wasn’t hear yet, and drug resistant Gonorhea wasn’t here yet...but things were out there.
Sometimes ignorance is bliss. Until it bites.
I wasn't around then, so please let me enjoy a few minutes of ignorance.
Although I suspect many of the icky diseases you mentioned weren't “main stream” in the 70’s.