Step-by-step explanation:
Many of the diseases came from animals to humans.
Like, gonorrhea, it came from cattle. Syphillis also came from sheep and cattle.
The newest one, HIV, is believed to come from chimpanzee’s blood.
The first time, the world was presented to STD, was back in 1494, it is believed to originate from Colombian Exchange.
Chlamydia also came from Koalas.