What are sexually transmitted diseases/infections?
A few decades ago, sexually transmitted diseases were relatively simple: there was gonorrhea, which was thought to be most common; then syphilis, which was less common, and non-gonococcal urethritis, which could only be determined to be present on clinical grounds, but where many authorities who questioned whether it even existed. AIDS did not exist and herpes was a rare condition.
Today we know that most venereal diseases are due to chlamydia, which is caused by Chlamydia trachomatis. Others are due to Mycoplasma genitalium or Ureaplasma urealyticum. AIDS and hepatitis C are a lot more common.
Sexually transmitted diseases/infections include: