How did syphilis diffuse across europe and africa of the americas never gave it to africa?

Syphilis is a disease which spreads mainly due to sexual contact and starts as a painless sore There are two theories regarding it but prominent one is The Columbian theory This theory states that during the voyage of Columbus maany of his crew members came into contact with syphilis bacteria and later when they joined the army of King Charles VIII it spread in euriope In the second theory people believe that there were symptoms of syphilis even before the Columbian Voyage and the symptoms of syphilis in its tertiary form were described by Hippocrates in Classical Greece