Expert answer:
Unprotected oral sex is one of the STD (Sexually Transmitted Diseases) contagion ways. You are having oral sex on your partner, or your partner having oral sex on you.
A person only transmits a disease if that disease is transmissible (contagious), if there is contact or means of transmission and if the person is contaminated.
HPV example: It is a disease caused by a virus that is transmissible, you only get HPV if you have contact with the virus hosted in another person's body, and the person can only transmit HPV if they have HPV.
