" Sexually transmitted diseases are spread through any sexual contact during oral sex through the anus, penis, or vagina. The Centers for Disease Control and Prevention states that 1 in 2 sexually active people will contract an STD by the age of 25 and that 20 million STDs are contracted each year in the United States. The most common symptom of STDs is no symptom at all, so what is most important about STD prevention is ...