HPV (Human Papillomavirus) is the most common sexually transmitted disease, and it will infect 75% of young women before the age of 50, if they don’t get vaccinated. It’s the virus that causes genital and anal warts, abnormal pap smears, and cervical cancer. Even if you’re a virgin when you hook up with someone, you can end up with HPV- even if your partner has only slept with one other person.