Human papillomavirus (HPV) is one of the most common causes of sexually transmitted infection (STI) in the world. Health experts estimate there are more cases of genital HPV infection than any other STI in the United States. According to the Centers for Disease Control and Prevention (CDC), approximately 6.2 million new cases of sexually transmitted HPV infections are reported every year. At least 20 million people in this country are already infected. Genital warts (sometimes called condylomata acuminata or venereal warts) are the most easily recognized sign of genital HPV infection. Many people, however, have a genital HPV infection without genital warts.