The human papilloma virus (HPV) causes genital warts. In women, the virus can infect the skin of the vulva (external genitalia), the skin around the anus, the vagina, and the cervix. Men may develop warts around the entrance to the urethra, on and under the foreskin, on the shaft of the penis, and around the anus. However, not everyone who is infected with HPV will develop warts.