ABSTRACT
Almost all anogenital warts are caused by types 6 and 11 of the human papilloma virus (HPV). These types are different from those that cause genital cancers (includes types 16, 18, 31 and many more). They are also different from the types that cause warts on the hands (usually type 1), although there are occasional reports of apparent transmission of type 1 HPV from the hand to genital skin leading to the growth of warts. This is more likely if the person is immunosuppressed or a child. In one study, 2% of genital warts in adults were caused by HPV type 1-4 compared to 15% in children. Because HPV types 6 and 11 are site specific due to a preference for some feature of the genital epithelium, they are transmitted directly from one person’s genitals to another’s. Penetrative sex is not necessary and condoms offer only modest protection against transmission.
