The Human Papilloma virus has over 100 strains (subtypes). Types 6 and 11 are the main cause of genital and anal warts (venereal warts). Types 16 and 18 are the main cause of anal and cervical cancer (in women), and in rarer cases may also cause cancer of the penis, vagina, vulva, head and neck. Common warts on the hands and feet are NOT from the same HPV subtypes, and these do not affect sexual health.
Not everyone with HPV gets warts, and they can take a long while to develop after infection (up to a year), but the virus can still be transmitted even if warts are not present.
HPV is a very common virus (in about 30% of the population) and most sexually active adults have likely been exposed to HPV. Although HPV can last in the body for years or decades without any symptoms (in a latent state), many people will naturally clear the virus over time (within a year or so, although this is less likely for the HPV cancer risk types). Its only when the immune system can’t fight off the infection that some strains can lead to cancer, but very few high risk HPV cancer types do lead to cancer (although it’s hard to predict, and that is why check-ups/screening are so important).
In most people who have been exposed to HPV infection it does not cause morbidity (health concerns), but it can be a concern where there is immune compromise and inflammation (such as from HIV) when HPV can reactivate. HIV-positive people co-infected with HPV have much higher incidence rates of anal and cervical cancers (and pre-cancerous lesions) than those without HIV; although the prevalence (number of HIV-positive people) this affects remains low, but is increasing. That said, in most cases pre-cancerous lesions (low grade lesions) disappear on their own (without treatment) and do not lead to cancer (high grade lesions).
Transmission: HPV can be contracted during non-condom anal, vaginal or oral sex, and by close physical contact with the genital area or by sharing sex toys, even if the infected partner has no obvious signs or symptoms of HPV. Contact with warts (if they are present) is a risk as well. Using condoms, and effectively washing sex toys between partners, will decrease the chances of getting HPV.
Prevention of HPV-associated cancers is achieved through early detection (screening) and medical management, to prevent progression to invasive cancer. For anal cancer, an annual Digital Anal-Rectal Examination (DARE) and examination by a sexual health physician is recommended for HIV-positive men, to check for the presence of anal lesions. A yearly PAP smear (Papanicolaou test) is also recommended for HIV-positive women to detect cervical lesions. Individual needs vary, so speak to your doctor about recommended screening frequency and screening procedures.
Like all cancers, it is important to avoid or quit smoking, as smoking highly elevates cancer risk, and also reduces the likelihood of clearing the HPV infection. For women, some oral contraceptives and IUDs have been shown to increase the risk of HPV-associated cancers. Speak to your doctor about cancer risk prevention.
Prevention of HPV-associated warts includes avoiding touching them because they can be contagious. Warts are best removed by your doctor (often freeze removed or by minor surgery) or they can be treated with topical creams (e.g. Aldara [imiquimod]), but they may re-emerge. Removing the warts does not remove the infection.
Two vaccines are available and funded (Cevarix & Gardasil) for girls and boys (to age 13) which protects from acquiring strains of HPV that cause cervical and anal cancer and warts (Gardasil only). In practice, some sexual health doctors may offer the vaccine to women and men to the age of 26 (depending whether you have been exposed to HPV already). If you already have HPV then the vaccine is of no value, as it will not alter or treat any pre-existing HPV infection or the development of any consequences of the infection. However, some research has shown that even if you have had prior HPV exposure you may still benefit from the HPV vaccination, although the therapeutic effect is uncertain. Further study is needed in this area.
About Anal Cancer (for Gay Men):
About HPV (for women):
About HPV Vaccination: http://www.immunise.health.gov.au/internet/immunise/publishing.nsf/Content/immunise-hpv
About HPV vaccination in HIV-positive and HIV-negative gay men: