Transmission of human papilloma virus, or HPV through saliva is still being studied as of 2011, although HPV infection of the oral mucosa is possible and is implicated in oral cancers. HPV is also suspected of causing cervical and anogenital cancers. Although only 10% of infections seem to involve cancer-causing strains of HPV, up to 75% of adults are or have been exposed to the virus, which usually resolves on its own. While HPV is common, it is also preventable.
Complete viruses such as rabies, Epstein-Barr and the flu show up consistently in saliva. While these viruses can spread through oral exposure from a bite or kissing, HPV has exhibited DNA traces at a variable rate. When studying transmission of HPV through saliva, researchers have discovered detection rates lower than those found in tissue.
A 2008 study in Greece found that detection rates were higher in those with inefficient immune system responses, however. Antibodies and antimicrobial proteins called lyzosomes are normally present in saliva and attack any intruders, keeping the bacterial and viral count down. Those with conditions that promote a dry mouth have less saliva and higher levels of microbes in their mouths; in addition, people with a compromised immune system are more susceptible to bacteria and viruses infecting them this way, including the spread of HPV through the patient's saliva.
The virus normally spreads through skin-to-skin contact, usually during sexual activity. The mucosa in the mouth and oropharyngeal complex is very similar to that of the genitals; HPV16, the same strain that causes cervical cancer, is also linked to oral cancer. A vaccine has been developed that targets four types of HPV, and it is recommended that females and males aged 9-26 be inoculated before any sexual contact takes place; the vaccine has been shown to prevent HPV infection before exposure. Early sex education aimed at preventing disease should include the possibility of spreading HPV through saliva.
HPV16 has also been found in younger people whose only risk factor for pharyngeal cancer is oral sex, rather than long-term tobacco or alcohol use. This implies that HPV16 is indeed spread through oral-genital contact, and thus may be contracted or passed through mucous membranes and fluids in the mouth. Education aimed at preventing disease should include the possibility of spreading HPV. Consistent use of latex condoms and other barrier devices that can be used during oral sex, such as dental dams, has been shown to reduce transmission of HPV through sexual activity.