More than 40 HPV types can be easily spread by contact with infected skin or mucous membranes, through vaginal, anal, and oral sex. The other HPV types are responsible for non-genital warts, but are not sexually transmitted.
Sexually transmitted HPV types fall into two categories:
- Low-risk HPVs: Do not cause cancer but can cause skin warts (technically known as condylomata acuminata) on or around the genitals and anus. For example, HPV types 6 and 11 cause 90% of all genital warts. HPV types 6 and 11 also cause benign tumors to grow in the air passages leading from the nose and mouth into the lungs (known as respiratory papillomatosis.)
- High-risk HPVs: Can cause cancer. About a dozen high-risk HPV types have been identified. Two of these, HPV types 16 and 18, are responsible for most HPV-caused cancers. About half of the 14 million annual infections are with a high-risk HPV type.
Most of the HPV-positive non-cervical cancers develop in men.
Most high-risk HPV infections occur without any symptoms, go away within 1 to 2 years, and do not cause cancer. Some HPV infections, however, can persist for many years. Persistent infections with high-risk HPV types can, if untreated, lead to cancer.
The HPV positive person can infect anyone they have sexual contact with at any time. All forms of sexual contact (oral, anal, vaginal) can transmit the virus. A person can have an HPV infection without symptoms and when their only sexual contact was with an HPV-infected person many years prior.
The Food and Drug Administration (FDA) has approved three vaccines to prevent HPV infection: Gardasil®, Gardasil® 9, and Cervarix®. These vaccines provide strong protection against new HPV infections, but they are not effective at treating established HPV infections or the diseases which are caused by HPV. The FDA recommends both boys and girls ages 9-11 be vaccinated.
Keep in mind, the most effective of the vaccines, Gardasil® 9, works on up to 9 types of HPV, but there are 35 which can live in the genital tract.