Types of HPV
High-Risk Types of HPVHPV research scientists have separated HPV types into those that are more likely to develop into cancer and those that are less likely. The so-called "high-risk" types are more likely to lead to the development of cancer, while "low-risk" viruses rarely develop into cancer.
The sexually transmitted varieties of high-risk HPV include:
A few others may also be included on this list. These high-risk HPVs cause growths that are usually flat and nearly invisible, as compared to the warts caused by types HPV-6 and HPV-11.
Up to 70 percent of cervical cancer cases are caused by HPV-16 and HPV-18. These are two of the types that the HPV vaccine (sold under the brand name Gardasil®) protects against. The other two are low-risk types of HPV (types 6 and 11), which cause up to 90 percent of genital warts cases.
(Click High-Risk HPV for more information.)
Low-Risk Types of HPVLow-risk HPV types can cause no symptoms or may cause conditions such as genital warts, but do not cause cervical cancer. Warts can form weeks, months, or even years after sexual contact with a person who has genital HPV.
It's also possible that warts may never appear. In fact, most people with low-risk types of genital HPV never know they are infected because they don't get warts or any other symptoms (see HPV Symptoms).