In fall 1995, the FDA approved two automated readers for the rescreening of cervical cells evaluated as normal on the initial screen. HPV is a group of at least 70 different types of viruses . HPV infection is more common in younger age groups, particularly in women in their late teens and twenties. Because HPV is spread mainly through sexual contact, risk increases with number of sexual partners. Women who become sexually active at a young age, who have multiple sexual partners, and whose sexual partners have other partners are at increased risk.
Nonsexual transmission is also possible.
The virus often disappears but may remain detectable for years after infection. Next in prevalence is HPV-18. Together these account for nearly 90 percent of HPV infections in cases of HSIL and cervical cancer. The NIH Consensus Conference on Cancer of the Cervix and the World Health Organization have concluded that there is a cause and effect relationship between HPV and cervical cancer. Scientists continue to study other factors that may also be required for the development of cancer, such as changes in the immune system.