A human papillomavirus (HPV) is a papillomavirus that infects the skin and mucous membranes of humans. It impacts the health of women far more than it impacts men. Approximately 130 HPV types have been identified. Some HPV types can cause warts (verrucae) or some types of cancer, while others have no symptoms. Most people who become infected with HPV do not even know they have it.

About 30-40 HPV types are typically transmitted through sexual contact and infect the anogenital region. Some sexually transmitted HPV types may cause genital warts. Persistent infection with "high-risk" HPV types — different from the ones that cause warts — may progress to precancerous lesions and invasive cancer.Fact: date=February 2008 HPV infection is a cause of nearly all cases of cervical cancer. However most infections with these types do not cause disease.

A cervical Pap smear is used to detect cellular abnormalities. This allows targeted surgical removal of condylomatous and/or potentially precancerous lesions prior to the development of invasive cervical cancer. Although the widespread use of Pap testing has reduced the incidence and lethality of cervical cancer in developed countries, the disease still kills several hundred thousand women per year worldwide. HPV vaccines, Gardasil and Cervarix, which prevent infection with some of the sexually transmitted HPV types that cause the most disease may lead to further decreases in the incidence of HPV-induced cancers.

United States

HPV is estimated to be the most common sexually transmitted infection in the United States. Most sexually active men and women will probably acquire genital HPV infection at some point in their lives. *Note: The authors state on page S17 "Overall, these DNA-based studies, combined with measurements of type-specific antibodies against HPV capsid antigens, have shown that most (>50%) sexually active women have been infected by one or more genital HPV types at some point in time." The American Social Health Association reported estimates that about 75-80% of sexually active Americans will be infected with HPV at some point in their lifetime. By the age of 50 more than 80% of American women will have contracted at least one strain of genital HPV.

It was estimated that in the year 2000, there were approximately 6.2 million new HPV infections among Americans aged 15-44; of these, an estimated 74% occurred to people between ages 15-24. Of the STDs studied, genital HPV was the most commonly acquired.

Estimates of HPV prevalence vary from 14% to more than 90%. One reason for the difference is that some studies report women who currently have a detectable infection, while other studies report women who have ever had a detectable infection. Another cause of discrepancy is the difference in strains that were tested for.