In the wake of a move
Genital human papillomavirus (HPV) infections are sexually transmitted infections of increasing public health importance. Known for years as the cause of genital warts, there is a growing body of evidence demonstrating the etiological association with a variety of anogenital cancers. Further-more,
genital HPV infections are widespread among adults who have been sexually active and are estimated to have the highest incidence of any sexually transmitted disease (STD) in the U.S.
Although cervical cancer screening programs have been implemented in the U.S. and other developed countries for decades, public health agencies have not established programs for primary prevention of genital HPV infection nor attempted to modify existing cancer prevention programs to take advantage of the associated role of HPV.
Because genital HPV infection is not a reportable condition (This may be changing soon, read Breast And Cervical Cancer Treatment Bill Approved By House in today's Vidyya), assessments of its magnitude are derived by extrapolation from epidemiological studies measuring current infection by detection of HPV DNA, with the most sensitive method being the polymerase chain reaction (PCR) technique, and approximating lifetime infection by measuring HPV antibody in serologic assays. While results have varied by population studied and sampling and detection methods used, overall they indicate that among sexually active women, over 50% have been infected with one or more genital HPV types, approximately 15% have evidence of current infection, 50-75% of which is with high-risk types, and 1% have genital warts. These findings are supported by a recent study of incident HPV infection in young women, which documented a 36-month incidence rate of 43%. Men have been less well-studied, in part because sites and methods of mucosal sampling are less well-standardized.
Levels of current infection in men as measured by PCR appear to be similar to women, while levels of lifetime infection as measured by serum antibody appear to be lower in men, possibly related to gender differences in the development of antibody after infection. A recent assessment of the magnitude of various STD in the U.S. estimated an annual incidence of genital HPV
infection of 5.5 million and a prevalence of current infection (detectable HPV DNA) of 20 million. The majority of infections with all types appear to be subclinical, detectable neither by physical exam nor cytology, but only by the use of HPV DNA detection tests.
The disease burden created by genital HPV infection is high. Worldwide, there are estimated to be 400,000-500,000 cases of cervical cancer per year. Most cases occur in developing countries without cervical cancer prevention activities; however, even in industrialized countries, where
rates have fallen by up to 75% since the introduction of Pap smear screening programs, the disease burden is still considerable. In the U.S., for example, incidence rates are currently 8.3/100,000, with approximately 14,000 cases and 5000 deaths annually, despite the performance of an estimated
50 million Pap smears per year. In addition, as a result of these screening activities, an estimated 2.5 million Pap smears with low-grade abnormalities (e.g., atypical squamous cells of undetermined significance–ASCUS, atypical glandular cells of undetermined significance–AGUS, and LSIL) and 200,000-300,000 Pap smears with HSIL are detected annually in the U.S. While
these lesions cause no clinical morbidity apart from that resulting from treatment, their magnitude is important because of the health care costs they generate.
Despite the absence of prevention programs, the incidence of other HPV-related cancers are 5-10 fold lower than that of cervical cancer, with the exception of anal cancer in homosexual men, which was estimated to be
12-35/100,000 prior to the onset of the AIDS epidemic and which may be higher now. Estimates for genital warts are less precise than those for cancer because of the absence of case reporting and because they often recur after treatment; however, limited data suggest that in the U.S. incidence rates may be as high as 100 per 100,000 with a prevalence of 1.4 million.
Finally, estimates for RRP, a disease of both children and adults in which papillomas of the larynx and upper respiratory tract cause hoarseness and respiratory obstruction, are similarly imprecise, with estimated
incidence rates of 0.4 to 1.2 per 100,000 children.
Only limited attempts have been made to estimate the annual cost burden of genital HPV infection in the U.S. Existing estimates range from $1.6 billion to $6 billion, making genital HPV the second most costly STD after HIV infection; these estimates do not include costs for management of RRP, indirect costs (i.e., lost time and wages), or intangible costs (e.g., emotional pain, anxiety, disrupted relationships).
Download a copy of the full recommendation report: Prevention of Genital HPV
Infection and Sequelae.