Human Papillomavirus Type-Specific Prevalence

Genital Human Papillomavirus (HPV) infection appears to be the most common sexually transmitted virus and may be the most common sexually transmitted disease (STD) [1]. Prevalence of HPV infection in a population provides a measure of the percentage of individuals in that population that has new, persistent, or recurring HPV infection at a particular time and point. Prevalence represents an important measure of the disease burden within a population and can vary several-fold depending on the method of diagnosis and the demographic and behavioral determinants of the group under study [2]. For example, HPV prevalence in the United States appears to correlate with lower socioeconomic status [2, 3]. In longitudinal investigations, cumulative HPV prevalence has been shown to increase as the numbers of repeated test measurements increase [4–7]. This increase can be attributed to several factors including biological phenomena associated with transient and persistent HPV infections, sampling error, and overall assay characteristics. The reported prevalence of genital HPV infection suggests that age-specific prevalence rates parallel age-specific incidence rates. This would be expected if HPV infections are as a rule only transiently detectable. The prevalence of cervical HPV DNA peaks in early adulthood [8] and declines sharply with age [9, 10], increases with the number of different sexual partners, and in particular with the number of new sexual partners [11]. This observed age-related HPV prevalence may reflect a birth cohort effect or may suggest a role for immunological clearance with increasing age [12, 13].