Behavioral and sociodemographic risk factors for serological and DNA evidence of HPV6, 11, 16, 18 infections.

Introduction: Risk for HPV6/11/16/18 infections in young sexually active, behaviorally low-risk females is not well described and may inform public policy. Methods: To assess exposure risk for HPV/6/11/16/18 among 16–23 year old low-risk females, data for 2409 female clinical trial participants were evaluated. Baseline visit self-reported sexual, behavioral and demographic characteristics; and results from HPV genotyping and serology, and other clinical laboratory assays were analyzed. All subjects reported <5 lifetime male sexual partners and no prior abnormal cytology at baseline. Results: While 98% (2211/2255) were naïve to HPV16 or 18 and 99.6% (2246/2255) were naïve for 1–3 index HPVs, 27% (616/2255) showed antibody, DNA or both for ≥1 index HPV. While 18% (409/2255) tested HPV16- or -18-antibody- or -DNA-positive, only 2% (44/2255) tested positive for both types. Against this high background, other sexually transmitted infections (STIs) were uncommonly detected, suggesting low sexual risk-taking behavior. The adjusted analyses showed race, age, alcohol consumption, current Chlamydia trachomatis (chlamydia) and Trichamonas vaginalis (trichomoniasis), bacterial vaginosis (BV), number of lifetime male sex partners predicted positive index-HPV antibody test results. However, only the number of male sex partners predicted positivity for HPV6/11- and 16/18-DNA, and chlamydia infection predicted positivity for HPV6/11-DNA alone. Conclusions: Taken together, type-specific HPV-DNA and -antibody evidence of HPV6/11/16/18 infections among behaviorally low-risk 16–23 year old females is high. Since almost all participants would have benefited by either currently available bivalent or quadrivalent vaccine strategies, delaying vaccination beyond menarche may be a missed opportunity to fully protect young females against HPV6/11/16/18 infections and related dysplasias. Early diagnosis and treatment of chlamydia and trichomonas may be important in HPV pathogenesis.