Prevalence of Human Papillomavirus Infection in Adolescent Girls Before Reported Sexual Debut

Houlihan et al present data on the prevalence of human papillomavirus (HPV) infection among 474 adolescent girls aged 15–16 years in Tanzania who reported no previous sexual intercourse. Despite no reported history of sex, a nonnegligible fraction of girls (8.4%) tested positive for HPV infection, using a highly sensitive polymerase chain reaction assay from nurse-assisted, self-administered cervicovaginal specimens. Global data on the prevalence of HPV infection among adolescents worldwide are extremely limited [1]. Therefore, these data from Tanzania are important because they are among the first to examine HPV infection prevalence among female adolescents and are from sub-Saharan Africa, which has one of the highest incidence rates of invasive cervical cancer in the world [2]. As cited by the authors, the laboratoryconfirmed prevalence of HPV infection was relatively higher than that previously observed in studies from Europe, Australia, and the United States, which found extremely low or no HPV detection among female participants reporting no previous sexual intercourse. The 2010 Tanzania Demographic and Health Survey (TDHS) documented a self-reported median age at first intercourse of 17.4 years, with an estimated 15% of women having had sexual intercourse by 15 years of age [3]. This latter TDHS estimate of previous sexual intercourse is somewhat higher than that observed by Houlihan et al (19% among participants aged 15–16 years). Together, the data suggest that, in the study by Houlihan et al, the HPV infection prevalence of approximate 9% among female adolescents before reported sexual debut is partially attributable to the underreporting of previous sexual intercourse by study participants. This potential underreporting is likely due to social desirability and study consent procedures requiring parental consent, which may have created an environment in which daughters were relatively uncomfortable to disclose their previous sexual activity. The cervicovaginal prevalence of HPV infection was the higher among participating Tanzanian female adolescents who reported a history of vaginal douching, with the highest risk of HPV infection observed with more-frequent vaginal cleansing. Although the weight of the evidence suggests a positive association between pelvic inflammatory disease and the practice of douching [4, 5], data have been relatively inconsistent for associations between vaginal douching and Chlamydia trachomatis infection [5], human immunodeficiency virus infection [6], HPV detection [7, 8], and cervical cancer [5]. This merits further investigation with more-detailed examination of douching practices and formulations. A highly plausible alternative explanation is that the reporting of vaginal douching among female adolescents in the study by Houlihan et al represented a proxy of unreported sexual activity rather than a causal risk factor for HPV infection per se. These data from Houlihan et al have implications for the global implementation of prophylactic HPV immunization programs, particularly given that the Global Alliance for Vaccination and Immunization (GAVI) is now providing access to affordable HPV vaccination for GAVI-eligible, lower-income countries [9]. The recently released summary report of the US President’s Cancer Panel, Accelerating HPV Vaccination Uptake: An Urgency for Action to Prevent Cancer, recommended as part of its global focus to “continue its collaboration with and support of GAVI to facilitate HPV vaccine introduction and uptake in lowincome countries” [10]. Several GAVIeligible countries, including Tanzania, have initiated HPV vaccination demonstration projects aimed to prove the field-based capacity to successfully implement population-based HPV immunization programs for adolescents. The primary target population for HPV immunization for public health programs should be non–sexually active, preadolescent females, given that current Received and accepted 24 March 2014; electronically published 16 April 2014. Correspondence: Jennifer S. Smith, PhD, Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, 2103 McGavran-Greenberg, Campus Box 7435, Chapel Hill, NC 27599 (jennifers@unc.edu). The Journal of Infectious Diseases 2014;210:835–6 © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals. permissions@oup.com. DOI: 10.1093/infdis/jiu207