Seven percent of U.S. men and women aged 14–69 in 2009–2010 had oral human papillomavirus (HPV) infection, according to findings from the National Health and Nutrition Examination Survey (NHANES), and the evidence suggests that sexual contact was the primary means of transmission.¹ Eight percent of respondents who reported any sexual experience with a partner were infected, compared with 1% of those reporting none. In addition, the prevalence of infection rose significantly with individuals’ lifetime number of partners; it was nearly 11 times as great among those who had had more than 20 partners as among those who had had none. Men and heavy smokers had significantly higher rates of infection than women and nonsmokers, respectively, but differentials were much smaller.

NHANES conducts interviews and physical examinations among a nationally representative sample of civilian, noninstitutionalized men and women. In 2009–2010, approximately 5,500 participants provided oral rinse samples for HPV testing, and close to 5,000 answered interview questions on sexual behavior and potentially related characteristics. Researchers estimated HPV prevalence and compared estimates across various demographic, socioeconomic and behavioral subgroups in bivariate and multivariate logistic analyses.

Overall, 7% of respondents tested positive for any strain of oral HPV; the most prevalent type of infection (detected in 1% of participants) was HPV-16, which is associated with the vast majority of HPV-related oropharyngeal cancers. In unadjusted analyses, men had both a higher overall prevalence of oral HPV than women (10% vs. 4%) and a higher prevalence of HPV-16 (1.6% vs. 0.3%); blacks were more likely than whites to test positive for any strain of the virus (11% vs. 7%). Prevalence peaked at 7% among those in their early 30s and then at 11% among those aged 60–64. No significant differences were found by other demographic or socioeconomic characteristics. However, oral HPV prevalence was associated with substance use and with several measures of sexual behavior. Notably, 8% of respondents who had had sex (vaginal, oral or anal) were infected, compared with 1% who had not; similarly, prevalence increased significantly as lifetime and recent numbers of sexual partners rose.

In adjusted analyses, males continued to have a higher infection rate than females (prevalence ratio, 2.3). Additionally, prevalence rose with intensity of tobacco use; respondents who reported smoking more than 20 cigarettes daily had more than twice the prevalence of infection found among nonsmokers (2.1). Prevalence rose even more dramatically with lifetime number of opposite-sex partners for vaginal, anal or oral sex: It was more than three times as high among men and women reporting 2–5 partners, and close to 11 times as high among those reporting more than 20, as for those reporting no partners (3.2 and 10.7, respectively). Separate analyses by gender revealed that the association between tobacco use and oral HPV infection was stronger for women than for men, but the reverse was true for the association between lifetime number of partners and prevalence. In addition, women who were married (or cohabiting) at the time of the survey, or who had been married at some time, had a lower prevalence of infection than their never-married counterparts (0.4 for each).

Although NHANES data do not permit assessment of potential nonsexual means of virus transmission, the researchers believe that their findings, "taken together, … indicate that transmission by casual, nonsexual contact is likely to be unusual." Furthermore, they comment, despite the study’s limitations—including its cross-sectional design and reliance on self-reported data on sexual behavior—the results "have important research as well as public health implications." Because the researchers can only speculate on the reasons for the differences across age-groups and genders, they suggest that these results point toward important avenues for further study. Moreover, given that the efficacy of routine HPV vaccination in preventing oral infection is unknown, and the number of HPV-related oropharyngeal cancer diagnoses is approaching that of invasive cervical cancer, they conclude that trials on vaccine use for oral HPV prevention may be warranted.—D. Hollander