The prevalence of human papillomavirus (HPV) infection in a sample of female college students in Montreal and their male partners was 4.5 times as high among individuals whose partner was HPV-positive as among those whose partner was not infected; indeed, partner’s infection status was the strongest predictor of current HPV infection.1 After condom use and lifetime number of partners were adjusted for, women and men were substantially more likely to test positive for a specific type of HPV if their current partner was infected with that type than if their partner was not (odds ratio, 55.2 and 58.7, respectively). In addition, for men but not for women, increased condom use was associated with reduced odds of HPV detection (0.6–0.9).
HPV is thought to be highly transmissible; it is therefore likely that transmission occurs relatively soon after a couple first engages in intercourse. Because previous couple-based studies on HPV transmission have studied only couples in long-term relationships, the authors sought to examine HPV infection among new couples, closer to the transmission event and before the infection could have resolved. As part of a longitudinal study on HPV infection and transmission, a volunteer sample of women aged 18–24 attending -junior college or university in Montreal and their male partners were recruited between May 2005 and August 2008. The women were eligible if they were not pregnant or planning to become pregnant in the next 24 months, had an intact uterus and no history of cervical cancer or lesions, and had been having sex with their current male partner for less than six months; eligible males were aged 18 or older. The final sample consisted of 263 couples.
The analysis used data gathered at baseline, when each participant completed a computerized questionnaire that asked about social, demographic and sexual history characteristics. Partners’ responses were averaged for analysis of couple-based characteristics. In addition, women provided self-collected vaginal swabs; a clinician collected samples of epithelial cells from men’s penis and scrotum. The outcome of interest was presence of HPV in genital specimens. The overall and type--specific HPV prevalence rates were calculated, as were overall prevalence rate ratios by partner’s infection status, respondent’s lifetime number of partners and couple’s frequency of condom use. Logistic regression was used to assess predictors of type-specific HPV infection.
The median age of the respondents was 21 for women and 22 for men; 98% of the women and 71% of the men were enrolled in school. The median lifetime number of vaginal sex partners was five for both sexes, and similar proportions of men and women reported having been monogamous since the start of their current relationship (86% and 85%, respectively). At baseline, couples had been engaged in vaginal sex for a median of 3.9 months. Two-thirds of couples used condoms at least some of the time, including one in five who were consistent users.
HPV of at least one type was detected in 56% of women and 56% of men (although couples were not necessarily concordant for HPV types). Both partners were HPV-positive in 48% of couples; both were HPV-negative in 36%. The mean number of HPV types among participants with any infection was 2.8 for both men and women.
Men and women whose partner was HPV-positive had a prevalence rate 4.5 times that of men and women whose partner was HPV-negative. For both sexes, prevalence increased with lifetime number of vaginal sex partners. Prevalence decreased with greater condom use, but for men only.
By far, the strongest predictor of whether an individual was infected with a specific type of HPV was whether his or her partner had that type of the virus. The odds of infection with a given HPV type were dramatically higher among men and women whose partners had that type of infection than among those whose partners did not (odds ratios, 58.7 and 55.2, respectively). For men, each additional lifetime partner was associated with increased odds of HPV detection regardless of whether their partner had the HPV type being examined (1.04–1.05). For women, each additional partner was associated with increased odds of infection only if their partner was negative for the type of the virus under examination (1.09). Couple’s frequency of condom use was inversely associated with the odds of HPV for men but not for women, regardless of whether their partner tested positive for the HPV type being examined (0.6–0.9).
The HPV prevalence found in this study was very high—higher, in fact, than that found in previous studies not limited to individuals with new sex partners. The researchers suggest that the gender differences in the protective effects of condom use may indicate that male-to-female HPV transmission is more efficient than female-to-male transmission or that men benefit from more rapid HPV clearance. They conclude that their findings "underscore the very high sexual transmissibility of HPV infection and should assist policymakers in devising strategies to supplement the preventive effect of prophylactic HPV vaccination."
REFERENCE
1. Burchell AN et al., Influence of partner’s infection status on prevalent human papillomavirus among persons with a new sex partner, Sexually Transmitted Diseases, 2010, 37(1):34–40.