Abstract
Background. The association between partner human papillomavirus (HPV) viral load and incident HPV detection in heterosexual couples is unknown.
Methods. HPV genotypes were detected in 632 human immunodeficiency virus (HIV)–negative couples followed for 2 years in a male circumcision trial in Rakai, Uganda, using the Roche HPV Linear Array. This assay detects 37 genotypes and provides a semiquantitative measure of viral load based on the intensity (graded 1–4) of the genotype-specific band; a band intensity of 1 indicates a low genotype-specific HPV load, whereas an intensity of 4 indicates a high load. Using Poisson regression with generalized estimating equations, we measured the association between partner's genotype-specific viral load and detection of that genotype in the HPV-discordant partner 1 year later.
Results. Incident detection of HPV genotypes was 10.6% among men (54 of 508 genotype-specific visit intervals) and 9.0% among women (55 of 611 genotype-specific visit intervals). Use of male partners with a baseline genotype-specific band intensity of 1 as a reference yielded adjusted relative risks (aRRs) of 1.14 (95% confidence interval [CI], .58–2.27]) for incident detection of that genotype among women whose male partner had a baseline band intensity of 2, 1.75 (95% CI, .97–3.17) among those whose partner had an intensity of 3, and 2.52 (95% CI, 1.40–4.54) among those whose partner had an intensity of 4. Use of female partners with a baseline genotype-specific band intensity of 1 as a reference yielded an aRR of 2.83 (95% CI, 1.50–5.33) for incident detection of that genotype among men whose female partner had a baseline band intensity of 4. These associations were similar for high-risk and low-risk genotypes. Male circumcision also was associated with significant reductions in incident HPV detection in men (aRR, 0.53 [95% CI, .30–.95]) and women (aRR, 0.42 [95% CI, .23–.76]).
Conclusions. In heterosexual couples, the genotype-specific HPV load in one partner is associated with the risk of new detection of that genotype in the other partner. Interventions that reduce the HPV load may reduce the incidence of HPV transmission.
Keywords: human papillomavirus, viral load, transmission, male circumcision, HIV, Africa, Uganda, penile cancer, cervical cancer, sexually transmitted infections
Human papillomavirus (HPV) infection can cause genital warts, and high-risk HPV (HR-HPV) genotypes cause oral, anal, and penile cancer, as well as cervical cancer, the third most common cancer in women worldwide [1, 2]. Greater than 85% of the cervical cancer burden is in developing countries [2, 3]. HPV infection also may be associated with an increased risk of human immunodeficiency virus (HIV) acquisition in both men and women [4–7].
Models have shown that HPV transmissibility is substantially higher than that of other viral sexually transmitted pathogens [8, 9], but data on the natural history of HPV transmission between heterosexual partners are limited. Numerous studies throughout North America, Europe, and Asia have shown a concordance of HPV genotypes between heterosexual partners at a single time point [10, 11], and one study found an association between HPV load and concordance [12]. Another study evaluated the impact of HIV infection on HPV detection and clearance among men and women in South Africa [13]. However, data on transmission (or incident HPV detection, in couples) are primarily from studies in North America, with a limited number of heterosexual couples and limited information on risk behaviors [14–16].
Little is known about HPV transmission in heterosexual couples in African populations, which have among the highest rates of penile and cervical cancers worldwide [1, 2, 17]. While it has been shown that transmission of other viral sexually transmitted pathogens, such as HIV, are dependent on the source partner's viral load [18], no studies have evaluated the association between HPV load and incident HPV detection in partners. We hypothesized that a higher genotype-specific HPV load in HPV-infected men and women is positively associated with subsequent genotype-specific incident detection in their heterosexual partner. With the roll out of HPV vaccination and male circumcision programs in Africa, it is important to understand the risk factors and natural history of HPV infection among heterosexual couples in Africa. Here we report risk factors for incident HPV detection among heterosexual men and women in Rakai, Uganda.
MATERIALS AND METHODS
Study Population
HPV was evaluated among 1097 heterosexual couples, consisting of 1011 men and 1097 women aged 15–49 years, in Rakai District, Uganda. The number of women exceeded the number of men because of polygamy. Couples were assessed for HPV as part of a randomized trial of male circumcision for preventing transmission of HIV and other sexually transmitted pathogens in Rakai, enrolled between August 2003 and December 2006 [19–23]. Both partners reported being married or in long-term consensual relationships at baseline and were followed annually as a couple over 2 years. Men were randomly assigned to receive immediate circumcision (intervention) or circumcision delayed for 24 months (control). Written informed consent was provided by all male and female participants at enrollment. The consent form described study procedures, risks, benefits and the voluntary nature of participation.
Testing for HPV and HIV, physical examinations, and interviews to ascertain sociodemographic characteristics and sexual risk behaviors were conducted at baseline and at months 12 and 24 of follow-up. All subjects were offered free HIV counseling and testing, health education, and condoms at each visit.
This study was restricted to couples in which both partners were HIV negative at baseline. We also only included couples if HPV results were available for both partners at baseline and/or the month 12 visit and if HPV results were available 1 year later (ie, the month 12 or 24 visits) for either or both partners. We excluded visit intervals if either partner experienced HIV seroconversion during the interval or had indeterminate HIV test results at the end of an interval, because an association exists between HIV and HPV acquisition [24] and these events were too infrequent for stratified analyses.
The trials were approved by the HIV Subcommittee of the Ugandan National Council for Science and Technology (Kampala) and by 3 institutional review boards (IRBs): the Science and Ethics Committee of the Uganda Virus Research Institute (Entebbe, Uganda), the Johns Hopkins University Bloomberg School of Public Health IRB (Baltimore, Maryland), and the Western IRB (Olympia, Washington). The trials were overseen by independent data safety monitoring boards [20, 21] and were registered with clinicaltrials.gov (NCT00425984 and NCT00124878).
Laboratory Methods
Penile swab samples were obtained for HPV detection by trained clinicians, using a standardized procedure. Moistened polyethylene terephthalate–tipped swabs were rotated around the circumference of the penis at the coronal sulcus and placed in specimen-transport medium (Digene, Gaithersburg, Maryland). Female partners were asked to provide self-administered vaginal swabs for HPV detection [25]. Women were instructed to squat and then insert and rotate a 20-cm polyethylene terephthalate– or cotton-tipped swab high in the vaginal vault. After collection of the specimen, the women handed the swab to a field worker, who placed the swab in specimen transport medium (Digene). This approach to specimen collection was well accepted, with compliance rates of >90% [26]. Swabs were maintained at 4°C–10°C for <6 hours, when they were frozen at −80°C.
HPV genotyping was performed using the Roche HPV Linear Array, which detects 37 HR-HPV and low-risk HPV (LR-HPV) genotypes (Roche Diagnostics, Indianapolis, Indiana) [27]. HPV genotypes 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68 were considered to be HR-HPV genotypes. Swabs with no detectable cellular β-globin were excluded since the adequacy of the sample collection could not be ensured.
It has been previously demonstrated in both men and women that the linear array hybridization signal is linearly correlated with log-transformed HPV load (Spearman r = 0.73) [28–30]. A linear array band signal strength of 4 is approximately equivalent to a viral load of >2000 copies/5 µL. A band signal strength of 3 is approximately 200–2000 copies/5 µL. Linear array results and band intensity were evaluated independently by 2 observers, using a labeled acetate overlay provided by Roche, in which the overlay indicated the position of the genotype probes on the test strip. Observer disagreement was rare (1%–4% of results) and was resolved by reevaluation by the initial observers [29].
HIV status was determined using 2 separate enzyme-linked immunosorbent assays and confirmed by HIV type 1 Western blot, as previously described [20].
Statistical Analysis
The unit of observation was a genotype-specific HPV annual visit interval. The primary outcome was incident HPV detection after 12 and 24 months of follow-up in men and women who were in HPV genotype–discordant relationships at baseline or the month 12 visit. Incident HPV detection was defined as a newly detected HPV genotype in an individual who was negative for that genotype at the prior annual visit. Incident detection of HPV was assessed separately in men and women. Analyses were also stratified by HR-HPV and LR-HPV genotype status and trial arm.
The primary exposure was the genotype-specific HPV load in the partner at the prior visit and was evaluated as an ordinal variable consisting of 4 categories corresponding to the 4 linear array band intensities. A band intensity of 1 was the reference group. Associations between demographic and behavioral factors and partner HPV load were assessed using Poisson multivariate regression with generalized estimating equations and robust variance estimators. There were 9 instances in which a polygamous man was in an HPV genotype–discordant relationship with two or more female partners in this study. In these cases, the viral load for that genotype-specific HPV was considered as the highest viral load that the man was exposed to during the visit interval, such that a man who had 2 female partners, one with a band intensity equal to 3, and the other with band intensity equal to 1, was assumed to be exposed to a genotype-specific viral load of 3 at that visit. Sensitivity analyses were conducted after excluding these 9 observations.
Relative risks (RRs) and 95% confidence intervals (CIs) were estimated using modified Poisson regression with generalized estimating equations and robust variance estimators. Associations between HPV load and time-fixed covariates, including age and male circumcision status, and time-varying covariates, including HR-HPV and LR-HPV genotype status, detection of other HPV genotypes in the partner at the prior visit, nonmarital relationships, and condom use, were also assessed. Risk factors that were previously identified as potential confounders of the HPV load association in prior studies (eg, male circumcision status [21]) or that were associated with incident HPV detection with a P value of <.10 in univariate analysis were entered into a Poisson multivariate model to estimate adjusted RRs (aRRs) and 95% CIs of incident HPV detection.
Analyses were performed using Stata software (version 11; StataCorp, College Station, Texas) and R statistical software (version 3.2).
RESULTS
Study Population
There were 1097 couples assessed for HPV as part of the randomized trial of male circumcision. In this study, 356 couples (32%) were excluded because one or both partners were HIV infected at baseline. Of the 741 couples in which both partners were HIV negative at baseline, 10 were excluded because the man (7 individuals) or woman (3) underwent HIV seroconversion between baseline and the first annual visit. We also excluded 9 couples because either the man (1 individual) or woman (8) had an unknown HIV status after the baseline visit, owing to loss to follow-up or inconclusive results of HIV testing. Of the remaining 722 couples, 632 (88%) had the requisite HPV results available to assess HPV discordance at baseline or the month 12 visit and at the next annual visit by the man (438 couples [69%]) or woman (588 [3%]). These 632 couples consisted of 587 men and 632 women.
Table 1 shows baseline characteristics for the 632 HIV-negative couples assessed for HPV genotype discordance and incident HPV genotype detection. The median age of women was 25 years (interquartile range [IQR], 22–30 years), and the median age of men was 29 years (IQR, 25–34 years). Only 1 woman (0.2%) and 12 men (2%) reported consistent condom use. Approximately half the men (48% [284]) were in the intervention arm of the circumcision trial. Most couples (72% [456]) had detectable HPV infection in either the man (58% [365]) or woman (56% [356]) at their initial visit. In 31% of the couples (195), both partners had concordant positive test results for at least 1 HPV genotype, and in 28% (176) no HPV genotypes were detected in either partner. The number of genotypes detected in men with detectable HPV ranged from 1 to 12 (median, 2 genotypes; IQR, 1–3 genotypes), and the number of detectable genotypes in women ranged from 1 to 10 (median, 2 genotypes; IQR, 1–3 genotypes).
Table 1.
Baseline Characteristics of Individuals in 632 Couples Who Were Negative for Human Immunodeficiency Virus at Baseline and Assessed for Human Papillomavirus (HPV) Genotype Discordance and New HPV Genotype Detection in Rakai, Uganda
| Characteristic | Women (n = 632), | Men (n = 587), |
|---|---|---|
| No. (%) | No. (%) | |
| Age, y, median (IQR)a | 25 (22–30) | 29 (25–34) |
| Education | ||
| None | 92 (15) | 52 (9) |
| Primary | 454 (72) | 417 (71) |
| Secondary or more | 86 (14) | 118 (20) |
| Religion | ||
| Catholic | 374 (59) | 381 (65) |
| Protestant | 177 (28) | 163 (28) |
| Other | 81 (13) | 43 (7) |
| Self-reported consistent condom useb | 1 (0.2) | 12 (2) |
| Self-reported STI symptoms | ||
| Genital ulcer disease | 90 (14) | 46 (8) |
| Discharge | 297 (47) | 23 (4) |
| Dysuria | 128 (20) | 34 (6) |
| Intervention arm | ||
| Control | … | 303 (52) |
| Intervention | … | 284 (48) |
| Baseline HPV statusc | ||
| All HPV genotypes | ||
| Concordant negative | 176 (28) | … |
| Any female discordance | 258 (41) | … |
| Any male discordance | 252 (40) | … |
| Any positive concordance | 195 (31) | … |
| HR-HPV genotypes only | ||
| Concordant negative | 312 (49) | … |
| Any female discordance | 162 (26) | … |
| Any male discordance | 135 (21) | … |
| Any positive concordance | 96 (15) | … |
| LR-HPV genotypes only | ||
| Concordant negative | 272 (43) | … |
| Any female discordance | 186 (29) | … |
| Any male discordance | 184 (29) | … |
| Any positive concordance | 134 (21) | … |
The number of women exceeded the number of men because of polygamous couples.
Abbreviations: HR-HPV, high-risk HPV; IQR, interquartile range; LR-HPV, low-risk HPV; STI, sexually transmitted infection.
a The median difference in age between the male and female partner in the couple (calculated as male age minus female age) was 3 years (IQR, 1–6 years).
b Self-reported consistent condom use with all sex partners in the past year.
c HPV status of couple at first visit (enrollment or year 1) at which both partners in couple were assessed for HPV. Female discordance defined as couples in which an HPV genotype was detected in the woman and not the man (male discordance similarly defined).
Incident HPV Detection in Women
HPV infection was assessed at the baseline and month 12 visits in 588 couples with the requisite follow-up to assess incident HPV detection in female partners 1 year later. Among these 588 couples, we identified 270 in which 1 or more genotypes detected in the man (257 individuals) were not also detected in the female partner at the same visit. These couples contributed 611 genotype-specific observations, representing all 37 HPV genotypes assessed by the Roche Linear Array assay.
Of these 611 observations, genotypes in 39% (239) had a band intensity of 1, those in 25% (154) had a band intensity of 2, those in 19% (117) had a band intensity of 3, and those in 17% (101) had a band intensity of 4 (Table 2). Overall, genotypes in 9.0% of these observations (55) were detected in the female partner 1 year later. Genotypes with band intensity of 4, representing the highest viral load, were more than twice as likely to be detected in female partners at follow-up than were male HPV infections with the lowest band intensity (aRR, 2.52; 95% CI, 1.40–4.54). HPV genotypes with band intensities of 3 (aRR, 1.75; 95% CI, .97–3.17) and 2 (aRR, 1.14; 95% CI, .58–2.27) in males were also more frequently detected in their female partners at the next annual visit than were HPV genotypes with band intensity of 1. This increasing positive relationship between partner HPV load and incident HPV detection was statistically significant (P = .002, by the Cuzick test for trend).
Table 2.
Incident Detection of Genotype-Specific Human Papillomavirus (HPV) in Women, by Semiquantitative HPV Load in Their Male Partners at the Prior Visit and Other Risk Factors
| Variable | Newly Detected Genotypes/Genotype-specific Visit Intervals, Proportion (%)a | RR (95% CI) | P Value | aRR (95% CI) | P Value |
|---|---|---|---|---|---|
| Total | 55/611 (9.0) | … | … | ||
| Male partner HPV load, band intensityb | |||||
| 1 | 15/239 (6.3) | Reference | Reference | ||
| 2 | 10/154 (6.5) | 1.11 (.56–2.21) | .762 | 1.14 (.58–2.27) | .702 |
| 3 | 14/117 (12.0) | 1.78 (.99–3.21) | .054 | 1.75 (.97–3.17) | .065 |
| 4 | 16/101 (15.8) | 2.45 (1.36–4.40) | .003 | 2.52 (1.40–4.54) | .002 |
| High-risk HPV | |||||
| No | 32/395 (8.1) | Reference | … | ||
| Yes | 23/216 (10.7) | 1.36 (.90–2.07) | .145 | … | |
| Woman's agec | … | 1.00 (.97–1.04) | .890 | … | |
| Male partner's agec | … | 0.99 (.95–1.03) | .676 | … | |
| Male partner in intervention arm | |||||
| No | 40/330 (12.1) | Reference | Reference | ||
| Yes | 15/281 (5.3) | 0.43 (.24–.80) | .007 | 0.42 (.23–.76) | .004 |
| Woman reported GUD | |||||
| No | 41/501 (8.2) | Reference | … | ||
| Yes | 14/107 (13.1) | 1.59 (.79–3.20) | .194 | … | |
| Other HPV detected in woman | |||||
| No | 35/392 (8.9) | Reference | … | ||
| Yes | 20/219 (9.1) | 0.85 (.46–1.57) | .600 | … | |
| Other HPV detected in male partner | |||||
| No | 18/136 (13.2) | Reference | Reference | ||
| Yes | 37/475 (7.8) | 0.61 (.34–1.09) | .097 | 0.61 (.35–1.06) | .081 |
| Woman reported condom use | |||||
| None | 47/493 (9.5) | Reference | … | ||
| Inconsistent | 8/112 (7.1) | 0.73 (.30–1.80) | .499 | ||
| Consistent | 0/6 (0.0) | … | … | ||
| Woman reported sex with other partners | |||||
| No | 50/562 (8.9) | Reference | … | ||
| Yes | 5/49 (10.2) | 1.12 (.44–2.88) | .81 | … | |
Data are for 270 couples in which 1 or more genotypes detected in the man were not also detected in the female partner at the same visit.
Abbreviations: aRR, adjusted relative risk; CI, confidence interval; GUD, genital ulcer disease; RR, relative risk.
a Data are observations of a newly detected genotype in a woman during follow-up/detection of the same genotype in the male partner at baseline (%).
b As determined by linear array analysis. A band intensity of 1 indicates a low genotype-specific HPV load, whereas an intensity of 4 indicates a high load.
c Age was assessed as a continuous variable, in years.
Male partners' HPV genotypes were 58% less likely to be detected in women at follow-up if the man was in the intervention arm (immediate circumcision) of the male circumcision trial (aRR, 0.42; 95% CI, .23–.76; Table 2). There was no difference in the association between HPV load and incident HPV detection by trial arm (Supplementary Table 1). There also were no statistically significant associations between incident HPV detection in women and high-risk HPV status, genital ulcer disease in the woman, condom use, or sex with partners outside of the relationship. In a sensitivity analysis, a similar relationship between higher HPV load in male partners and incident HPV detection in women was observed when the analysis was stratified by HR-HPV or LR-HPV genotypes (Table 3).
Table 3.
Incident Detection of Genotype-Specific Human Papillomavirus (HPV) in Women, by Semiquantitative Load and Oncogenic Risk of HPV Genotypes in Their Male Partners at the Prior Visit
| HPV Load, Band Intensitya | High-Risk HPV |
Low-Risk HPV |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Newly Detected Genotypes/Genotype-specific Visit Intervals, Proportion (%)b | RR (95% CI) | P Value | aRR (95% CI) | P Value | Newly Detected Genotypes/Genotype-specific Visit Intervals, Proportion (%)b | RR (95% CI) | P Value | aRR (95% CI) | P Value | |
| 1 | 4/79 (5.1) | Reference | Reference | 11/160 (6.9) | Reference | Reference | ||||
| 2 | 5/49 (10.2) | 2.05 (.61–6.96) | .247 | 2.00 (.60–6.74) | .259 | 5/105 (4.8) | 0.76 (.31–1.85) | .548 | 0.83 (.35–1.95) | .663 |
| 3 | 6/46 (13.0) | 2.57 (.85–7.82) | .095 | 2.41 (.81–7.14) | .113 | 8/71 (11.3) | 1.57 (.70–3.53) | .274 | 1.62 (.71–3.66) | .250 |
| 4 | 8/42 (19.1) | 3.84 (1.29–11.5) | .016 | 4.32 (1.47–12.71) | .008 | 8/59 (13.6) | 1.97 (.85–4.60) | .114 | 1.97 (.86–4.48) | .108 |
Abbreviations: aRR, adjusted relative risk; CI, confidence interval; RR, relative risk.
a As determined by linear array analysis. A band intensity of 1 indicates a low genotype-specific HPV load, whereas an intensity of 4 indicates a high load.
b Data are observations of a newly detected genotype in a woman during follow-up/detection of the same genotype in the male partner at baseline (%).
Incident HPV Detection in Men
HPV infection was assessed at baseline and month 12 visits in 438 couples with the requisite follow-up to assess incident HPV detection in male partners 1 year later. Among these 438 couples, we identified 194 in which 1 or more genotypes detected in the woman were not also detected in the male partner at the same visit. Only 6 of these men had 2 female partners who had detectable infection with the same HPV genotype (9 observations). Overall, these couples contributed 508 observations, representing 36 of 37 HPV genotypes assessed by the Roche HPV Linear Array assay.
Of these 508 observations in female partners, genotypes in 31% (157) had a band intensity of 1, those in 17% (86) had band intensity of 2, those in 22% (112) had band intensity of 3, and those in 30% (153) had band intensity of 4 (Table 4). Incident HPV genotype detection in men was similar to that in women: genotypes in 10.6% of observations (54 of 508) were detected in men 1 year later. Genotypes with a band intensity of 4 in female partners were associated with an aRR of male HPV detection at follow-up of 2.83 (95% CI, 1.50–5.33), compared with genotypes with the lowest band intensity. This association did not differ substantially by HR-HPV or LR-HPV status (Table 5) or if men who had >1 partner with detectable infection with the same genotype were excluded from the analysis. Female genotypes with band intensities of 2 or 3 were not associated with incident HPV detection in men.
Table 4.
Incident Detection of Genotype-Specific Human Papillomavirus (HPV) in Men, by Semiquantitative HPV Load in Their Female Partners at the Prior Visit and Other Risk Factors
| Variable | Newly Detected Genotypes/Genotype-specific Visit Intervals, Proportion (%)a |
RR (95% CI) | P Value | aRR (95% CI) | P Value |
|---|---|---|---|---|---|
| Total | 54/508 (10.6) | ||||
| Female partner HPV load, band intensityb | |||||
| 1 | 10/157 (6.4) | Reference | Reference | ||
| 2 | 9/86 (10.5) | 1.67 (.75–3.67) | .209 | 1.70 (.77–3.75) | .186 |
| 3 | 8/112 (7.1) | 1.12 (.46–2.75) | .797 | 1.07 (.43–2.66) | .891 |
| 4 | 27/153 (17.7) | 2.78 (1.48–5.24) | .002 | 2.83 (1.50–5.33) | .001 |
| High-risk HPV | |||||
| No | 29/263 (11.0) | Reference | … | ||
| Yes | 25/245 (10.2) | 0.91 (.54–1.54) | .735 | … | |
| Man's agec | … | 1.01 (.97–1.05) | .615 | … | |
| Female partner's agec | … | 0.98 (.94–1.02) | .338 | … | |
| Man in intervention arm | |||||
| No | 37/293 (12.6) | Reference | Reference | ||
| Yes | 17/215 (7.9) | 0.58 (.32–1.05) | .073 | 0.53 (.30–.95) | .033 |
| Man reported GUD | |||||
| No | 46/459 (10.0) | Reference | … | ||
| Yes | 8/49 (16.3) | 1.55 (.75–3.20) | .233 | … | |
| Other HPV detected in man | |||||
| No | 34/337 (10.1) | Reference | … | ||
| Yes | 20/171 (11.7) | 1.09 (.61–1.92) | .778 | … | |
| Other HPV detected in female partner | |||||
| No | 13/86 (15.1) | Reference | Reference | ||
| Yes | 41/422 (9.7) | 0.65 (.36–1.2) | .162 | 0.62 (.35–1.12) | .111 |
| Man reported condom use | |||||
| None | 37/306 (12.1) | Reference | … | ||
| Inconsistent | 17/202 (8.4) | 0.70 (.40–1.23) | .212 | ||
| Consistent | 0/3 (0.0) | … | … | ||
| Man reported sex with other partners | |||||
| No | 22/251 (8.8) | Reference | … | ||
| Yes | 32/257 (12.5) | 1.45 (.86–2.45) | .162 | … | |
Data are for 194 couples in which 1 or more genotypes detected in the woman were not also detected in the male partner at the same visit.
Abbreviations: aRR, adjusted relative risk; CI, confidence interval; GUD, genital ulcer disease; RR, relative risk.
a Data are observations of a newly detected genotype in a man during follow-up/detection of the same genotype in the female partner at baseline (%).
b As determined by linear array analysis. A band intensity of 1 indicates a low genotype-specific HPV load, whereas an intensity of 4 indicates a high load.
c Age was assessed as a continuous variable, in years.
Table 5.
Incident Detection of Genotype Specific Human Papillomavirus (HPV) in Men, by Semiquantitative Viral Load and Oncogenic Risk of HPV Genotypes in Their Female Partners at the Prior Visit
| HPV Load, Band Intensitya | High-Risk HPV |
Low-Risk HPV |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Newly Detected Genotypes/Genotype-specific Visit Intervals, Proportion (%)b | RR (95% CI) | P Value | aRR (95% CI) | P Value | Newly Detected Genotypes/Genotype-specific Visit Intervals, Proportion (%)b | RR (95% CI) | P Value | aRR (95% CI) | P Value | |
| 1 | 4/83 (4.8) | Reference | Reference | 6/74 (8.1) | Reference | Reference | ||||
| 2 | 6/43 (14.0) | 2.93 (1.06–8.11) | .038 | 2.73 (.96–7.81) | .060 | 3/43 (7.0) | 0.78 (.22–2.74) | .702 | 0.80 (.23–2.79) | .722 |
| 3 | 4/52 (7.7) | 1.58 (.44–5.65) | .485 | 1.55 (.42–5.71) | .507 | 4/60 (6.7) | 0.92 (.30–2.83) | .890 | 0.89 (.28–2.87) | .856 |
| 4 | 11/67 (16.4) | 3.33 (1.21–9.12) | .019 | 3.76 (1.36–10.37) | .011 | 16/86 (18.6) | 2.35 (1.05–5.23) | .037 | 2.34 (1.06–5.22) | .036 |
Abbreviations: aRR, adjusted relative risk; CI, confidence interval; RR, relative risk.
a As determined by linear array analysis. A band intensity of 1 indicates a low genotype-specific HPV load, whereas an intensity of 4 indicates a high load.
b Data are observations of a newly detected genotype in a man during follow-up/detection of the same genotype in the female partner at baseline (%).
The HPV infections observed in women were 48% less likely to be detected in men at follow-up if they were in the intervention arm of the circumcision trial (aRR, 0.53; 95% CI, .30–.95; Table 4). Similar to women, we also observed no difference in the association between HPV load and incident HPV detection in men when stratified by trial arm (Supplementary Table 1). Incident HPV detection in men also was not statistically significantly associated with HR-HPV status, genital ulcer disease in the man, inconsistent condom use, or sex with partners outside of the relationship (Table 4).
HPV Load and Persistence
Higher HPV load in male partners was also associated with persistent HPV detection in these men at follow-up. Among male partners who had HPV results 1 year later (83% [216 of 529]), the rates of persistence were 28% (25 of 91; RR, 2.00; 95% CI, 1.11–3.60) for HPV genotypes with a band intensity of 4, 20% (20 of 96; RR, 1.65; 95% CI, 1.06–2.59) with a band intensity of 3, and 13% (17 of 135; RR, 1.12; 95% CI, .67–1.89) with a band intensity of 2, compared with 9% (19 of 207) for genotypes with a band intensity of 1.
HPV load in females was associated with an increased frequency of persistent HPV detection in these women at follow-up. After exclusion of 6 polygamous men, 98% of female partners (185 of 188) had HPV results available 1 year later for assessment of persistent infection. At follow-up, the rates of persistent detection in women were 57% (82 of 145; RR, 2.86; 95% CI, 2.02–4.07) for HPV genotypes with a band intensity of 4, 55% (48 of 108; RR, 2.18; 95% CI, 1.50–3.18) for those with a band intensity of 3, and 33% (27 of 83; RR, 1.75; 95% CI, 1.14–2.69) for those with band intensity of 2, compared with 18% (19 of 207) for genotypes with band intensity of 1.
The risk of HPV persistence was significantly less in circumcised men relative to that in men in the control arm (RR, 0.39; 95% CI, 0.20–0.73); however, male circumcision status did not impact HPV persistence in women (RR, 0.84; 95% CI, .63–1.11). High-risk HPV genotypes were no more likely to persist than LR-HPV genotypes in men (RR, 0.74; 95% CI, .48–1.14) or women (RR, 0.95; 95% CI, .74–1.20).
DISCUSSION
Among couples initially discordant for 1 or more HPV genotypes, we found that a high HPV load, as measured by linear array band intensity, was associated with an increased risk of new detection of the specific genotype(s) in both male and female heterosexual partners 1 year later. The association between HPV load in partners and incident HPV detection may be mediated by a higher infectious dose at the time of transmission; longer exposure to HPV, owing to an increased frequency of HPV persistence in partners with high viral load; or some combination of these mechanisms. Indeed, previous studies found that a higher viral load was associated with HPV persistence [31, 32]. It is also plausible that higher-level HPV genotypes represent more-recent infection, in which case incident detections of HPV genotypes in partners more likely represent first-time infections that have not been immunologically controlled.
The rate of new HPV detection among men and women was almost identical. While one study reported similar detection rates between men and women in heterosexual couples [16], other studies have found that female-to-male transmission may be 2-fold higher [13–15, 33]. Detection rates can vary by follow-up interval, specimen collection method, coital frequency, autoinoculation rates, contaminating DNA from recent sexual intercourse, participant age, and partnership length [13–16, 33]. Although we found no significant differences in HPV detection by gender in this study, it is possible that men or women may be at higher risk for infection, owing to sampling limitations.
A high HPV load has been associated with increased morbidity. Among both men and women, higher viral load has been associated with persistence of HR-HPV [31, 34], which was also observed in this study. Higher viral load among men is associated with detection of HR-HPV at multiple penile sites [35] and with flat penile lesions [36]. In addition, higher viral load in women has been associated with the incidence of cervical lesions [37–39]. Combined with the current study's findings that HR-HPV load correlates with newly detected HPV in heterosexual partners, interventions that reduce the HPV load may have public health benefit.
Potential interventions, such as a therapeutic HPV vaccine or medical male circumcision, may avert new HPV infections. While prophylactic HPV vaccines do not have substantial impact on established infection, peptide-based therapeutic HPV vaccines have been designed to treat these individuals [40, 41]. These vaccines appear to have cross-protection against nonvaccine genotypes. If these vaccines could also be successful in lowering the HPV load, they may also assist in lowering transmission. In addition, since male circumcision decreases the HR-HPV load among men and their female partners [28, 29], the procedure may reduce HR-HPV transmission within couples. The extent to which a population-level reduction in HPV load would reduce overall HPV transmission and HPV-associated diseases should be evaluated in future studies.
Previous studies found that male circumcision in HIV-negative men decreased the incidence of HR-HPV detection by approximately 33% in men and by 23% in their female partners [19, 21, 42–46]. The increased efficacy rates in this study of male circumcision to protect both men (47%) and women (58%) are likely more accurate than our previous randomized trial findings since this study only evaluated HPV-discordant couples and did not include concordant HPV-negative couples, which would reduce observed efficacy.
There are limitations with this study. The interpretation of HPV epidemiology is difficult, particularly when the interval between sample collections is long. This may have led to underestimation of the number of new detections, since individuals may have both acquired and cleared HPV genotypes between visits. Second, noninvasive methods of HPV detection have been historically difficult, owing to inadequate cell recovery [47, 48]. Consequently, we may also have misclassified persistent infection as new events if we did not detect HPV infection at the previous study visit. Moreover, we have previously demonstrated that β-globin detection is significantly lower among circumcised men, compared with uncircumcised men [21], which could also affect our classification of discordant relationships or new HPV detection. However, we were conservative in our estimates of new detection, which were restricted to sequential samples with amplifiable cellular or viral DNA to ensure the adequacy of sample collection. In addition, the hybridization signal strength is based on intensity relative to that of a high and low β-globin control, which provides some level of internal sampling and amplification efficiency control. Third, newly detected virus may also reflect reactivation of latent HPV infection after a loss of local immune response to viral infection, which is likely more common with increasing age [49, 50]. Last, we assessed penile HPV at the coronal sulcus only, not at other genital sites. However, our results were robust to adjustment for behavioral and clinical variables that may have confounded the association between viral load and new detection among heterosexual partners, including male circumcision status.
In conclusion, we found that a partner's HPV load is associated with new detection of HPV infections in heterosexual couples. Our findings highlight the potential role of viral load in the natural history of HPV transmission and the potential public health benefit of interventions, such as male circumcision, that reduce HPV load.
Supplementary Data
Supplementary materials are available at http://jid.oxfordjournals.org. Consisting of data provided by the author to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the author, so questions or comments should be addressed to the author.
Notes
Acknowledgments. We thank the study participants and the Rakai Community Advisory Board, whose commitment and cooperation made this study possible.
Disclaimer. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Financial support. This work was supported by the National Institutes of Health (NIH; grants U1AI51171, 1K23AI093152-01A1 [to A. A. R. T.], and T32AI102 [to M. K. G.]); the Bill and Melinda Gates Foundation (grant 22006.02); the National Institute of Allergy and Infectious Diseases (NIAID), NIH (grants 1K23AI093152-01A1, U01-AI-068613, and 3U01-AI075115-03S1); the Division of Intramural Research, NIAID, NIH; and the Doris Duke Charitable Foundation (clinician scientist development awards to A. A. R. T. [no. 22006.02] and M. K. G.).
Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
References
- 1.de Sanjose S, Diaz M, Castellsague X et al. Worldwide prevalence and genotype distribution of cervical human papillomavirus DNA in women with normal cytology: a meta-analysis. Lancet Infect Dis 2007; 7:453–9. [DOI] [PubMed] [Google Scholar]
- 2.Ferlay J, Shin HR, Bray F, Forman D, Mathers C, Parkin DM. Estimates of worldwide burden of cancer in 2008: GLOBOCAN 2008. Int J Cancer 2010; 127:2893–917. [DOI] [PubMed] [Google Scholar]
- 3.Sahasrabuddhe VV, Parham GP, Mwanahamuntu MH, Vermund SH. Cervical cancer prevention in low- and middle-income countries: feasible, affordable, essential. Cancer Prev Res 2012; 5:11–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Averbach SH, Gravitt PE, Nowak RG et al. The association between cervical HPV infection and HIV acquisition among women in Zimbabwe. AIDS 2010; 24:1035–42. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Smith-McCune KK, Shiboski S, Chirenje MZ et al. Type-specific cervico-vaginal human papillomavirus infection increases risk of HIV acquisition independent of other sexually transmitted infections. PLoS One 2010; 5:e10094. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Tobian AA, Grabowski MK, Kigozi G et al. Human papillomavirus clearance among males is associated with HIV acquisition and increased dendritic cell density in the foreskin. J Infect Dis 2013; 207:1713–22. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Auvert B, Lissouba P, Cutler E, Zarca K, Puren A, Taljaard D. Association of oncogenic and nononcogenic human papillomavirus with HIV incidence. J Acquir Immune Defic Syndr 2010; 53:111–6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Burchell AN, Richardson H, Mahmud SM et al. Modeling the sexual transmissibility of human papillomavirus infection using stochastic computer simulation and empirical data from a cohort study of young women in Montreal, Canada. Am J Epidemiol 2006; 163:534–43. [DOI] [PubMed] [Google Scholar]
- 9.Bogaards JA, Xiridou M, Coupe VM, Meijer CJ, Wallinga J, Berkhof J. Model-based estimation of viral transmissibility and infection-induced resistance from the age-dependent prevalence of infection for 14 high-risk types of human papillomavirus. Am J Epidemiol 2010; 171:817–25. [DOI] [PubMed] [Google Scholar]
- 10.Reiter PL, Pendergraft WF III, Brewer NT. Meta-analysis of human papillomavirus infection concordance. Cancer Epidemiol Biomarkers Prev 2010; 19:2916–31. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Nyitray AG, Menezes L, Lu B et al. Genital human papillomavirus (HPV) concordance in heterosexual couples. J Infect Dis 2012; 206:202–11. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Bleeker MC, Hogewoning CJ, Berkhof J et al. Concordance of specific human papillomavirus types in sex partners is more prevalent than would be expected by chance and is associated with increased viral loads. Clin Infect Dis 2005; 41:612–20. [DOI] [PubMed] [Google Scholar]
- 13.Mbulawa ZZ, Marais DJ, Johnson LF, Coetzee D, Williamson AL. Impact of human immunodeficiency virus on the natural history of human papillomavirus genital infection in South African men and women. J Infect Dis 2012; 206:15–27. [DOI] [PubMed] [Google Scholar]
- 14.Widdice L, Ma Y, Jonte J et al. Concordance and transmission of human papillomavirus within heterosexual couples observed over short intervals. J Infect Dis 2013; 207:1286–94. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Hernandez BY, Wilkens LR, Zhu X et al. Transmission of human papillomavirus in heterosexual couples. Emerg Infect Dis 2008; 14:888–94. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Burchell AN, Coutlee F, Tellier PP, Hanley J, Franco EL. Genital transmission of human papillomavirus in recently formed heterosexual couples. J Infect Dis 2011; 204:1723–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Tobian AA, Gray RH. Male foreskin and oncogenic human papillomavirus infection in men and their female partners. Future Microbiol 2011; 6:739–45. [DOI] [PubMed] [Google Scholar]
- 18.Quinn TC, Wawer MJ, Sewankambo N et al. Viral load and heterosexual transmission of human immunodeficiency virus type 1. Rakai Project Study Group. N Engl J Med 2000; 342:921–9. [DOI] [PubMed] [Google Scholar]
- 19.Wawer MJ, Tobian AA, Kigozi G et al. Effect of circumcision of HIV-negative men on transmission of human papillomavirus to HIV-negative women: a randomised trial in Rakai, Uganda. Lancet 2011; 277:209–18. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Gray RH, Kigozi G, Serwadda D et al. Male circumcision for HIV prevention in men in Rakai, Uganda: a randomised trial. Lancet 2007; 369:657–66. [DOI] [PubMed] [Google Scholar]
- 21.Tobian AA, Serwadda D, Quinn TC et al. Male circumcision for the prevention of HSV-2 and HPV infections and syphilis. N Engl J Med 2009; 360:1298–309. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Tobian AA, Ssempijja V, Kigozi G et al. Incident HIV and herpes simplex virus type 2 infection among men in Rakai, Uganda. AIDS 2009; 23:1589–94. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Wawer MJ, Makumbi F, Kigozi G et al. Circumcision in HIV-infected men and its effect on HIV transmission to female partners in Rakai, Uganda: a randomised controlled trial. Lancet 2009; 374:229–37. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Nowak RG, Gravitt P, Morrison CS et al. Increases in human papillomavirus (HPV) detection during early HIV infection among women in Zimbabwe. J Infect Dis 2011; 203:1182–91. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Serwadda D, Wawer MJ, Shah KV et al. Use of a hybrid capture assay of self-collected vaginal swabs in rural Uganda for detection of human papillomavirus. J Infect Dis 1999; 180:1316–9. [DOI] [PubMed] [Google Scholar]
- 26.Ogilvie GS, Patrick DM, Schulzer M et al. Diagnostic accuracy of self collected vaginal specimens for human papillomavirus compared to clinician collected human papillomavirus specimens: a meta-analysis. Sex Transm Infect 2005; 81:207–12. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Gravitt PE, Peyton CL, Apple RJ, Wheeler CM. Genotyping of 27 human papillomavirus types by using L1 consensus PCR products by a single-hybridization, reverse line blot detection method. J Clin Microbiol 1998; 36:3020–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Davis MA, Gray RH, Grabowski MK et al. Male circumcision decreases high-risk human papillomavirus viral load in female partners: a randomized trial in Rakai, Uganda. Int J Cancer 2013; 133:1247–52. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Wilson LE, Gravitt P, Tobian AA et al. Male circumcision reduces penile high-risk human papillomavirus viral load in a randomised clinical trial in Rakai, Uganda. Sex Transm Infect 2013; 89:262–6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Wentzensen N, Gravitt PE, Long R et al. Human papillomavirus load measured by linear array correlates with quantitative PCR in cervical cytology specimens. J Clin Microbiol 2012; 50:1564–70. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Grabowski MK, Gray RH, Serwadda D et al. High-risk human papillomavirus viral load and persistence among heterosexual HIV-negative and HIV-positive men. Sex Transm Infect 2014; 90:337–43. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Beachler DC, Guo Y, Xiao W et al. High oral human papillomavirus type 16 load predicts long-term persistence in individuals with or at risk for HIV infection. J Infect Dis 2015; 212:1588–91. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Mbulawa ZZ, Johnson LF, Marais DJ, Coetzee D, Williamson AL. The impact of human immunodeficiency virus on human papillomavirus transmission in heterosexually active couples. J Infect 2013; 67:51–8. [DOI] [PubMed] [Google Scholar]
- 34.Xi LF, Hughes JP, Castle PE et al. Viral load in the natural history of human papillomavirus type 16 infection: a nested case-control study. J Infect Dis 2011; 203:1425–33. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Flores R, Lu B, Nielson C et al. Correlates of human papillomavirus viral load with infection site in asymptomatic men. Cancer Epidemiol Biomarkers Prev 2008; 17:3573–6. [DOI] [PubMed] [Google Scholar]
- 36.Bleeker MC, Hogewoning CJ, Voorhorst FJ et al. HPV-associated flat penile lesions in men of a non-STD hospital population: less frequent and smaller in size than in male sexual partners of women with CIN. Int J Cancer 2005; 113:36–41. [DOI] [PubMed] [Google Scholar]
- 37.Dalstein V, Riethmuller D, Pretet JL et al. Persistence and load of high-risk HPV are predictors for development of high-grade cervical lesions: a longitudinal French cohort study. Int J Cancer 2003; 106:396–403. [DOI] [PubMed] [Google Scholar]
- 38.Gravitt PE, Kovacic MB, Herrero R et al. High load for most high risk human papillomavirus genotypes is associated with prevalent cervical cancer precursors but only HPV16 load predicts the development of incident disease. Int J Cancer 2007; 121:2787–93. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.Xi LF, Kiviat NB, Galloway DA, Zhou XH, Ho J, Koutsky LA. Effect of cervical cytologic status on the association between human papillomavirus type 16 DNA load and the risk of cervical intraepithelial neoplasia grade 3. J Infect Dis 2008; 198:324–31. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 40.Nakagawa M, Greenfield W, Moerman-Herzog A, Coleman HN. Cross-reactivity, epitope spreading, and de novo immune stimulation are possible mechanisms of cross-protection of nonvaccine human papillomavirus (HPV) types in recipients of HPV therapeutic vaccines. Clin Vaccine Immunol 2015; 22:679–87. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 41.Liu TY, Hussein WM, Toth I, Skwarczynski M. Advances in peptide-based human papillomavirus therapeutic vaccines. Curr Top Med Chem 2012; 12:1581–92. [DOI] [PubMed] [Google Scholar]
- 42.Gray RH, Serwadda D, Kong X et al. Male circumcision decreases acquisition and increases clearance of high-risk human papillomavirus in HIV-negative men: a randomized trial in Rakai, Uganda. J Infect Dis 2010; 201:1455–62. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 43.Tobian AA, Gray RH. The medical benefits of male circumcision. JAMA 2011; 306:1479–80. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 44.Auvert B, Sobngwi-Tambekou J, Cutler E et al. Effect of male circumcision on the prevalence of high-risk human papillomavirus in young men: results of a randomized controlled trial conducted in orange farm, South Africa. J Infect Dis 2009; 199:14–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 45.Smith J, Backes DM, Bailey R et al. The effect of male circumcision on incident and persistent penile HPV infections in men from Kenya. Presented at: 26th International Papillomavirus Conference, Montreal, Canada, 3–8 July 2010. [Google Scholar]
- 46.Tobian AA, Kong X, Gravitt PE et al. Male circumcision and anatomic sites of penile high-risk human papillomavirus in Rakai, Uganda. Int J Cancer 2011; 129:2970–5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 47.Vermund SH, Schiffman MH, Goldberg GL, Ritter DB, Weltman A, Burk RD. Molecular diagnosis of genital human papillomavirus infection: comparison of two methods used to collect exfoliated cervical cells. Am J Obstet Gynecol 1989; 160:304–8. [DOI] [PubMed] [Google Scholar]
- 48.Goldberg GL, Vermund SH, Schiffman MH, Ritter DB, Spitzer C, Burk RD. Comparison of Cytobrush and cervicovaginal lavage sampling methods for the detection of genital human papillomavirus. Am J Obstet Gynecol 1989; 161:1669–72. [DOI] [PubMed] [Google Scholar]
- 49.Gravitt PE. The known unknowns of HPV natural history. J Clin Invest 2011; 121:4593–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 50.Gravitt PE, Rositch AF, Silver MI et al. A cohort effect of the sexual revolution may be masking an increase in human papillomavirus detection at menopause in the United States. J Infect Dis 2013; 207:272–80. [DOI] [PMC free article] [PubMed] [Google Scholar]
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