Effect of HSV-2 Serostatus on Acquisition of HIV by Young Men: Results of a Longitudinal Study in Orange Farm, South Africa

Journal of Infectious Diseases, Apr 2009

BackgroundThe objectives of this study were to assess the impact among young men of herpes simplex virus type 2 (HSV-2) status on the acquisition of human immunodeficiency virus (HIV) and on the protective effect of male circumcision against HIV acquisition MethodsWe used data collected during a male circumcision trial conducted in Orange Farm, South Africa. We estimated adjusted incidence rate ratios (IRRs) for HIV acquisition, using survival analysis and background characteristics, HSV-2 status, male circumcision status, and sexual behavior as covariates ResultsCompared with subjects who remained HSV-2 negative throughout the study, subjects who were HSV-2 positive at enrollment had an adjusted IRR of 3.3 (95% confidence interval [CI], 1.5–7.4; P=.004), and those who became HSV-2 positive during follow-up had an adjusted IRR of 7.0 (95% CI, 3.9–12.4; P<.001). The population fraction of incident HIV infection attributable to HSV-2 was 27.8% (95% CI, 17.7%–37.2%). Intention-to-treat analysis of the protective effect of male circumcision on HIV acquisition was the same among men with and men without HSV-2 (0.38 vs. 0.37; P=.93) ConclusionsThis study shows that HSV-2 has a substantial impact on HIV acquisition among young South African men. It suggests that HSV-2 infection enhances HIV acquisition and is responsible for ∼25% of incident cases of HIV infection. However, the protective effect of male circumcision against HIV acquisition appears independent of HSV-2 serostatus Trial registrationClinicalTrials.gov identifier: NCT00122525

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Effect of HSV-2 Serostatus on Acquisition of HIV by Young Men: Results of a Longitudinal Study in Orange Farm, South Africa

Joelle Sobngwi-Tambekou 2 3 Dirk Taljaard 2 Pascale Lissouba 2 3 Kevin Zarca 2 3 Adrian Puren 2 4 Emmanuel Lagarde 1 2 Bertran Auvert () 0 2 3 5 0 Assistance Publique-Hpitaux de Paris, Boulogne 1 INSERM U593, Bordeaux 2 Received 28 June 2008; accepted 22 October 2008; electronically published 16 February 2009. Potential conflicts of interest: none reported. Presented in part: 16th Biennial Meeting of the International Society for Sexually Transmitted Diseases Research , Amsterdam, the Netherlands , 10 -13 July 2005 (abstract TO-704). Financial support: ANRS (grant 1265); NICD; Gates Foundation (grant 33759) ; INSERM; SACEMA. Author contributions: J.S.-T. and B.A. analyzed the data and wrote the first draft; D.T. organized the collection of the samples; A.P. analyzed the samples; P.L., K.Z., and E.L. contributed to the writing. Paul Vaillant-Couturier, 94804 Villejuif, France 3 INSERM U687, Villejuif 4 National Institute for Communicable Diseases , Johannesburg, South Africa 5 University of Versailles , Versailles, France (See the editorial commentary by Bailey and Mehta, on pages 923-5.) Background. The objectives of this study were to assess the impact among young men of herpes simplex virus type 2 (HSV-2) status on the acquisition of human immunodeficiency virus (HIV) and on the protective effect of male circumcision against HIV acquisition. Methods. We used data collected during a male circumcision trial conducted in Orange Farm, South Africa. We estimated adjusted incidence rate ratios (IRRs) for HIV acquisition, using survival analysis and background characteristics, HSV-2 status, male circumcision status, and sexual behavior as covariates. Results. Compared with subjects who remained HSV-2 negative throughout the study, subjects who were HSV-2 positive at enrollment had an adjusted IRR of 3.3 (95% confidence interval [CI], 1.5-7.4; P .004), and those who became HSV-2 positive during follow-up had an adjusted IRR of 7.0 (95% CI, 3.9 -12.4; P .001). The population fraction of incident HIV infection attributable to HSV-2 was 27.8% (95% CI, 17.7%-37.2%). Intention-to-treat analysis of the protective effect of male circumcision on HIV acquisition was the same among men with and men without HSV-2 (0.38 vs. 0.37; P .93). Conclusions. This study shows that HSV-2 has a substantial impact on HIV acquisition among young South African men. It suggests that HSV-2 infection enhances HIV acquisition and is responsible for 25% of incident cases of HIV infection. However, the protective effect of male circumcision against HIV acquisition appears independent of HSV-2 serostatus. Trial registration. ClinicalTrials.gov identifier: NCT00122525. - sition 2 4-fold [210] and increases the risk of HIV-1 transmission [2, 1114]. A recent meta-analysis found that, in fixed-effects analyses, the presence of HSV-2 shedding significantly affected HIV shedding in genital tract specimens (OR, 1.5; 95% CI, 1.0 2.1) [15]. HIV, in turn, increases the risk of HSV-2 transmission [2]. There is a direct relationship between CD4 cell count and the rate of HSV-2 reactivation. Outbreaks of HSV-2 infection are more severe, extensive, persistent, and invasive for those with advanced HIV disease [14, 16]. Persistent HSV-2 infection was one of the original opportunistic infections that resulted in the identification of AIDS [17]. Three randomized controlled trials have demonstrated that male circumcision reduces the risk of female-to-male sexual transmission of HIV by 60% [18 20]. A meta-analysis of observational data showed that male circumcision was associated with a borderline statistically significant reduction in the risk of HSV-2 infection (summary relative risk, 0.88; 95% CI, 0.771.01]) [21]. The main objectives of this study were to estimate the effect of HSV-2 status on HIV incidence among young males, the population fraction of HIV infections attributable to HSV-2 infection, and the effect of HSV-2 status on the protective effect of male circumcision against HIV acquisition by men. The secondary objective was to study the risk factors of HSV-2 incidence, especially the effect of male circumcision. For these analyses, we used data collected during a randomized controlled trial on male circumcision in Orange Farm, South Africa, which demonstrated that male circumcision reduced the risk of HIV acquisition [18]. SUBJECTS, MATERIALS, AND METHODS Collection of data. Because the technical details, participants, and HIV testing methods for the trial (French National Agency for AIDS Research [ANRS] study 1265) have been described elsewhere [18], only a summary will be presented here. Between February 2002 and July 2004, 3274 uncircumcised men aged 18 24 years were recruited, randomized into 2 groups, and followed up. Recruitment was conducted independently of HIV and HSV-2 status. Male circumcision was offered to the intervention group immediately after randomization and to the control group after the end of the follow-up period. During follow-up visits at 3 months (M3), 12 months (M12), and 21 months (M21), circumcision status was ascertained by a nurse by genital examination, and a blood sample was obtained. In addition, information about sexual behavior was collected, including the number of spousal and non-spousal sex partners as a function of time and the history of condom use with each of these partners. The lifetime number of spousal and nonspousal sex partners was used for baseline description. For multivariate analyses, we used the number of nonspousal sex partners in the past 3 months at M3 and in the past 9 months at M12 and M21. The data set used in this study included information from 590 additional M21 visits (20.0% of the total number of M21 visits). These data were not included in the earlier report of the randomized trial on male circumcision [18] because corresponding biological data were not available at that time. Laboratory methods. Plasma specimens were extracted from each blood sample immediately after collection and were stored at 20C until processing. They were tested using an HSV-2specific IgG assay (Kalon HSV-2 gG2 assay [Kalon Biologicals]) to detect HSV-2 antibodies, with an index cutoff value of 1.1, according to the manufacturers recommendations. Data analysis. HIV status, treated as a censored datum with time being continuous, was established at each follow-up visit for periods of nonuniform duration. These data were modeled using a piecewise exponential proportional hazards model in which the baseline hazard was considered constant between consecutive follow-up visits. This theoretical model was established to take into account the precise duration between each visit as well as the time-dependent covariates. It was implemented by running a Poisson log-linear model on a data set with each line corresponding to 1 of 3 periods of follow-up: from randomization (M1) to M3, M3M12, and M12M21. During these periods, participants remained HIV negative or became HIV positive [2224]. HIV incidence rates and incidence rate ratios (IRRs) were estimated for the intervention and control groups (intention-to-treat [ITT] analysis) and for circumcised and uncircumcised men (as-treated [AT] analysis). Adjusted IRRs were obtained by including in the analysis covariates that were collected for each period when they were time dependent. The multivariate model included (1) the period number, treated as a categorical variable, with the logarithm of the duration of exposure reported for each period as an offset; (2) sociodemographic characteristics; (3) time-dependent behavioral covariates; and (4) HSV-2 status, coded in 3 categories (i.e., HSV-2 negative throughout the study, became HSV-2 positive during the study, and HSV-2 positive at enrollment). The sociodemographic factors of interest for participants were age, religion, ethnic group, and alcohol consumption. The reported sexual behavior covariates were, for each period of follow-up, risky sexual behavior (defined as having at least 1 sexual contact unprotected by a condom), having a spousal partner, and number of nonspousal sex partners. To assess the relative importance of HSV-2 seropositivity on HIV incidence among young men, the proportion of HIV incident cases attributable to HSV-2 seropositivity was computed using the formula given by Bruzzi et al. [25]. 95% CIs were obtained by bootstrapping. The effect of HSV-2 status on the protective effect of male circumcision against HIV acquisition was assessed by testing the corresponding interaction term. Piecewise exponential proportional hazards modeling was repeated to identify the risk factors for HSV-2 incidence. To account for the median time to seroconversion (i.e., the window period), estimated to be 120 days for the assay used [26], and for the healing period following male circumcision, the effect of male circumcision on HSV-2 was analyzed for M12M21. This period included all participants tested for HSV-2 at least 240 days after male circumcision. The other factors were studied for M1M12. The risk of HIV infection is reduced by male circumcision [18 20] and associated with HSV-2 infection [27, 28]. Therefore, the analyses of the association between HSV-2 and male circumcision were repeated without data from participants who underwent HIV seroconversion during follow-up in order to determine whether the effect of male circumcision on HSV-2 was affected by HIV acquisition during follow-up. Finally, the association between HSV-2 incidence and health-seeking behavior, defined as at least 1 visit to a clinic for a genital problem during the 12-month period prior to a visit to the center, was HSV-2 status Negative during study Positive at enrollment Became positive during study Acquired HIV, subjects, proportion (%) Incidence rate ratio (95% CI) Adjusteda 3.3 (1.57.4) 7.0 (3.912.4) a Adjusted for circumcision status, age, religion, ethnic group, alcohol consumption, risky sexual behavior, marital status, and nonspousal partners (table 3). studied separately, univariately, and multivariately, using male circumcision status and the cofactors listed above. The CIs for the percentages were calculated using Bayesian estimation [29]. Statistical significance was defined as a P value of .05. Statistical analyses were performed using the statistical package SPSS for Windows, version 8 (SPSS), and R, version 2.6.2 [30]. Complementary epidemiological data. To estimate HSV-2 prevalence by age and sex among the population of Orange Farm, we used data from a representative sample of 436 men and 476 women aged 15 49 years from the community. These data were collected during a cross-sectional survey conducted in 2002 [31]. Blood samples were tested for HSV-2 serostatus, using the same HSV-2 assay as the one used in the present study. For men and women, HSV-2 prevalences were 31.7% (95% CI, 27.4% 36.1%) and 67.7% (95% CI, 63.3%71.7%), respectively. The HSV-2 prevalence was 1.8% (95% CI, 0.28%5.6%) among men aged 1519 years and 13.8% (95% CI, 7.9%21.7%) among men aged 20 24 years. Ethics review. The research protocol was reviewed and approved by the University of Witwatersrand Human Research Ethics Committee (Medical) on 22 February 2002 (protocol study M020104). The trial was also approved by the Scientific Commission of the ANRS (study protocol 1265; decision no. 50, approved in 2002), and authorization was obtained from the City of Johannesburg, Region 11, on 25 February 2002. Population characteristics. Of the 3274 participants enrolled in the trial, 5.9% were HSV-2 positive and 4.4% were HIV positive. A total of 2974 participants were HSV-2 negative at enrollment and completed at least 1 follow-up visit. Of these 2974 individuals, 67.2% were aged 20 years; 48.1% were Sotho and 35.7% were Zulu; and 1.9% were married. Intervention and control groups did not differ significantly in terms of the following baseline characteristics: HIV prevalence, 2.8% vs. 2.7%; risky sexual behavior, 46.0% vs. 46.0%; and mean (median) lifetime number of spousal and nonspousal sex partners, 4.4 (4.0) vs. 4.4 (4.0). HIV incidence and HIV IRR. Seventy-three new HIV infections were diagnosed during follow-up. Table 1 indicates the effect of HSV-2 status during follow-up on HIV incidence: the HIV IRRs among participants who were HSV-2 positive at recruitment and participants who became HSV-2 positive during follow-up were significantly higher than the IRR among participants who stayed HSV-2 negative during follow-up. The HIV IRR for participants who became HSV-2 positive was approximately twice as high as that for participants who were HSV-2 positive at baseline, with a borderline level of significance (IRR, 2.2; 95% CI, 0.955.1; P .067). The adjusted IRR was 2.1 (95% CI, 0.875.1; P .098). Population attributable fraction. Of the 73 new HIV infections diagnosed during follow-up, 48 (65.8%; 95% CI, Table 2. Herpes simplex virus type 2 (HSV-2) seroincidence and univariate effect of male circumcision. Analysis, group Control Intervention Uncircumcised Acquired HSV-2, subjects, no. Follow-up duration, person-years 3.54 (2.544.93) 2.33 (1.553.51) 3.81 (2.765.26) 2.09 (1.363.21) Incidence rate ratio (95% CI), by analysis type Intention to treata,b As treateda,b Control Intervention Circumcisedc Not applicable Not applicable Not applicable Not applicable a Obtained using a piece-wise exponential model, which was implemented with a Poisson log-linear model. Duration of exposure was the duration of each period for those staying HSV-2 negative and the duration of half the period for those becoming HIV positive. b Adjusted for all variables indicated in the first column. c For data obtained during follow-up visits at 12 and 21 months. d Defined as having at least 1 sexual contact during which a condom was not used. e At some point between enrollment and the follow-up visit at 3 months, the visits at 3 and 12 months, and/or the visits at 12 and 21 months. f Throughout the intervals between enrollment and the follow-up visit at 3 months, the visits at 3 and 12 months, and/or the visits at 12 and 21 months. 54.6%75.9%) were among HSV-2negative participants, 8 (11%; 95% CI, 5.2%19.4%) were among HSV-2positive participants, and 17 (23.3%; 95% CI, 15.1%34.2%) were among participants who got infected with HSV-2 during follow-up. The percentage of HIV infections occurring among HSV-2negative circumcised participants (64.9% [37 of 57]) was similar to that among uncircumcised participants (66.7% [10 of 15]). The HSV-2 window period had a limited impact on this percentage: of the 33 HIV infections occurring during M1-M12, 19 (57.6%; 95% CI, 41%73%) were among participants who remained HSV-2 negative during the M1-M21 period. On the basis of the percentage of participants with newly acquired HIV infection who were HSV-2 positive at recruitment or became HSV-2 positive during follow-up (34.2% [25 of 73]; 95% CI, 24.1% 45.4%) and the corresponding adjusted IRR (5.3; 95% CI, 3.1 8.9), we estimated that 27.8% (95% CI, 17.7%37.2%) of HIV incident cases among men were attributable to HSV-2 seropositivity or HSV-2 acquisition. Negative during study Positive at enrollment Became positive during study Acquired HSV-2, subjects, proportion (%) 102/2828 (3.6) 11/81 (13.6) 17/65 (26.2) Incidence rate ratio (95% CI) Adjusteda Effect of HSV-2 status on the protective effect of male circumcision against HIV acquisition. The protective effect of male circumcision against HIV acquisition did not differ with respect to HSV-2 status (P .93 for the interaction effect between randomization group and HSV-2 status). Among participants positive for HSV-2 at baseline, the protective effect of male circumcision against HIV acquisition was 0.37 (95% CI, 0.09 1.55; P .17) in the ITT analysis and 0.20 (95% CI, 0.04 0.97; P .046) in the AT analysis. For participants who were HSV-2 negative, the protective effect was 0.38 (95% CI, 0.22 0.66; P .001) in the ITT analysis and 0.24 (95% CI, 0.13 0.45; P .001) in the AT analysis. The protective effect of male circumcision against HIV acquisition among those who became HSV-2 positive during follow-up was 0.45 (95% CI, 0.16 1.27; P .13) in the ITT analysis and 0.28 (95% CI, 0.08 0.99; P .048) in the AT analysis. Risk factors associated with HSV-2 incidence. A total of 130 HSV-2 infections were diagnosed during follow-up, with 102 (78.5%; 95% CI, 70.9% 84.9%) among HIV-negative participants, 11 (8.5%; 95% CI, 4.5%14.1%) among HIV-positive participants, and 17 (13.1%; 95% CI, 8.0%19.6%) among participants who became HIV positive. Table 2 presents the number of HSV-2 infections observed during follow-up and the univariate effect of male circumcision on HSV-2 incidence as a function of randomization group and circumcision status. There was a borderline protective effect in the ITT analysis, and the effect became stronger and significant in the AT analysis. When both analyses were repeated for data from M1M21, the effect was, as expected, diluted in the ITT analysis (IRR, 0.87; 95% CI, 0.61 1.22; P .42), but it remained significant in the AT analysis (IRR, 0.70; 95% CI, 0.49 0.99; P .044). Table 3 presents findings of ITT and AT multivariate analyses of HSV-2 incidence. In both instances, the value of the protective effect of male circumcision and its level of statistical significance were close to the corresponding values from the univariate analyses (table 2). HSV-2 incidence was significantly associated with older age, risky sexual behavior, and HIV status at enrollment. Table 4 illustrates the strong association between HIV status and HSV-2 acquisition during follow-up. When participants with HIV seroconversion during follow-up were excluded from the analyses, the univariate ITT and AT IRRs of HSV-2 incidence became 0.71 (95% CI, 0.411.25; P .24) and 0.63 (95% CI, 0.36 1.11; P .11), respectively. The corresponding adjusted IRRs became 0.73 (95% CI, 0.39 1.38; P .34) and 0.50 (95% CI, 0.26 0.95; P .035), respectively. These values are close to the values reported in tables 2 and 3, indicating that the observed effect of male circumcision on HSV-2 acquisition could not have been due to the effect of male circumcision on HIV acquisition. Attendance at a health clinic for a health problem related to the genitals. The percentage of participants who attended a clinic for a health problem related to the genitals in the past 12 months was 10.8% (95% CI, 9.7%12.0%). Participants who attended a clinic were more likely to have been recently infected with HSV-2, as revealed by univariate analysis (IRR, 4.55; 95% CI, 2.94 7.02; P .001) and multivariate analysis (adjusted IRR, 3.31; 95% CI, 2.125.18; P .001). DISCUSSION The primary aim of this study was to assess the effect of HSV-2 status on HIV acquisition by men, using data collected during a male circumcision trial conducted in Orange Farm. We found a strong association between the incidences of these 2 viruses. Such association may be due to the fact that the viruses are both sexually transmitted and must share risk factors. It may also be due to the fact that one virus increases the risk of transmission of the other [2, 1114]. This study was conducted in an area with high HIV and HSV-2 prevalences among adults [32, 33]. As shown by data from a cross-sectional survey, the relatively low HSV-2 prevalence in our sample was likely due to the fact that participants were young men. The population fraction of HIV incidence due to HSV-2 among young men in this study was 25%, which is close to the lower bound of the estimates, ranging from 25% to 48%, obtained by modeling studies [34, 35]. These results suggest an overall substantial effect of HSV-2 status on the HIV epidemic. They further indicate that effective treatment of HSV-2 infection could possibly prevent 25% of new HIV infections among males. However, recent research has shown that acyclovir, the currently recommended agent for HSV-2suppressive therapy, does not reduce HIV acquisition among HSV2positive women [36]. This can be explained by the fact that on HIV transmission may be attributed to its effects on HSV-2, acyclovir does not cure HSV-2 infection. Our results also suggest (with a borderline level of statistical significance) that HIV incidence may have been twice as high among participants who became HSV-2 positive than among those who were HSV-2 positive at baseline. These results concur with those from a study conducted among commercial sex workers in South Africa [9], which suggested that recent HSV-2 seroconversion appeared more important than established HSV-2 infection for the acquisition of HIV. Finally, we found that the protective effect of male circumcision against HIV acquisition was not altered by HSV-2 status or HSV-2 acquisition. Our findings indicated that participants who were HIV positive at enrollment were more likely to acquire HSV-2. There was an independent and protective effect of male circumcision against HSV-2 acquisition by young males, which was significant only in the AT analysis. The protective effect was diluted in the ITT analysis, likely because of the crossover by 8.2% of participants in this study [18]. In the ITT analysis, the size of the protective effect of male circumcision against HSV-2 acquisition was consistent with results of a metaanalysis of observational studies, which showed a relative risk of 0.88 (95% CI, 0.771.01) [21], and with preliminary results from the Rakai male circumcision trial [37]. However, the AT analysis suggested a strong protective effect of male circumcision against HSV-2 acquisition. There are some limitations to this study. First, the window period of HSV-2 testing may have impacted the prevalence and incidence of HSV-2. Second, the crossover of participants was 8.2% and may explain the discrepancy between results from the ITT and AT analyses. Third, because the sample included young men among whom the HIV and HSV-2 prevalences were relatively low compared with those of the general population, our findings may not be generalizable. Finally, the participants were taking part in a randomized controlled trial, and the randomization procedure we used did not preclude selection bias. This study provides additional evidence supporting the promotion of male circumcision in Africa: male circumcision has the potential to reduce female-to-male transmission of HSV-2 and, thus, the spread of HSV-2, and it has been proven to reduce female-to-male transmission of HIV. The protective effect of male circumcision against HSV-2 acquisition is another finding that supports rolling out male circumcision programs in African countries with a low prevalence of male circumcision [38]. Because of the complex interplay between HSV-2, HIV, and male circumcision, further studies, particularly modeling studies, are needed to better understand their interactions not only in the short term, as studied by randomized controlled trials, but also in the long term. Such studies should provide a comprehensive investigation of the epidemiological and geographical distribution of HIV and HSV-2 in Africa, taking male circumcision prevalence into account. Part of the effect of male circumcision such as the reduction of genital herpetic lesions, which are associated with HSV-2 infection and may facilitate HIV transmission. However, this study contends that this effect is limited at the population level. Acknowledgments We thank all persons who agreed to take part in this study, answer the questions put to them, and provide swab samples; Gaph Sipho Phatedi, for managing the recruitment process; Yvon de La Soudire, for helping with management of the data set; Dr. Bhekuyise Gwala, Dr. George Shilaluke, and Dr. Dumiso Zulu, for performing circumcisions; Goliath Gumede, for performing the clinical investigation; Zodwa Nkosi, for interviewing all respondents; Bongiwe Klaas, for data capture; and Mabel Hunter, the recruitment staff, and all assistants (Cynthia Dlamini, Sidwell Dumisi, Benjamin Masitenyane, Robert Matodzi, Tsietsi Mbuso, Anthony Motha, Sibongiseni Mpetsheni, Jabulani Nhlapo, Joseph Ntsele, Male Chakela, Audrey Tshabalala, Donald Mashamba, and Nkululeko Nhlapo), for their cooperation and support. Lesley Short, Moses Mashiloane, Beulah Miller, Beverley Singh, Sarah Hloma, and the HIV serology laboratory of the National Institute for Communicable Diseases (Johannesburg, South Africa) provided technical assistance with laboratory testing.


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Joelle Sobngwi-Tambekou, Dirk Taljaard, Pascale Lissouba, Kevin Zarca, Adrian Puren, Emmanuel Lagarde, Bertran Auvert. Effect of HSV-2 Serostatus on Acquisition of HIV by Young Men: Results of a Longitudinal Study in Orange Farm, South Africa, Journal of Infectious Diseases, 2009, 958-964, DOI: 10.1086/597208