Herpes simplex virus type 2 (HSV-2) is one of the most prevalent sexually transmitted infections (STIs) worldwide and is the cause of most genital herpes.1 The NHANES III survey showed that 16.2% of individuals aged 14 years or older were HSV-2 seropositive.2 The public-health significance of HSV-2 infection is tremendous, with an estimated annual direct medical cost of $984 million in the United States (U.S.).3 In adults, HSV-2 prevalence is associated with lower socioeconomic status, multiple sex partners, younger age at first intercourse, previous history of STIs, geography, race, and gender4–6; however, few studies have examined factors associated with HSV-2 incidence specifically within adolescents.
Coinfections of HSV-2 and HIV-1 are common as the 2 infections share many of the same risk factors. Immunosuppressed patients infected with HSV-2 have more frequent, severe, and persistent recurrences.4,7 Among HIV-1-infected individuals in the U.S., 60 to 70% are estimated to be seropositive for HSV-2 in general, and the prevalence is even higher, up to 80% to 95%, among blacks.4
A clear association has been established between HSV-2 and HIV-1.8–12 However, most studies are cross-sectional and do not evaluate the temporal order of HSV-2 and HIV-1 infection. Longitudinal studies have shown that HSV-2 infection is associated with HIV-1 acquisition, but little is known about the acquisition of HSV-2 among HIV-1-infected individuals. Assessing this relationship is important because HIV-infected persons with HSV-2 coinfections may be more likely to transmit HIV than those without coinfection. Therefore, in this study, we evaluated risk factors for prevalent and incident HSV-2 infections in both HIV-1-positive and HIV-1-negative adolescents.
Participants from the Reaching for Excellence in Adolescent Care and Health (REACH) cohort were included in this study.13,14 Between 1996 and 2000, adolescents who acquired HIV-1 through risk behaviors, mainly sexual activities (perinatal transmission or blood product contamination were excluded), and comparable seronegative adolescents (aged 12–19 years) were recruited into a longitudinal study at 15 clinical sites in the U.S. to investigate the natural history of HIV-1.13 The study design and methods for quarterly follow-up, HIV-1 testing, and viral-load measurement, and immunophenotyping of CD4+ counts, along with demographics, risk behavior, and other clinical data, have been previously described in detail.13,14 Serum samples taken at baseline and at the end of follow-up were tested for HSV-2 antibodies using a gG-based type-specific immunoblot assay. All tests were performed in the Central Laboratory at the Centers for Disease Control and Prevention in Atlanta.15,16 Other STIs, including gonorrhea, chlamydia, HIV-1, and HPV, were also tested at baseline and at each semiannual follow-up visit.17 At the time of the study visit, highly active antiretroviral therapy (HAART) was defined as a combination of 2 nucleoside reverse transcriptase inhibitors and either a protease inhibitor or a nonnucleoside reverse transcriptase inhibitor, or a zidovudine/lamivudine combination regimen plus another antiretroviral drug.
Based on HSV-2 serology at baseline and final visit, subjects were defined as seroprevalent (HSV-2 positive at baseline), seroincident (HSV-2 negative at baseline but seroconverted during follow-up), and seronegative (HSV-2 negative at baseline and throughout follow-up) cases. HIV-1 serostatus was assessed at each semiannual visit, and there were no HIV-1 seroconverters included in this analysis.
HSV-2 prevalence was calculated as the proportion of seroprevalent cases in the total population at baseline. HSV-2 incidence (100 person years [py]) was calculated using the number of seroincident cases divided by the total follow-up time for both seroincident and seronegative cases; baseline seroprevalent cases were excluded from this calculation. Assuming that all missing data were at random, Markov chain Monte Carlo methods were used to impute CD4+ count (1% missing), viral load (VL; 14%), sexual partners (2%), days since HIV-1 diagnosis (22%), and anal HPV (19%) using follow-up time, gender, age, race, and HSV-2 status to increase power. Colinearity between variables was assessed with all variables in general using Pearson and Spearman rank tests as appropriate. The r2 values were significant only for 2 variables: “ever taken antiretroviral therapy (ART) medications before the study” and “currently taking ART medications” (r2 = 0.72). The correlation between these variables is expected, and “currently taking ART medications” was used in the model because it better explains current CD4+ count and HIV-1 VL.
For the first part of the primary analysis, demographic characteristics and baseline clinical parameters known to be associated with HSV-2 infection were compared between seroprevalent cases and HSV-2 negative individuals at baseline (which included both seronegative and seroincident cases at the end of the study). Then, in the second part, using the follow-up data, seroincident and seronegative cases were compared to evaluate selected risk associations between the seroprevalent and seroincident cases. Based on multiple follow-up–visit data and excluding the baseline visit, a cumulative variable “ever during follow-up” was created for gonorrhea, chlamydia, anal HPV, survival sex (traded sex for food housing or drugs), engaged in receptive anal sex, homeless, smoked cigarettes, had ever drank alcohol, and used drugs. Total new sexual partners during follow-up were calculated, as well as median CD4+ count. HSV-2 seroprevalent and HSV-2 seronegative at baseline and HSV-2 seronegative and HSV-2 seroincident at end of follow-up characteristics were compared using t-test, chi-square, or Fisher exact tests as appropriate. Risk factors that were significant (P < 0.10) in the univariable analysis were included in the multivariable logistic regression.
Because the majority of the HSV-2 incident cases occurred in HIV-1-positive individuals, a subset analysis was performed on HIV-1-positive HSV-2-seroincident versus HIV-1-positive HSV-2-seronegative adolescents. For this analysis, we used a matched case-control design wherein cases were defined as being seroincident for HSV-2, and controls were seronegative for HSV-2 at the end of follow-up. Two controls were matched for each case based on follow-up time (± 90 days), which allowed the cases and the controls an equal amount of time to acquire HSV-2. Demographic characteristics and clinical parameters known to be associated with HSV-2 acquisition were compared between cases and controls, assessing potential differences through paired t test and McNemar χ2 test. Because the actual date of HSV-2 acquisition is unknown, baseline characteristics were used. Conditional logistic regression was used to estimate odds ratios (ORs) and associated 95% confidence intervals (95% CIs) for the association between CD4+ count (increment of 50 cells/mm3), HIV-1 VL (log transformed), and HSV-2 acquisition. Other potential risk factors, such as ART use, HAART use, other STIs, gender, race, and number of sexual partners also were assessed and adjusted in the models.
Five hundred and thirteen adolescents (386 females and 127 males) with baseline and end of follow-up HSV-2 serology data were included in this study. Of the eligible participants, 343 were HIV-1 seropositive, and 170 were HIV-1 seronegative. At baseline, prevalent HSV-2 infection was present in 179 (35%), and 47 (16%) incident cases were identified during a median follow-up period of 1.95 years, resulting in an incidence of 7.35 cases/100 py. Incidence rates tended to be higher among females (7.70 vs. 6.64/100 py), blacks (7.62 vs. 6.89/100 py), and HIV-1-positive participants (8.50 vs. 5.58/100 py); however, none of these differences were statistically significant.
Persons with prevalent HSV-2 infection were more likely to be heterosexual (81% vs. 69%), female (91% vs. 67%), black non-Hispanic (78% vs. 64%), HIV-1 positive (82% vs. 59%), and coinfected with chlamydia (25% vs. 16%). Perhaps surprisingly, fewer HSV-2-infected participants reported smoking cigarettes (47% vs. 59%) than HSV-2-negative subjects; however, 58% of HSV-2 seronegatives at baseline who reported smoking became HSV-2 seropositive at the end of the study (Table 1). In the multivariable model, being female (OR, 7.46; 95% CI, 3.12–17.83), HIV-1 positive (OR, 2.94; 95% CI, 1.75–4.96), uncertainty of sexual preference (OR, 3.87; 95% CI, 1.31–11.42), and being Hispanic (OR, 0.42; 95% CI, 0.21–0.84) remained significantly different between seroprevalent and seronegative persons (Table 2).
Likewise, upon comparison of HSV-2 incident cases and HSV-2 seronegatives, the seroincident subjects were older (19.4 vs. 18.8 years), and during follow-up, were more likely to have been infected with gonorrhea (21% vs. 9%), had ever consumed alcohol (51% vs. 32%), used drugs (57% vs. 37%), or had a greater number of sexual partners (mean 6.57 vs. 3.44) than HSV-2-seronegative subjects (Table 1). In the multivariable model, only having used drugs during the follow-up time (OR, 2.31; 95% CI, 1.23–4.34) remained significantly different between seroincident and seronegative persons (Table 2).
A total of 197 (57%) of HIV-1-positive adolescents (124 females and 73 males) had negative HSV-2 serology at the time the study was started and of these, 33 tested HSV-2 positive during follow-up. For the case-control analysis, the 33 HIV-1-infected persons who acquired HSV-2 were matched to 63 of the HIV-1-positive/HSV-2-negative individuals who had been followed an average of 940.36 and 906.89 days, respectively. Baseline sociodemographic and clinical characteristics are shown in Table 3. Cases and controls did not differ by age, gender, race, or the presence of other STIs. In the univariable analysis, compared with the controls, cases were more likely to have engaged in survival sex (15.2% vs. 3.2%), had higher CD4+ counts (568.9 vs. 451.4 cells/mm3), and had lower HIV-1 VLs (3.5 vs. 3.9 Log VL) at baseline (Table 3). The controls tended to be more likely to be on HAART than cases, although the numbers are small. In the multivariable model, CD4+ count increase by 50 cell/mm3 (OR, 1.17; 95% CI, 1.04–1.31) remained significantly different between cases and controls.
HSV-2 prevalence rates were higher in the REACH cohort (35%) compared with adolescents (1.6%) of similar age14–19 from NHANES, during the study period.18 Most factors associated with HSV-2 seroprevalence at study baseline are similar to those reported in previous studies. As in prior studies, the prevalence was relatively higher (39%) among black non-Hispanics than among Hispanics (21%). In the most recent data from NHANES III, overall HSV-2 seroprevalence was 39.2% in black non-Hispanics (48% in women vs. 29% in men) as compared with 12.3% (15.9% in women and 8.7% in men) in white non-Hispanics and 10.1% (13.2% in women and 7.5% in men) in Mexican Americans,2 similar to rates in suburban primary care offices.19 HSV-2-prevalent individuals were also more likely to be females (r2, 0.53 with being heterosexual) and HIV-1 positive. The cohort is composed of 76% females, and a stratified analysis by gender could not be conducted due to limited power; however, a sensitivity analysis among females showed similar results to those presented in this study (data not shown). Adolescents who reported to be unsure of their sexual preference were also likely to be HSV-2 seroprevalent. These individuals were more likely to be HIV-positive, engage in anal sex, and be involved in survival sex, and had a higher number of sex-partners, which could indicate that they were engaging in sexual acts to help determine their sexuality (data not shown).
Despite the high initial prevalence of HSV-2 among participants, HSV-2 incidence rates were high in the REACH cohort (7.35 per 100 py) compared with the general U.S. population (0.18 per 100 py)18; however, it was at the lower end of what has been reported in some special populations. These estimates of HSV-2 incidence are conservative because HSV-2 was tested only at 2 visits, the first and last, and thus the actual date of seroconversion was likely sooner than the date of the final follow-up visit. Among HIV-1-negative individuals attending U.S. STD clinics (RESPECT cohort), an incidence of 11.7 per 100 py was reported.20 Likewise, studies among women attending STD clinics in the U.S. have reported incidence ranging from 5.7 to 20.5 per 100 woman years21,22 and similarly 4.9 to 14.2 per 100 py in other populations.6,23,24
Factors associated with HSV-2 seroprevalence at baseline differed from factors associated with HSV-2 seroincidence. HSV-2-seroprevalent cases differed demographically, such as with race and gender, and risk behaviors such as sexual preferences, and HIV status from HSV-2-seronegative individuals at baseline. Persons who experienced HSV-2 seroincidence during follow-up were more likely to report drug use and a higher numbers of new sexual partners when compared with individuals who remained HSV-2 seronegative. Seroincident cases were more likely to be HIV-1 seropositive, and the trend was similar for drug use and coinfection with gonorrhea as in seroprevalent individuals. Having only had such data at the time of initial evaluation and at the end of the follow-up period, we acknowledge the lack of precision in our evaluation of time-dependent factors. Here, we used the baseline measurements for the prevalence study; but for the seroincident study, we either could only ascertain variables such as drug and alcohol use cumulatively for all follow-up visits or used the data reported at the time of the last visit. Future studies should assess HSV-2 serology at each visit to correspond to the risk factor at respective visits.
In the subset analysis of HIV-1-positive individuals who acquired HSV-2 during follow-up, persons with higher CD4+ counts at baseline were more likely to acquire HSV-2 than those with lower CD4+ counts at baseline. Likewise, lower VL was associated with HSV-2 acquisition, but only CD4+ was significant in the multivariable analysis. CD4+ count is a strong indicator of the disease state and health of HIV-1-positive patient. The relatively healthy adolescents in the REACH study, as indicated by higher CD4+ counts, might also be more physically active than the sicker ones and therefore more likely to engage in risk behaviors, making them susceptible to HSV-2, as seen in other STI studies.25,26 These results are similar to a follow-up study done in San Francisco and elsewhere, showing that HIV-1-positive individuals on HAART were more likely to develop an STD compared with those not on HAART.27,28
The current study is a multicenter study, and unlike other studies from specific clinics or sites, where data may disproportionately represent certain social and sexual networks, our estimates may be more representative for at-risk adolescents in the U.S., in general. Our results indicate that adolescents were engaging in activities that made them susceptible to HSV-2 infection even after being infected with HIV-1 and add to the recommendation for continuing risk reduction counseling for persons with HIV, i.e., “prevention for positives.”
1. Looker KJ, Garnett GP, Schmid GP. An estimate of the global prevalence and incidence of herpes simplex virus type 2 infection. Bull World Health Organ 2008; 86:805–812, A.
2. Seroprevalence of herpes simplex virus type 2 among persons aged 14–49 years—United States, 2005–2008. MMWR Morb Mortal Wkly Rep 2010; 59:456–459.
3. Szucs TD, Berger K, Fisman DN, et al.. The estimated economic burden of genital herpes in the United States. An analysis using two costing approaches. BMC Infect Dis 2001; 1:5.
4. Gupta R, Warren T, Wald A. Genital herpes. Lancet 2007; 370:2127–2137.
5. Freeman EE, Weiss HA, Glynn JR, et al.. Herpes simplex virus 2 infection increases HIV acquisition in men and women: Systematic review and meta-analysis of longitudinal studies. AIDS 2006; 20:73–83.
6. Tassiopoulos KK, Seage G III, Sam N, et al.. Predictors of herpes simplex virus type 2 prevalence and incidence among bar and hotel workers in Moshi, Tanzania. J Infect Dis 2007; 195:493–501.
7. Mahiane SG, Legeai C, Taljaard D, et al.. Transmission probabilities of HIV and herpes simplex virus type 2, effect of male circumcision and interaction: A longitudinal study in a township of South Africa. AIDS 2009; 23:377–383.
8. del Mar Pujades Rodriguez M, Obasi A, Mosha F, et al.. Herpes simplex virus type 2 infection increases HIV incidence: A prospective study in rural Tanzania. AIDS 2002; 16:451–462.
9. Mertz KJ, Trees D, Levine WC, et al.. Etiology of genital ulcers and prevalence of human immunodeficiency virus coinfection in 10 US cities. The Genital Ulcer Disease Surveillance Group. J Infect Dis 1998; 178:1795–1798.
10. Watson-Jones D, Weiss HA, Rusizoka M, et al.. Effect of herpes simplex suppression on incidence of HIV among women in Tanzania. N Engl J Med 2008; 358:1560–1571.
11. Delany-Moretlwe S, Lingappa JR, Celum C. New insights on interactions between HIV-1 and HSV-2. Curr Infect Dis Rep 2009; 11:135–142.
12. Reynolds SJ, Risbud AR, Shepherd ME, et al.. Recent herpes simplex virus type 2 infection and the risk of human immunodeficiency virus type 1 acquisition in India. J Infect Dis 2003; 187:1513–1521.
13. Rogers AS, Futterman DK, Moscicki AB, et al.. The REACH Project of the Adolescent Medicine HIV/AIDS Research Network: Design, methods, and selected characteristics of participants. J Adolesc Health 1998; 22:300–311.
14. Wilson CM, Houser J, Partlow C, et al.. The REACH (Reaching for Excellence in Adolescent Care and Health) project: Study design, methods, and population profile. J Adolesc Health 2001; 29:8–18.
15. Schmid DS, Brown DR, Nisenbaum R, et al.. Limits in reliability of glycoprotein G-based type-specific serologic assays for herpes simplex virus types 1 and 2. J Clin Microbiol 1999; 37:376–379.
16. Moscicki AB, Ellenberg JH, Farhat S, et al.. Persistence of human papillomavirus infection in HIV-infected and -uninfected adolescent girls: Risk factors and differences, by phylogenetic type. J Infect Dis 2004;190:37–45.
17. Tsai CS, Shepherd BE, Vermund SH. Does douching increase risk for sexually transmitted infections? A prospective study in high-risk adolescents. Am J Obstet Gynecol 2009; 200:38 e1–38 e8.
18. Xu F, Sternberg MR, Kottiri BJ, et al.. Trends in herpes simplex virus type 1 and type 2 seroprevalence in the United States. JAMA 2006; 296:964–973.
19. Leone P, Fleming DT, Gilsenan AW, et al.. Seroprevalence of herpes simplex virus-2 in suburban primary care offices in the United States. Sex Transm Dis 2004; 31:311–316.
20. Gottlieb SL, Douglas JM Jr, Foster M, et al.. Incidence of herpes simplex virus type 2 infection in 5 sexually transmitted disease (STD) clinics and the effect of HIV/STD risk-reduction counseling. J Infect Dis 2004; 190:1059–1067.
21. Gallo MF, Warner L, Macaluso M, et al.. Risk factors for incident herpes simplex type 2 virus infection among women attending a sexually transmitted disease clinic. Sex Transmit Dis 2008; 35:679–685.
22. Wald A, Langenberg AG, Krantz E, et al.. The relationship between condom use and herpes simplex virus acquisition. Ann Intern Med 2005; 143:707–713.
23. Cachay ER, Frost SD, Poon AF, et al.. Herpes simplex virus type 2 acquisition during recent HIV infection does not influence plasma HIV levels. J Acquir Immun Defic Syndr 2008;47:592–596.
24. Tobian AA, Charvat B, Ssempijja V, et al.. Factors associated with the prevalence and incidence of herpes simplex virus type 2 infection among men in Rakai, Uganda J Infect Dis 2009; 199:945–949.
25. Shafer LA, Nsubuga RN, White R, et al.. Antiretroviral therapy and sexual behavior in Uganda: a cohort study. AIDS 2011; 25:671–678.
26. Park WB, Jang HC, Kim SH, et al.. Effect of highly active antiretroviral therapy on incidence of early syphilis in HIV-infected patients. Sex Transm Dis 2008; 35:304–306.
27. Scheer S, Chu PL, Klausner JD, et al.. Effect of highly active antiretroviral therapy on diagnoses of sexually transmitted diseases in people with AIDS. Lancet 2001; 357:432–435.
© Copyright 2012 American Sexually Transmitted Diseases Association
28. Hoots BE, Hudgens MG, Cole SR, et al.. Lack of association of herpes simplex virus type 2 seropositivity with the progression of HIV infection in the HERS cohort. Am J Epidemiol 2011; 173:837–844.