Article Text
Abstract
Objective To estimate the prevalence and describe the patterns of concurrent human papillomavirus (HPV) and STIs and associated factors among HIV-negative young Western Cape, South African women participating in the Efficacy of HPV Vaccine to Reduce HIV Infection (EVRI) trial.
Methods HIV-negative women aged 16–24 years old were enrolled in the EVRI trial (NCT01489527) and randomised to receive the licensed four-valent HPV vaccine or placebo. At study entry, participants were clinically evaluated for five STIs: herpes simplex virus type 2 (HSV-2), chlamydia, gonorrhoea, syphilis and disease-causing HPV genotypes (6/11/16/18/31/33/35/39/45/51/52/56/58/59/68). Demographic and sexual history characteristics were compared among women with STI co-infections, single infection and no infection using Pearson χ2 and Mann-Whitney tests. ORs were calculated to evaluate factors associated with STI co-infection prevalence.
Results Among 388 young women, STI co-infection prevalence was high: 47% had ≥2 concurrent STIs, 36% had a single STI and 17% had none of the five evaluated STIs. HPV/HSV-2 (26%) was the most prevalent co-infection detected followed by HPV/HSV-2/Chlamydia trachomatis (CT) (17%) and HPV/CT (15%). Co-infection prevalence was independently associated with alcohol use (adjusted OR=2.01, 95% CI 1.00 to 4.06) and having a sexual partner with an STI (adjusted OR=6.96, 95% CI 1.53 to 30.08).
Conclusions Among high-risk young women from underserved communities such as in Southern Africa, a multicomponent prevention strategy that integrates medical and behavioural interventions targeting both men and women is essential to prevent acquisition of concurrent STI infections and consequent disease.
Trial registration number NCT01489527; Post-results.
- HPV
- CHLAMYDIA INFECTION
- HSV
- GONORRHOEA
- SYPHILIS
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Introduction
As one of the most common STIs, human papillomavirus (HPV) infection accounts for nearly a third of infection-related cancers worldwide.1 The African continent, particularly sub-Saharan Africa, experiences a disproportionate burden of these HPV-associated cancers.2 ,3 Sub-Saharan Africa also has a high burden of HIV4 and other STIs such as chlamydia, gonorrhoea, trichomoniasis, herpes simplex virus type 2 (HSV-2) and syphilis;5–7 STIs implicated in HIV acquisition and transmission.8–10 Similar to the other STIs, there is growing evidence that HPV may also increase susceptibility to HIV acquisition.11–13 These and other published reports of STIs in Africa indicate that both urban and rural Sub-Saharan African men and women are at high risk for acquiring concurrent STIs.14 ,15 In such resource-constrained settings, a host of factors likely converge to influence STI co-infection risk including early age of sexual debut, lower education, migration, higher number of lifetime sex partners, concurrent sexual relationships and previous infection with an STI.6 ,7
Often, STIs such as chlamydia and gonorrhoea are asymptomatic16 ,17 and in the absence of screening and appropriate treatment, these STIs could have severe consequences for the sexual and reproductive health of women. Untreated STIs accelerate women's risk for pelvic inflammatory disease leading to chronic pelvic pain and infertility.18 ,19 Pregnant women with untreated STIs are at high risk for obstetric complications as well as fetal and neonatal morbidity and mortality.19 Given these long-term sequelae, epidemiological data on the prevalence and types of STI co-infections among high-risk, HIV-negative young women remain critical for targeted STI prevention and intervention programmes that include routine screening, referral for appropriate treatment and HPV vaccination.
The current analysis estimates the prevalence and describes patterns of concurrent STIs among HIV-negative, young South African women with any of the following five STIs: chlamydia, gonorrhoea, syphilis, HSV-2 and disease causing HPV genotypes in the Efficacy of HPV Vaccine to Reduce HIV Infection (EVRI) study. A secondary aim was to assess factors associated with prevalent concurrent STIs.
Materials and methods
Study population
Young female residents of the Western Cape, South Africa, were enrolled from November 2012 to July 2013 in a phase II randomised placebo controlled double-blind trial, the EVRI trial (NCT01489527) that used the licensed four-valent HPV (4vHPV) vaccine (Gardasil).20 Women were recruited from the Bloekombos primary healthcare clinic and Kraaifontein Day Hospital and were enrolled if they met the following eligibility criteria: (1) aged 16–24 years; (2) no history of abnormal Pap smear; (3) reported having vaginal intercourse; (4) not currently pregnant or breastfeeding; (5) HIV negative; (6) no autoimmune disease requiring steroid use; (7) not had a splenectomy; (8) not currently enrolled in an HIV prevention trial; (9) no IV drug use in the past 6 months; (10) no serious allergic reactions history requiring medical attention; (11) no allergies to aluminium, yeast or benzonase; (12) no previous HPV vaccination; (13) willingness to comply with four scheduled visits within 7 months of enrolment; and (14) agreed to use effective contraception during sexual intercourse for the vaccination period.
Women were randomised 1:1 to receive the 4vHPV vaccine or placebo (saline) at enrolment, months 2 and 6. Participants were followed for 1 month after the final dose when individual unblinding occurred and women from the placebo arm were offered the Gardasil vaccine. This analysis focuses on STI co-infections at the enrolment visit, prior to vaccine allocation.
The study protocol was approved by the Institutional Review Boards of the University of South Florida, USA (number Pro00005120), and Stellenbosch University (number N11/06/174), South Africa. Additionally, the protocol followed South African policies and ethical guidelines concerning parental permission for children to participate in research studies.
Study procedures
At enrolment, participants completed a tablet-based questionnaire using a computer-assisted self-interview available in English, Xhosa and Afrikaans that assessed their sexual history, health and sociodemographic characteristics. Very few women reported any symptoms, mainly vaginal discharge. Urine specimens for chlamydia and gonorrhoea testing were collected and sera for syphilis testing and HSV-2 antibody status assessment were obtained. A study physician performed a physical examination including a speculum exam of the vagina and cervix. Specimens for HPV detection were collected from the vulva/labia and from the endocervix/ectocervix followed by a digital vaginal exam. Samples for HPV detection were obtained using a prewetted Dacron cotton swab placed in specimen transport medium (STM) (Digene Hybrid Capture test kit; Digene).
Laboratory analyses
Chlamydia and gonorrhoea were detected from urine specimens with the Anyplex CT/Neisserria gonorrhoeae (NG) real-time detection method (Seegene, South Korea). Syphilis was detected using the Captia Syphilis (Treponema pallidum)-G assay (Trinity Biotech, Jamestown, New York, USA). All specimens positive for syphilis were confirmed positive by a repeat test with the same assay.21 The Captia Syphilis (T. pallidum)-G test may test positive in patients with active or inactive disease and those with previously treated infection.21 HSV-2 antibody status was measured by the Captia HSV-2 type specific IgG enzyme-linked immunoassay (Trinity Biotech). A primary HSV-2 infection or clinical recurrence cannot be determined from a serological test. However, HSV-2 is a lifelong infection with potential for recurrent episodes in the absence of chronic suppressive therapy, and intermittent viral shedding is common even in the absence of clinical symptoms.22 Thus, for this analysis, an HSV-2 antibody-positive test was considered a current infection.
HPV DNA was detected by PCR. The Qiagen Media Kit was used to extract genomic DNA from cervical specimens and then amplified by PCR with the PGMY09/11 L1 consensus primer system and AmpliTaq Gold polymerase (Perkin-Elmer, Norwalk, Connecticut, USA). HPV DNA genotyping was performed on all cervical specimens using the Linear Array HPV Genotyping Test (Roche Diagnostics) which detects 37 HPV genotypes (6, 11, 16, 18, 26, 31, 33, 35, 39, 40, 42, 45, 51, 52, 53–55, 56, 58, 59, 61, 62, 64, 66, 67, 68, 69–73, 81–84, 89, IS39). The Linear Array test is unable to detect HPV 52 co-infections in the presence of HPV 33, 35 or 58, so prevalence of HPV 52 infection might be underestimated. Although the assay provides estimates for all 37 HPV types, this analysis focuses on the HPV genotypes known to cause disease in women, specifically cervical cancer (HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 68), and genital warts (HPV 6 and 11).23
Statistical analysis
Data were analysed using SAS V. 9.4 software (SAS Institute, Cary, North Carolina, USA). A p value of less than 0.05 was considered statistically significant. Women were categorised into three groups by their STI status: no infection, single infection or co-infection. No infection was defined as testing negative for all five STIs, specifically chlamydia, gonorrhoea, syphilis, HSV-2 or disease-causing HPV genotypes; single infection was defined as having any one of the five STIs, and co-infection was defined as having two or more of the five STIs concurrently. Enrolment sociodemographic characteristics and sexual behaviour were compared between the three groups using the Mann-Whitney test for continuous variables, and Fisher's exact test or Pearson χ2 test for categorical variables. Demographic variables were chosen based on associations with STIs shown in previous studies. To assess factors associated with STI status, a multinomial logistic regression model compared single infection versus no infection, and co-infection versus no infection. ORs and 95% CIs were computed as a measure of the association. Backwards elimination was performed to assess factors independently associated with single infection or co-infection with p value≤0.20 chosen as the a priori cut-off for retention in the multivariable model.24 The final models were adjusted for age as it was associated with HPV and STI prevalence in previous EVRI analyses.20
Results
Of the 402 enrolled women, 3 with false-negative results for HIV, 5 with inadequate samples for HPV detection and 6 with specimens that were β-globin negative and HPV DNA negative were excluded, resulting in a total of 388 women included in the final analysis. Similar to previously reported EVRI analyses,20 STI prevalence was high in these women: HPV (57.5%), HSV-2 antibodies (46%), chlamydia (33.5)%, gonorrhoea (11.1%) and syphilis (5.9%) (see online supplementary table S1). STI co-infection prevalence was also high among the 388 women, 183 (47%) had co-infections, 138 (36%) had a single infection and 67 (17%) had no infections (figure 1A). Sociodemographic and sexual health characteristics were similar between the three groups with regard to age, education, marital status, median age at first vaginal sex, birth control use and history of pregnancy (table 1). Although the median number of lifetime male sexual partners was low, there was a wide range of reported sex partners in all three groups: ‘no infection’ (median 2: range, 1–22), ‘single infection’ (median 3: range, 1–21) and ‘co-infections’ (median 3: range, 1–24), respectively. A higher proportion of women with co-infections (56.2%) reported three or more lifetime number of male sexual partners compared with women with a single infection (50.4%) or women with no infections (40%); however, the number of partners was not significantly different between the three groups. Alcohol use (p=0.02) and having a sexual partner with an STI (p=0.01) were significantly different across the three groups of women (table 1). Online supplementary tables S2– S6 describe sociodemographic and sexual health characteristics associated with individual STIs.
supplementary table S1
Sexually transmitted infections and co-infection proportions among women (n=388) in the EVRI Trial (HPVa, Chlamydia, Gonorrhea, Syphilis, or HSV-2)
supplementary table S2
Selected demographic and sexual health characteristics among HIV-negative young South African women (n=388) with and without HPVa infection
supplementary table S3
Selected demographic and sexual health characteristics among HIV-negative young South African women (n=388) with and without chlamydia (CT) infection
supplementary table S4
Selected demographic and sexual health characteristics among HIV-negative young South African women (n=388) with and without gonorrhea infection
supplementary table S5
Selected demographic and sexual health characteristics among HIV-negative young South African women (n=388) with and without syphilis infection
supplementary table S6
Selected demographic and sexual health characteristics among HIV-negative young South African women (n=388) with and without HSV-2 infection
Prevalence and patterns of concurrent STIs
Figure 2 shows the number of women that tested positive for each of the five STIs and the proportion that were positive for single or multiple concurrent infections for each STI. Nearly 83% of women with syphilis, 100% of women with gonorrhoea, 84% of women with chlamydia, 75% of women with HSV-2 and 69% of women with disease causing HPV genotypes were co-infected with at least one other STI (figure 2). Although disease-causing HPV types had the highest overall prevalence among the five STIs (57.5%), HPV-infected women had the lowest prevalence of co-infections, with nearly a third of the women (31%) having no other concurrent STIs. In contrast, the highest prevalence of co-infections was among women with gonorrhoea with all women having at least one co-infection, 37% co-infected with two STIs and 37% co-infected with ≥3 STIs.
Among women with a co-infection (n=183) (figure 1C), HPV/HSV-2 (26%) was the most prevalent co-infection detected. An additional 33% of women (n=60) tested positive for HPV/HSV-2 co-infections concurrently with other STIs: HPV, HSV-2, chlamydia (17%); HPV, HSV-2, chlamydia, gonorrhoea (8%); HPV, HSV-2, syphilis (4%); HPV, HSV-2, gonorrhoea (2%); HPV, HSV-2, chlamydia, syphilis (1%) (figure 1C). Concurrent HPV and chlamydia infections were detected in 48% of women with STI co-infections. Of these, 33% were detected in the presence of other STIs: HPV, chlamydia, HSV-2 (17%); HPV, chlamydia, gonorrhoea, HSV-2 (8%); HPV, chlamydia, gonorrhoea (5%); HPV, chlamydia, syphilis (1%); and HPV, chlamydia, HSV-2, syphilis (1%). One young woman had all five STIs detected.
Factors associated with prevalent single infection and co-infections
Co-infection with STIs was independently associated with alcohol use (adjusted OR (aOR)=2.01, 95% CI 1.00 to 4.06) and having a sexual partner with an STI (aOR=6.96, 95% CI 1.53 to 30.08) compared with women with no STIs (table 2). Education, marital status, birth control use, tobacco use, ever been pregnant and lifetime number of sex partners were not significantly associated with prevalence of co-infections or single infection compared with women with no STIs after adjusting for age.
Discussion
In this cohort of young HIV-negative Western Cape, South African women, we detected a high prevalence (47%) of two or more concurrent STIs, specifically chlamydia, gonorrhoea, syphilis, HSV-2 and disease-causing HPV types. The most prevalent co-infection detected was HPV/HSV-2 and this combination also frequently occurred with the other three STIs. There were no significant differences between women with a single infection compared with women with no infection in terms of their sociodemographic and sexual health characteristics. However, co-infection prevalence was independently associated with alcohol use and having a sexual partner with an STI. Although these behavioural data were self-reported, the high prevalence of STI co-infections suggests that young Western Cape women are rapidly acquiring not just a single STI but multiple concurrent infections after sexual debut.
Co-infections with chlamydia, gonorrhoea, HSV-2 and syphilis have been reported among HIV-negative women in sub-Saharan Africa but the pattern varies geographically with higher prevalence of HSV-2, gonorrhoea and chlamydia co-infections in South Africa7 ,14 ,25 versus gonorrhoea and syphilis co-infections in Tanzania and Zambia.7 Women in all three studies were slightly older with a mean age ≥25 years7 ,14 ,25 compared with a median of 20 years in our study; however, younger women (<25 years old) in these studies were more likely to have prevalent STIs and acquire STI co-infections.7 ,14 ,25 ,26
Almost all women with co-infections (99%) in our study harboured either an HPV or HSV-2 infection, possibly a reflection of the high prevalence of these two STIs globally. Another explanation is that these two STIs are more likely to be detected because HSV-2 is a lifelong infection and HPV infection can persist for years. It is plausible that HPV and HSV-2 infections may elevate the risk of acquiring other bacterial STIs (chlamydia, gonorrhoea and syphilis). Previous reports indicate that African women with a prevalent HSV-2 infection are at risk to acquire chlamydia,25 gonorrhoea25 ,27 and syphilis.27 Similarly, these bacterial and viral STIs are known to increase HIV acquisition and transmission.8–13 Some biological explanations proposed are that STIs may amplify inflammatory processes changing the genital tract milieu which increases susceptibility to other STIs.28 Among adolescent females, an immature cervix29 and variability in the composition of vaginal microbiota after puberty30 are additional biological factors that could influence STI acquisition.29 ,30 However, in the current prevalence study temporality cannot be established limiting our ability to determine which STI was acquired first.
Of concern, among HPV-infected women, concurrent infections with chlamydia, gonorrhoea and HSV-2 have been linked to HPV persistence and increased risk of cervical neoplasia.31–34 We have previously reported a high prevalence of high-risk HPV genotypes (56%) in this population.20 Thus, given the high prevalence of co-infections (69%) among women with disease-causing HPV types in this study, estimating factors that influence this co-infection prevalence in women was critical. In our adjusted analyses, co-infection prevalence was increased in women reporting alcohol use and a male sexual partner with a history of an STI. The low median lifetime number of male sexual partners in our study suggests that in such high-risk populations, a male sexual partner's STI history may be more important than a woman's lifetime number of sexual partners. Thus, to reduce STI co-infection prevalence in young women, medical and behavioural interventions that include STI screening and treatment programmes, condom use and HPV vaccination must target both women and men.
Although the EVRI trial was prospective, because of its short follow-up period of 7 months, we were unable to assess incidence of STI co-infections. Future studies are needed to clarify the relationship between bacterial and viral STI co-infection incidence and evaluation of younger women's risk of acquiring these infections, either concurrently or sequentially. Our study findings may not be generalisable to all South African young women and may not reflect the STI and risk conditions in other sub-Saharan settings. However, a major strength of our study is its relatively large sample size that allowed estimation of single and concurrent STI prevalence as well as STI co-infection patterns. The demographic and behavioural data were based on self-report that could be susceptible to recall and social desirability biases. To minimise these biases, we administered a tablet-based questionnaire in the local languages rather than an interviewer-administered survey. For those women reporting multiple sexual partners, there was no way to determine concurrent sexual relationships which may have influenced the observed high prevalence of co-infections. It is difficult to establish whether women who tested positive for HSV-2 and syphilis have active disease. However, HSV-2 is a chronic infection with recurrent episodes and viral shedding in the absence of continual suppressive therapy. Finally, the prevalence of other genital tract infections such as Trichomonas vaginalis and Mycoplasma genitalium was not assessed.
STI co-infection prevalence was high in this cohort of young HIV-negative Western Cape women despite a low median lifetime number of male sexual partners. Also, STI co-infection prevalence was independently associated with alcohol use and having a male sex partner with an STI. These data suggest the need for a multicomponent STI prevention strategy for both men and women that incorporates medical and behavioural interventions including integration of HIV, STI and cervical screening, referral to appropriate treatment and HPV vaccination.
Key messages
STI co-infection prevalence is high with 47% of HIV-negative young South African women having two or more concurrent STIs.
STIs can have severe consequences on the sexual and reproductive health of women and may increase the likelihood of HIV acquisition.
A multicomponent STI prevention strategy is essential to reduce STI co-infections and should include both genders.
Acknowledgments
The authors acknowledge the contributions of Charlotte Lawn, Wendy Adendorff, Zukiswa Gloria Ncume, Kayoko Kennedy, Dale Barrios, Jeannie Vaughn, David Jackson, Shahieda Isaacs, Nafiisah Chotun and all study participants, without whom this study would not have been possible.
References
Footnotes
Handling editor Jackie A Cassell
Contributors ARG, LJM and SLS conceptualised study. ARG, LJM, UP and SLS contributed to data analyses. LJM and UP wrote manuscript. MHB and MZ directed data collection. RHG and SE performed laboratory analyses. All coauthors contributed to study design, interpretation of findings, reviewing and editing manuscript.
Funding This research was supported in part by a research grant from Investigator-Initiated Studies Program of Merck Sharp & Dohme. The opinions expressed in this paper are those of the authors and do not necessarily represent those of Merck Sharp & Dohme. Merck (IISP39582) was the main sponsor of this trial and provided the study product. This work was also supported by the National Cancer Institute at the National Institutes of Health (Cancer Prevention Fellowship R25T CA147832 to SLS).
Competing interests ARG is a member of Merck research advisory boards. ARG and SLS received research funding from Merck. MFSvdL received research funding from Sanofi-Pasteur MSD; he is a co-investigator in a Sanofi-Pasteur-MSD HPV vaccine trial; he sat on a vaccine advisory board of GSK; his institution received in-kind contribution for an HPV study from Stichting Pathologie Onderzoek en Ontwikkeling; his institution receives research funding from Janssen Infectious Diseases and Vaccines.
Ethics approval Institutional Review Board, University of South Florida (number Pro00005120) and Health Research Ethics Committee, Stellenbosch University (number N11/06/174).
Provenance and peer review Not commissioned; externally peer reviewed.