Differences in HIV risk factors between South African adolescents and adult women and their association with sexually transmitted infections

Abstract

Objectives: In sub-Saharan Africa, approximately 86% of HIV infections in adolescents aged 15-19 years occur among girls. Their heightened susceptibility is likely influenced by converging sociobehavioural and biological factors, although the relative contributions remain unclear. To address this, we compared known and hypothesised risk factors for HIV between cisgender adolescent girls and adult women in South Africa and evaluated the relationships between these factors and sexually transmitted infection (STI) status.

Methods: This cross-sectional observational study included adolescent (n=305; 14-19 years) and adult females (n=114; 25-35 years) in two South African provinces (Western Cape (WC), KwaZulu-Natal (KZN)). Demographic and sociobehavioural data were collected by questionnaire. Colposcopy was conducted to identify cervicovaginal abnormalities, and tests for bacterial vaginosis (BV), Chlamydia trachomatis, Neisseria gonorrhoeae and Trichomonas vaginalis were performed.

Results: Adults reported higher risk sexual behaviour than adolescents across multiple variables, although adolescents were more likely to have STIs than adults (62.8% vs 34.0%, respectively, p=0.0010 for WC; 42.5% vs 16.4%, respectively, p=0.0002 for KZN). Adolescents did, however, report earlier sexual debut (16 years old vs 17 years old, p<0.0001 for both sites) and KZN adolescents were more likely to use intravaginal sexual enhancers than adults (34.6% vs 20.6%, respectively, p=0.0417). Numbers of sexual partners (β-coefficient: 0.34, SE: 0.12, p=0.0054) and sex acts within the previous 3 months (β-coefficient: 0.25, SE: 0.09, p=0.0062) were associated with STIs in adolescents and trended to significance for adults. Intravaginal sexual enhancer use (KZN only; β-coefficient: 0.95, SE: 0.38, p=0.0118) and biological risk factors, including BV Nugent score (β-coefficient: 0.09, SE: 0.04, p=0.0257) and signs of cervicovaginal injury/inflammation (β-coefficient: 1.07, SE: 0.45, p=0.0171), were associated with STIs in adolescents but not adults.

Conclusions: Risk factors for STIs including HIV may differ between age groups of girls and women, and mitigation interventions may need to be tailored accordingly.

Keywords: AFRICA; HIV; Reproductive Tract Infections; WOMEN.

Figure 1. Vaginal hygiene practices and sexual enhancer use by South African adolescents and adults. Information was collected using interviewer-administered questionnaires. (A) Proportions of adolescents (Adol) and adults in KwaZulu-Natal (KZN) inserting different substances intravaginally for hygiene purposes (n=256). (B) Time of intravaginal hygiene practices. (C) Proportions of adolescents (n=188) and adults (n=63) in KZN and adults (n=50) in the Western Cape (WC) ingesting products for sexual enhancement. (D) Proportions of adolescents and adults in KZN using vaginal sexual enhancers externally for sexual enhancement. (E) Proportions of adolescents and adults in KZN using vaginal sexual enhancers internally for sexual enhancement. (F) Reported purpose of using sexual enhancers.

Figure 2. Sexually transmitted infections (STIs), bacterial vaginosis (BV), candidiasis (yeasts/hyphae) and cervicovaginal abnormalities in South African adolescents and adults. (A) Women were tested for Chlamydia trachomatis and Neisseria gonorrhoeae using the Xpert CT/NG assay, and for Trichomonas vaginalis using wet mount microscopy and the OSOM Trichomonas Rapid Test in KwaZulu-Natal (KZN). Women in the Western Cape (WC) were tested for these STIs using Primerdesign genesig kits. (B) BV was diagnosed using Nugent scoring. The presence of yeast and fungal hyphae was evaluated using a microscopy potassium hydroxide mount in KZN and examination of Gram-stained vaginal smears in WC. (C) Colposcopic images of the cervix and vagina were collected by the study nurses and then examined by the study gynaecologist to identify the presence of cervical or vaginal abnormalities. Participants were excluded from analysis if either or both vaginal and cervical images were not collected or blurred, with 325 women included. The heatmap shows the percentage of women with each abnormality. Proportions were compared using Fisher’s exact test and p values <0.05 were considered significant. CT, Chlamydia trachomatis; NG, Neisseria gonorrhoeae