South Africa has overlapping high burdens of HIV and sexually transmitted infections (STIs). Higher rates of STI have been reported among people living with HIV (PLHIV) because of biological and epidemiological synergy.¹ For example, men who have sex with men (MSM) with rectal Chlamydia trachomatis or Neisseria gonorrhoeae infection are 2 to 3 times more likely to acquire HIV infection compared to those without a rectal STI.²

Syndromic management is the standard of care for STIs in South Africa.³ This approach means that empirical antibiotic treatment is provided without diagnostic testing to individuals presenting with STI-associated symptoms such as genital discharge. Syndromic management is a relatively cheap approach that is easy to implement but also results in excessive and unnecessary use of antibiotics. Importantly, asymptomatic STIs remain untreated without diagnostic tests. A study from Cape Town showed that 91% of C. trachomatis and 67% of N. gonorrhoeae infections in MSM visiting sexual health services were asymptomatic, especially in the case of rectal infection.⁴ The higher frequency of asymptomatic manifestation of rectal infection in MSM is illustrated in the consistently higher rates of rectal than urethral infection in prevalence studies in South Africa.^{5,6,7,8,9,10,11}

To date, several studies have performed molecular STI testing of MSM in South Africa, but these are heterogeneous and have relatively small sample sizes. There are four studies on the aetiology of urethral and rectal discharge; six studies (including ours) report on the prevalence of C. trachomatis and N. gonorrhoeae in asymptomatic MSM, and only two studies have reported STI incidence data.^{4,5,6,7,8,9,10,11} The anatomic sites tested for STI also vary, while two studies only reported aggregated data. Additional data points, and a comprehensive overview of the burden of STIs in MSM in South Africa, are warranted.

We recently conducted a pilot randomised-controlled clinical trial of a skills-based HIV serostatus coping and disclosure management intervention for MSM in the Buffalo City Metropolitan Municipality in East London.¹² Participating MSM were also tested for C. trachomatis and N. gonorrhoeae at their baseline and follow-up visits, providing the opportunity to document the burden of STIs in this population. Therefore, we report on the incidence and prevalence of C. trachomatis and N. gonorrhoeae in MSM living with HIV infection in our pilot trial.

The mean age was 30 years in the intervention arm, and 33 years in the control arm. Most participants were in some form of relationship, and the majority of participants had been tested for an STI in the last year. Nearly all participants identified as homosexual or gay (Table 1).

At enrolment, 79.1% in the intervention arm had an undetectable HIV viral load (≤ 200 copies/mL), and 80% in the control arm. Syphilis rapid diagnostic test was positive in 9.3% of the intervention arm, and 2.3% of the control arm. Treponemal antibodies were confirmed by laboratory testing and all rapid plasma reagin (RPR) tests were positive, with titres of less than 1:8.

At baseline, 82 (93.2%) had a urethral C. trachomatis infection; 81 (92.0%) had a urethral N. gonorrhoeae infection; 75 (85.2%) had a rectal C. trachomatis infection; and 80 (90.9%) had a rectal N. gonorrhoeae infection (Figure 1). At week 17, 12 (27.9%) in the intervention arm had an STI, and 13 (28.9%) in the control arm. Univariable analyses did not identify factors that were associated with any STI at week 17 (Figure 2).

Median time of follow-up was 140 days (20 weeks; range 80–304 days). Incidence of any STI was 72 per 100 person-years (95% confidence interval [CI] 50–101), with incidence of 48 per 100 person-years (95%CI 30–73) for urethral infection, and 45 per 100 person-years (95%CI 28–70) for rectal infection (Table 2).

This study adds important information on the epidemic profile of STIs among MSM living with HIV in South Africa. Our findings demonstrate a high prevalence and incidence of C. trachomatis and N. gonorrhoeae infections, particularly at rectal sites, consistent with previous studies.^1,2,5,6,7,9 Notably, 29% of participants had an asymptomatic STI at baseline, increasing to 33% at follow-up, with rectal infections more common than urethral infections. Diagnostic STI screening may provide a tool to address this burden of infection, but important implementation questions have to be addressed, including the optimal frequency of screening and the uncertain impact on population prevalence and antimicrobial resistance.

The incidence rates observed are among the highest reported in South African MSM cohorts. These observations highlight the need for strengthening STI prevention, diagnosis and treatment services, and the implementation of innovative interventions. Doxycycline post-exposure prophylaxis (DoxyPEP) may provide such an option with strong reduction in STIs reported in clinical trials as well as STI programmes, particularly for chlamydia and syphilis.^15,16,17

Previous studies on C. trachomatis and N. gonorrhoeae from South Africa have found that urethral and rectal infections are prevalent, independent of asymptomatic infection.^5,6,7,9,10 Our study underscores the importance of STI prevention approaches, such as DoxyPEP. Moreover, our study demonstrates a modest reduction in any STI infection among the intervention arm, which suggests the importance of upscaling the SOAR intervention for this population throughout South Africa.

Asymptomatic STIs are highly prevalent and incident among MSM living with HIV in South Africa, with rectal infections predominating. Tailored interventions are essential to reduce transmission, improve sexual health outcomes, and align STI management with global best practices.