Abstract:
Objectives: To assess the prevalence, incidence and factors associated with Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infection among HIV-negative men who have sex with men (MSM) and transgender women (TGW) in Kenya.
Design: Prospective cohort.
Setting: Kisumu, Nairobi and coastal Kenya.
Participants: 650 young adult participants (570 MSM and 80 TGW) recruited at three research clinics. Inclusion criteria were HIV-negative status, age 18-29 years, assigned male sex at birth, identification as cisgender male or transgender female and reported anal intercourse with a man in the past 3 months.
Primary and secondary outcome measures: Urine, rectal and oropharyngeal samples were tested for CT/NG infection at two different time points (∼6 months apart), using nucleic acid amplification. We compared CT/NG prevalence and incidence in MSM versus TGW and used Poisson regression to compare risk for each group after adjustment for other correlates of prevalent and incident CT/NG infection.
Results: Prevalence of CT/NG infection at any anatomic site was 15.8% and 27.5% in MSM and TGW, respectively (p=0.009). CT/NG incidence was 27.2 (95% CI 21.3 to 34.7) and 24.5 (95% CI 12.3 to 49.0) per 100 person years for MSM and TGW, respectively (p=0.784). In multivariable analysis, there was no difference in prevalence or incidence by gender identity. Baseline CT/NG infection was more prevalent among TGW (adjusted prevalence ratio 1.61, 95% CI 0.99 to 2.62). Incident CT/NG infection was increased among participants with baseline CT/NG infection (adjusted incidence rate ratio (aIRR) 3.14, 95% CI 1.94 to 5.07) and self-reported pre-exposure prophylaxis use (aIRR 1.75, 95% CI 1.04 to 2.93).
Conclusion: Despite higher prevalence of CT/NG infections among TGW at baseline, there were no differences in CT/NG prevalence and incidence between TGW and MSM, after adjustment for potential confounders. Improved condom use, effective partner notification and treatment, and new strategies such as doxycycline post-exposure prophylaxis are needed to reduce CT/NG infections in both MSM and TGW in settings where regular testing is not possible.