Incident Gonorrhoea and Chlamydia Among a Prospective Cohort of Men Who Have Sex with Men in Kisumu, Kenya

Objective: STIs disproportionately affect men who have sex with men (MSM) in sub-Saharan Africa. We identified factors associated with incident (CT) and (NG) infections among MSM in the Anza Mapema cohort study in Kisumu, Kenya.

Methods: We enrolled 711 MSM who underwent HIV testing and counselling, medical history and examination, and collection of demographic and behavioural information. They also provided urine and rectal swab specimens for CT and NG testing by qualitative PCR at baseline and at months 6 and 12. Separate multivariable Cox regression models identified factors associated with first incident urethral or rectal infection.

Results: Among the 619 men aged 18-54 years included in this analysis, there were 83 first incident urethral CT/NG infections (14.4 cases per 100 person-years (PY)) and 40 first incident rectal infections (6.84 cases per 100 PY), and an overall incidence of 18.0 cases per 100 PY (95% CI 14.8 to 21.8). Most urethral (84%) and rectal (81%) infections were asymptomatic. In the adjusted model, the risk of first incident urethral CT/NG decreased by 4% for each 1-year increase in age and was 41% lower for men who reported their partner used condom at last sexual encounter. Men who were HIV-positive had a 68% less risk of urogenital CT/NG compared with those who were negative. Men who reported being usually receptive or versatile as compared with usually insertive had an 81% increased risk of incident urogenital CT/NG.

Conclusion: Our study demonstrated a high incidence of urethral CT/NG infection, with somewhat lower incidence of rectal CT/NG infection, despite repeated testing and treatment, highlighting the need for preventive interventions to decrease the burden of CT/NG among Kenyan MSM. Most infections were asymptomatic, and routine aetiological screening for STIs is recommended.