High HIV-1 incidence, correlates of HIV-1 acquisition, and high viral loads following seroconversion among MSM

Abstract

Background: HIV-1 incidence estimates and correlates of HIV-1 acquisition in African MSM are largely unknown.

Methods: Since 2005, HIV-1-uninfected men who reported sex with men and women (MSMW) or sex with men exclusively (MSME) were followed at scheduled visits for collection of behavioural and clinical examination data and plasma for HIV-1 testing. Urethral or rectal secretions were collected from symptomatic men to screen for gonorrhoea. Poisson regression methods were used to estimate adjusted incidence rate ratios to explore associations between risk factors and incident HIV-1 infection. Plasma viral loads (PVLs) were assessed over 2 years following seroconversion.

Results: Overall HIV-1 incidence in 449 men was 8.6 [95% confidence interval (CI) 6.7-11.0] per 100 person-years. Incidence was 5.8 (95% CI 4.2-7.9) per 100 person-years among MSMW, and 35.2 (95% CI 23.8-52.1) per 100 person-years among MSME. Unprotected sex, receptive anal intercourse, exclusive sex with men, group sex, and gonorrhoea in the past 6 months were strongly associated with HIV-1 acquisition, adjusted for confounders. PVL in seroconverters was more than 4 log10 copies/ml at 230 (73.4%) of 313 visits in MSMW and 153 (75.0%) of 204 visits in MSME.

Conclusion: HIV-1 incidence is very high among MSM in coastal Kenya, and many seroconverters maintain high PVL for up to 2 years after infection. Effective HIV-1 prevention interventions, including treatment as prevention, are urgently needed in this population.

Figure 1

Cumulative probability of HIV-1 acquisition in men who have sex with men exclusively (MSME) and men who have sex with men and women (MSMW) by year since cohort enrolment, Coastal Kenya, 2005–2011.

Figure 2

Figure 2a. HIV-1 plasma viral load (PVL) dynamics in 63 Kenyan seroconverters. In the first two years (104 weeks) after infection, PVL measurements are presented for men who have sex with men exclusively (MSME= filled circle) and men who have sex with men and women (MSMW = open circle). All visits with PVL (N = 517) are shown. Visits with high PVL (>4.0 log10) are above the horizontal line. Solid and dotted curves correspond to mean predicted PVL and 95% boundaries for MSME (204 person-visits) and MSMW (313 person-visits), respectively. Figure 2b. CD4+ T-cell (CD4) counts in 63 Kenyan seroconverters. In the first two years (104 weeks) after infection, CD4 counts are presented for MSME (filled circle) and MSMW (open circle). Among all visits (N = 504) shown, those with low CD4 count (<350 cells/mL) (n = 66 or 13.1%) are below the horizontal line. Solid and dotted trajectories correspond to mean predicted CD4 count and 95% boundaries for MSME and MSMW, respectively.

Figure 2

Figure 2a. HIV-1 plasma viral load (PVL) dynamics in 63 Kenyan seroconverters. In the first two years (104 weeks) after infection, PVL measurements are presented for men who have sex with men exclusively (MSME= filled circle) and men who have sex with men and women (MSMW = open circle). All visits with PVL (N = 517) are shown. Visits with high PVL (>4.0 log10) are above the horizontal line. Solid and dotted curves correspond to mean predicted PVL and 95% boundaries for MSME (204 person-visits) and MSMW (313 person-visits), respectively. Figure 2b. CD4+ T-cell (CD4) counts in 63 Kenyan seroconverters. In the first two years (104 weeks) after infection, CD4 counts are presented for MSME (filled circle) and MSMW (open circle). Among all visits (N = 504) shown, those with low CD4 count (<350 cells/mL) (n = 66 or 13.1%) are below the horizontal line. Solid and dotted trajectories correspond to mean predicted CD4 count and 95% boundaries for MSME and MSMW, respectively.