Correlates of mother-to-child human immunodeficiency virus type 1 (HIV-1) transmission: Association with maternal plasma HIV-1 RNA load, genital HIV-1 DNA shedding, and breast infections

To determine the effects of plasma, genital, and breast milk human immunode ficiency virus type 1 (HIV-1) and breast infections on perinatal HIV-1 tran smission, a nested case-control study was conducted within a randomized cli nical trial of breast-feeding and formula feeding among HIV-1-seropositive mothers in Nairobi, Kenya. In analyses comparing 92 infected infants with 1 87 infants who were uninfected at 2 years, maternal viral RNA levels >43,00 0 copies/mL (cohort median) were associated with a 4-fold increase in risk of transmission (95% confidence interval [CI], 2.2-7.2). Maternal cervical HIV-1 DNA (odds ratio [OR], 2.4; 95% CI, 1.3-4.4), vaginal HIV-1 DNA (OR, 2 .3; 95% CI, 1.1-4.7), and cervical or vaginal ulcers (OR, 2.7; 95% CI, 1.2- 5.8) were significantly associated with infant infection, independent of pl asma virus load. Breast-feeding (OR, 1.7; 95% CI, 1.0-2.9) and mastitis (re lative risk [RR], 3.9; 95% CI, 1.2-12.7) were associated with increased tra nsmission overall, and mastitis (RR, 21.8; 95% CI, 2.3-211.0) and breast ab scess (RR, 51.6; 95% CI, 4.7-571.0) were associated with late transmission (occurring >2 months postpartum). Use of methods that decrease infant expos ure to HIV-1 in maternal genital secretions or breast milk may enhance curr ently recommended perinatal HIV-1 interventions.