Exposure to HIV-1 during delivery and mother-to-child transmission

Background: The correlation between the presence of HIV-1 in maternal cervi covaginal secretions and in the infant's ore-pharyngal secretions at birth, and mother-to-child HIV transmission (MTCT) were examined to obtain a bett er understanding of its mechanism. Methods: Women without medical and obstetrical complications, living within a reasonable distance of the government hospital in Mombasa, Kenya, were r ecruited after informed consent. Maternal and infant characteristics were c ollected. Polymerase chain reaction was used to detect HIV-1 in cervico-vag inal and ore-pharyngal secretions. Infants were tested for HIV-1 by polymer ase chain reaction within 48 h and at 6 weeks after delivery. Results: Between April 1998 and April 1999, 228 woman-infant pairs were inc luded in the study. HIV-1 DNA in cervico-vaginal secretions was independent ly associated with HIV-1 maternal viral load and with infant birth-weight, whereas HIV-1 RNA was associated with maternal viral load and maternal age. HIV-1 DNA in the oropharyngal secretions was also independently associated with maternal viral load. MTCT rate at the age of 6 weeks was 23.6%. Intra partum and early postpartum HIV transmission was independently associated w ith maternal viral load [adjusted odds ratio (OR), 1.6; 95% confidence inte rval (CI),1.0-2.7], detection of HIV-1 RNA in cervico-vaginal secretions (a djusted OR, 3.2; 95% CI, 1.5-7.3) and of HIV-1 DNA in ore-pharyngal secreti ons (adjusted OR, 3.2; 95% CI, 1.1-9.0). Discussion: As far as is known, this is the first study showing that infant exposure to HIV-1 in the birth canal and the presence of HIV-infected cell s in the infant's oropharyngal cavity are independently associated with int rapartum and early postpartum MTCT. It supports the hypothesis that MTCT co uld occur through the oral route. (C) 2000 Lippincott Williams & Wilkins.