Horizontal versus vertical transmission of human immunodeficiency virus type 1 (HIV-1). Experience from southwestern Saudi Arabia.

Twenty-five confirmed cases of human immunodeficiency virus type 1 (HIV-1) infection due to blood transfusion have been documented at King Fahad Hospital (KFH) in Al-Baha, southwestern Saudi Arabia since 1986, but complete follow-up was only possible on 19 of these cases and their contacts. Seventeen cases were diagnosed as having acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) after admission to the hospital due to the deterioration of their health status. Two cases were found to be anti-HIV-1 positive on routine screening for blood donation. This cluster of HIV-1 infected patients through blood transfusion allowed us to study the efficiency of sexual transmission of HIV-1 infection between spouses, the rate of perinatal transmission of HIV-1 infection, and to see whether intrafamilial transmission is a possible route of spread of the virus. Firstly, the present results confirm our earlier observation that transmission of HIV-1 infection was more efficient from the infected husband to his wife(s) in contrast to the inefficient transmission of the infection from the infected wife to her husband. Secondly, by the age of 16 months, all nine newborns to HIV-1 infected mothers became HIV-1 infected. This highlights the importance of medical advice to those mothers regarding conception and/or breast-feeding, particularly as breast-feeding up to 2 years is not an uncommon practice among Saudi women. Finally, none of the household contacts of the 19 cases was infected until now, indicating that intrafamilial spread of HIV-1 did not occur among the population studied.