Acute maternal HIV infection during pregnancy and breast-feeding: substantial risk to infants.

We know, in theory and increasingly in practice, how to dramatically reduce rates of mother-to-child transmission (MTCT) of human immunodeficiency virus (HIV) type 1 (HIV-1). Specifically, perinatal transmission of HIV-1 can be lowered from 40% [1, 2] to !2% [3] with the use of a combination of antiretroviral drugs during pregnancy and labor (with or without cesarean section); brief infant prophylaxis with antiretroviral agents; and avoidance of breast-feeding. However , this reduction can be achieved only when we are aware of the presence of maternal HIV-1 infection and are able to intervene. The Joint United Nations Programme on HIV/AIDS estimated that, in 2007, only 1 in 3 HIV-infected pregnant women worldwide received any intervention to prevent MTCT [4]. Implementation of MTCT prevention interventions has been hindered by a multitude of factors globally, including limited or late access to antenatal care and to maternal HIV and CD4 testing; scarcity of trained health care workers to administer testing and treatment ; cost of and adherence to antiret-roviral drugs; and concerns regarding the safety, cost, and acceptability of replacement feeding. In this editorial commentary , we focus on one particularly formidable challenge to MTCT prevention efforts—one that has largely been overlooked: maternal HIV-1 acquisition during pregnancy or breast-feeding. This issue of the Journal includes an interesting and important report by Liang et al [5] that describes a very high rate of breast-feeding–related MTCT of HIV-1 in association with postpartum acute maternal HIV-1 infection. The authors identified 104 women in China who were infected with HIV-1 between 1994 and 2000—almost certainly through early postpartum receipt of infected blood products—and who exclusively breast-fed their children for some period without any intervention for the prevention of MTCT. Of the 106 children born to these mothers, 36 (35.8%) were infected with HIV-1. Among women who are chronically infected with HIV and who breast-feed for 18–24 months, one would expect that approximately 9%–16% of their children would become infected through breast-feeding [2, 6]. The rate of breast-feeding–related MTCT observed in the study by Liang et al is notably higher than such estimates noted among chronically infected women, but it is consistent with previously reported rates of breast-feeding–related MTCT among women who experienced seroconversion postpartum (see below). Primary HIV-1 infection is associated with very high levels of HIV-1 RNA [7, 8]. In turn, the maternal plasma HIV-1 RNA level is one of the most important predictors of perinatal HIV-1 …