Longitudinal analysis of human immunodeficiency virus type 1 RNA in breast milk and of its relationship to infant infection and maternal disease

Abstract

Transmission of human immunodeficiency virus type 1 (HIV-1) via breast-feeding can occur throughout lactation. Defining both fluctuation in breast-milk virus level over time and how breast-milk virus correlates with mother-to-child transmission is important for establishing effective interventions. We quantified breast-milk HIV-1 RNA levels in serial samples collected from 275 women for up to 2 years after delivery. Higher maternal plasma virus load, lower maternal CD4 T cell count, and detection of HIV-1 DNA in maternal genital secretions were significantly associated with elevated breast-milk HIV-1 RNA. Within women who breast-fed, median virus load in colostrum/early milk was significantly higher than that in mature breast milk collected 14 days after delivery (P< or =.004). Breast-feeding mothers who transmitted HIV-1 to their infants had both significantly higher breast-milk viral RNA throughout lactation and more-consistent viral shedding, compared with mothers who did not transmit HIV-1. In breast-feeding women, a 2-fold-increased risk of transmission was associated with every 10-fold increase in breast-milk virus load (95% confidence interval, 1.3-3.0; P<.001). These results indicate that the risk of infant infection from breast-feeding is influenced by breast-milk virus load, which is highest early after delivery.

Figures

Figure 1

First-breast-milk load of human immunodeficiency virus type 1 (HIV-1)—and incidence of mother-to-child transmission.

Figure 2

Breast-milk load of human immunodeficiency virus type 1 (HIV-1) over time, in all transmitting mothers (white bars) and nontransmitting mothers (black bars) who breast-fed their infants, with P values for comparisons of the 2 groups; for the 7 sampling times indicated, the no. of transmitting mothers was 32, 36, 31, 23, 13, 9, 6, respectively, and the no. of nontransmitting mothers was 73, 80, 74, 58, 37, 25, 13, respectively.

Figure 3

Correlation between breast-milk virus load in human immunodeficiency virus type 1 (HIV-1) and both maternal plasma virus load and maternal CD4 T cell count.