Maternal viral load and hepatitis C virus vertical transmission.

Abstract

To the Editors: Recently published studies state that the HCV transmission rate is not influenced by delivery mode and breast-feeding (1); on the contrary, some authors report that maternal plasma HCV viral load (VL) may play an important role (2). Because HCV is transmitted mainly in the neonatal period, women with higher VL may be at higher risk for transmitting HCV infection to their infants (either during vaginal delivery or during breastfeeding); the virus amount in vaginal secretion and in human milk seems to depend on maternal VL (3). To better understand the meaning of VL in HCV vertical transmission, we report some recent data gathered at our Paediatric Department concerning HIV–HCV co-infected women. A higher risk of transmitting HCV has been associated with a higher HCV plasma VL in HIV–HCV co-infected women; furthermore, lower HIV-1 VL and higher CD4+ T lymphocyte values are associated with a significant reduction in HCV vertical transmission rate (4). These findings are probably related to the immunodeficiency caused by HIV infection. From June 1999 until June 2002, 25 HIV–HCV co-infected women delivered in San Paolo Hospital in Milan. The women were HCV–RNA positive; antiretroviral therapy (ART) was administered during pregnancy and at labor following current guidelines (1 drug in 6 women, 2 in 8 women, 3 in 11 women) (4). All women underwent caesarean section and their infants were formula fed. All infants were evaluated for HCV–RNA at birth, after one month, and every three months thereafter. A child was considered HCV uninfected if two HCV-RNA consecutive detections were negative. None of the 25 mothers transmitted HCV infection to their infants. Before the introduction of ART for HIV infection during pregnancy and labor, HCV transmission rate in HIV–HCV co-infected women was 10% to 20% (5). Based upon this transmission rate, we would have expected 2 to 5 HCV-infected infants to be born from the 25 HIV–HCV positive mothers (probability range to find 0 infected infants: 0.004–0.072). The absence of HCV transmission in our mother–infant pairs could be attributed to ART; HIV therapy could have improved the mother's immune response by reducing HIV VL and this could explain a secondary HCV viral burden reduction. If our data is confirmed by larger studies, ART could represent a fundamental intervention in reducing and/or eliminating HCV vertical transmission for HIV–HCV co-infected mothers. Otherwise, it is necessary to identify a different preventive strategy for mothers who are infected only with HCV, carrying a high HCV plasma VL. For these patients, caesarean section and formula feeding could be considered as possible preventive measures. Zuccotti Gian Vincenzo Salvini Filippo Gemmellaro Laura Giovannini Marcello