Vertical Transmission of Hepatitis C Virus
Source: Resti M, et al. Mother to child transmission of hepatitis C virus: Prospective study of risk factors and timing of infection in children born to women seronegative for HIV-1. Brit Med J 1998;317:437-441.
Resti and associates from the department of Pediatrics in Florence, Italy, followed 403 babies whose mothers had antibodies against hepatitis C but not HIV-1. The babies were followed for a median of 28 months (range 24-38 months). Blood samples from the mothers were tested for antibodies against hepatitis C by radio-immune assay and for hepatitis C virus RNA by the polymerase chain reaction. These tests were repeated on the mother at the time of delivery. The infants were tested with the same tests at birth, or as soon as possible after birth, and then at least three times during the 28-month average follow-up. Children were considered to be infected with hepatitis C if hepatitis C virus (positive PCR) was detected or when antibody persisted beyond 2 years of age or reappeared after having initially disappeared.
Hepatitis C viral RNA was found in 275 of 403 (68%) of antibody-positive mothers. As expected, all 403 babies were positive for transplacental hepatitis C antibody at birth. Hepatitis C viral RNA was found in 275 of 403 (68%) of antibody-positive mothers. Thirteen of 403 (3.2%) children had acquired hepatitis C infection by the end of the follow-up period. All of these infected children were born of one of the 275 mothers who were positive for hepatitis C virus. The risk of transmission in this group was 13/275, or 4.7%. None of the children born of the 128 mothers who were negative for hepatitis C viral RNA developed hepatitis C infection.
Resti et al conclude that in women who have been infected with hepatitis C, only those with hepatitis C virus RNA in their blood are at risk for infecting their infants. The risk of infection was not influenced by the mode of delivery (vaginal vs caesarian). Resti et al believe that transmission occurs in utero. Even though hepatitis C viral RNA can be demonstrated in breast milk, Resti et al do not believe that breast feeding is a risk factor, but they admit that their numbers are small. The rate of transmission is higher in women who had received blood transfusions or used intravenous drugs than in women who had no risk factors.
It is of some interest that the 3.2% risk of vertical transmission of hepatitis C by antibody-positive mothers is considerably lower than the 28% transmission of HIV-1 reported in HIV-positive mothers. —RAE