Clear evidence exists documenting the perinatal vertical transmission of hepatitis C virus (HCV) infection. Maternal coinfection with HCV and human immunodeficiency virus (HIV) has been correlated with the probability of perinatal infection. The rate of vertical transmission of HCV appears to be low (ranging from zero to 6 percent). Bortolotti and associates conducted a multicenter study to investigate the features of hepatitis C infection in a group of infants who were born to mothers with hepatitis C antibodies and a group of children with chronic hepatitis C infection whose mothers were the only potential source of infection.

The first group included 14 infants who were seropositive for HCV who were born to mothers with hepatitis C antibodies and without HIV infection or hepatitis B surface antigen (HbsAg). The second group included 16 children with chronic HCV infection whose mothers had no HbsAg and who were chronic carriers of HCV. One mother had antibodies to HIV. The mothers were the only potential source of infection in this group. Both groups of children were followed for 12 to 48 months after birth.

All of the children in the first group had elevated alanine aminotransferase levels, ranging from 1.5 to 10.5 times normal during the first 12 months of life. RNA for HCV was detectable in all children at nine months of age and in some children as early as three months after birth.

All of the children in the second group came to observation after laboratory testing was performed because of intercurrent disease or after the detection of maternal antibodies to HCV. During a mean observation period of 18.7 months, alanine aminotransferase levels varied from normal to six times the upper limit of normal in these children, but exceeded twice the normal limit in only six children. RNA for HCV was detected in all of the children.

The authors conclude that HCV could have been vertically transmitted to the children even in the absence of a cofactor such as maternal HIV coinfection. These preliminary studies demonstrate that chronic infection acquired from mothers with HCV occurs in a high percentage of children, although liver disease appears to be asymptomatic during infancy and mild throughout childhood. Whether or not there is long-term recovery from HCV infection remains to be determined through longer follow-up studies.

In an accompanying editorial, Zein discusses the variability of vertical transmission of various genotypes of HCV and the lack of support for routine maternal screening. The failure to document transmission of HCV through breast feeding even in mothers whose breast milk showed RNA for HCV supports the likelihood of in utero vertical transmission of the virus. In the United States and Europe, the prevalence of HCV is approximately 1.2 percent of the general population. The incidence of vertical transmission is estimated to be up to 5 percent. The screening of 1,600 to 8,300 pregnant women would be needed for each case of vertical transmission diagnosed. The author concludes that since there is no specific means of intervention (i.e., either a vaccine or a successful treatment), routine screening for HCV cannot be performed at the present time.