Breastfeeding and the risk of vertical transmission of hepatitis C virus

Hepatitis B and C viruses in infants and young children

Advances during the past 20 years have led to a better understanding of the prevention, diagnosis, and treatment of acute and chronic hepatitis B (HBV) and hepatitis C (HCV) infections in the pediatric population. Universal vaccination and prenatal testing for HBV have decreased the incidence rate of acute HBV infections from more than 3/100,000 to 0.34/100,000 in all children. Diagnosis of chronic HBV is confirmed with positive serologic testing on two occasions at least 6 months apart. Current approved therapies with interferon alpha and lamivudine for children with chronic HBV infection have shown some efficacy, but results have been variable. In contrast, the lack of an effective HCV vaccine and the risk of mother-to-child transmission may increase the number of children with vertically acquired HCV that ultimately go on to develop liver fibrosis or cirrhosis. Diagnosis of HCV in the neonate should be postponed until after the child reaches 1 year of age because infants may have transient viremia. Treatment for HCV infected children has not been studied extensively. Peginterferon alpha-2a and Ribavirin are not currently approved for pediatric use; however, recent studies in children have shown potential benefit. More effective and less toxic therapies for young patients with HBV and HCV are needed, as are methods to interrupt perinatal transmission of HBV and HCV.

Low risk of vertical transmission of hepatitis C virus by breast milk

To evaluate the risk of hepatitis C virus (HCV) transmission via breast milk, we collected 76 samples of breast milk from 73 chronically HCV-infected women and serum samples from their 76 perinatally HCV-exposed children. Enzyme immunoassay and strip immunoblot assay were used for detection of antibodies to HCV, and reverse transcriptase-polymerase chain reaction analysis was used for detection of HCV RNA. None of the 76 samples of breast milk contained HCV RNA, whereas 37 (59.7%) of 62 mothers tested for HCV RNA had HCV viremia. Only 1 of the 76 breast-fed infants had evidence of HCV infection. Because HCV infection in this child was detected 1 month after birth, it seems unlikely that it was transmitted by breast-feeding. These results indicate that HCV infection in pregnant women should not be a contra-indication for breast-feeding.

Hepatitis C

Hepatitis C virus (HCV) infection afflicts millions of people in the United States and worldwide. We examine the epidemiology of HCV infection, the molecular biology of the virus, the pathophysiology of infection, the clinical diagnosis and manifestations of infection, and the treatment of HCV infection.

Use of polymerase chain reaction and antibody tests in the diagnosis of vertically transmitted hepatitis C virus infection

Data on patterns of polymerase chain reaction (PCR) and antibody test results in infants born to hepatitis C virus (HCV)-infected mothers were systematically reviewed to aid development of optimum testing schedules and diagnostic criteria for vertically exposed infants and to facilitate early identification of infected infants. Survival and cross-sectional analyses were used to estimate the timing of initial PCR positivity and subsequent PCR negativity in infected infants, and maternal antibody loss in uninfected infants was estimated as a weighted average of individual study findings. Of 74 eligible infants with strong evidence of HCV infection, an estimated 89% (90% confidence interval, 80-95%) were first PCR positive by 3 months of age, and less than 10% had subsequent PCR negativity attributable to intermittent viraemia or resolved infection in the first 18 months of life. The negative predictive value of PCR at 3 months of age was greater than 98% at an assumed rate of 5% vertical transmission, but as low as 88% at 25% transmission. The inclusion of 22 infants, each with a single PCR-positive result, increased the estimated frequency of resolved infections but made little difference to other estimates. A minority of PCR-positive infants had periods of antibody negativity by second- or third-generation assays, and among 297 uninfected infants, maternal antibody was not detected beyond 18 months. Thus, the majority of infected infants may be persistently PCR positive from 3 months of age, and the negative predictive value of PCR at 3 months is generally high. However, poor repeatability of PCR, inadequate infant follow-up, and inclusion of postnatally infected infants limits interpretation of the pooled data. Further studies using standardised PCR methodologies are needed.

Hepatitis C transmission on the north coast of New South Wales: explaining the unexplained

OBJECTIVE

To determine the routes of hepatitis C virus (HCV) transmission in an Australian community.

DESIGN

Questionnaire-based, cross-sectional survey of notified HCV cases.

SUBJECTS AND SETTING

All cases notified to the New South Wales North Coast Public Health Unit between 1 January 1993 and 30 September 1994.

OUTCOME MEASURES

Frequency of potential transmission exposures (parenteral and sexual); most likely primary exposure; HCV infection rates in sexual partners and offspring.

RESULTS

467 subjects responded (47% of resident cases). Of these, all but one reported actual or potential blood exposures (injecting drug user [IDU], 85%; IDU with sharing of injection equipment, 76%; pre-1990 blood transfusions, 6%; other blood exposures, 8%). Most subjects reported multiple exposures and none reported sexual contact as the only potential exposure. Of 233 sexual partners tested for HCV, 83 were positive; 54 of these were questioned and all had other parenteral exposures. Only three children out of 91 children tested were positive for HCV (two expressing maternal antibodies).

CONCLUSIONS

In contrast with previous studies, possible HCV transmission modes were identified for almost all respondents. Most respondents in this community were IDUs. Non-parenteral transmission appeared minimal. Novel approaches to preventing HCV transmission in IDUs are needed.

Hepatitis in the obstetric patient

The six agents identified thus far that cause viral hepatitis are reviewed, and their impact upon pregnancy is described. Although it is the most common cause of jaundice during pregnancy, viral hepatitis does not generally increase the risk of pregnancy complications, nor is it teratogenic. Vertical transmission of some types of viral hepatitis does occur, however.