Vertical transmission of hepatitis C virus (HCV) detected by HCV-RNA analysis

Influence of maternal human immunodeficiency virus (HIV) co-infection on vertical transmission of hepatitis C virus (HCV): a meta-analysis

BACKGROUND

Maternal co-infection with human immunodeficiency virus (HIV) has been implicated as a potentially important co-factor for enhanced vertical transmission of hepatitis C virus (HCV). In previous reports, however, methodological issues (notably small sample sizes) have limited accurate evaluation of the contribution of maternal co-infection with HIV on the risk of vertical transmission of HCV.

METHODS

A systematic review and subsequent meta-analysis of current published and unpublished reports was performed. Odds ratios (OR) and 95% CI for individual studies were calculated with maternal HIV serostatus as the exposure measure and HCV vertical transmission as the outcome measure. Overall summary estimates were then calculated using a random effects model that estimates a weighted average of OR from individual studies.

RESULTS

In total, 2382 infants from 10 studies were included in an analysis of HCV-infected mothers (defined by anti-HCV+ antibody assays) with and without concomitant HIV infection. The risk estimate (OR) of HCV vertical transmission was 2.82 (95% CI: 1.78-4.45; P = 0.00001) from anti-HCV+/HIV+ co-infected mothers compared with anti-HCV+/HIV- mothers. In a subanalysis of 1327 infants born to viraemic (HCV RNA+) mothers, the risk estimate of HCV vertical transmission was 1.97 (95% CI: 1.04-3.74; P = 0.04) from HCV viraemic/HIV+ co-infected mothers compared with HCV viraemic/HIV- mothers.

CONCLUSIONS

Results from this meta-analysis of observational studies suggest that the risk of HCV vertical transmission is higher in infants born to HIV co-infected mothers.

Hepatitis C: an epidemiological review

The aim of the study was to analyse the current literature regarding the mode of transmission of HCV and its global prevalence in different groups of people. A systematic review of the literature on the epidemiology of hepatitis C from 1991 to 2000 using computerized bibliographic databases which include Medline, Current Content and Embase. The prevalence of hepatitis C virus (HCV) varies tremendously in different parts of the world, with the highest incidence in the Eastern parts of the globe compared with the Western parts. Furthermore, certain groups of individuals such as intravenous drug users are at increased risk of acquiring this disease irrespective of the geographical location. Although the main route of transmission is via contaminated blood, curiously enough in up to 50% of the cases no recognizable transmission factor/route could be identified. Therefore, a number of other routes of transmission such as sexual or household exposure to infected contacts have been investigated with conflicting results. Hepatitis C infection is an important public health issue globally. Better understanding of routes of transmission will help to combat the spread of disease. In order to prevent a world wide epidemic of this disease, urgent measures are required to (i) develop a strategy to inform and educate the public regarding this disease and (ii) expedite the efforts to develop a vaccine.

[Breastfeeding and hepatitis C virus (HCV): the need for a careful appraisal]

We review the available data on the possible role of breast-feeding in hepatitis C virus (HCV) transmission to infants of HCV-RNA-positive mothers. Current knowledge about HCV excretion through breast milk, HCV infection of breast-fed infants by mothers contaminated after delivery, and vertical transmission risk to infants breast-fed by chronic HCV viremic mothers are presented. Vertical transmission risk by breast-feeding HCV-RNA-positive mothers is unclear: no study has been performed with the aim and the required methodology to evaluate HCV transmission risk related to breast-feeding duration. Recommendations to HCV-RNA-positive mothers who wish to breast-feed their infant are discussed in light of present knowledge about HCV secretion in breast milk, mother-to-infant HCV transmission, and historical records on vertical transmission of other viruses to infants breast-fed by their viremic mothers.

Hepatitis C--role of perinatal transmission

To evaluate the role of perinatal transmission in the spread of hepatitis C virus (HCV), we screened a cohort of pregnant intravenous drug using (IVDU) women for HCV antibody detection; where seropositive HCV RNA detection by polymerase chain reaction (PCR) was found we followed the infants longitudinally for HCV antibody and HCV RNA. Serum prevalence for HCV for this population was 80% with HCV RNA detected in 50%. Recruitment and follow-up over a 3-year period of a cohort of 83 seropositive women, their 91 newborns and 16 siblings of newborns, showed that there had been a 3% perinatal transmission rate with 1 sibling also infected. These positive cases were defined as transient in 1 case (HCV RNA positive by PCR at 1 month, but seronegative and HCV RNA negative at 10 months of age), 2 unevaluable (HCV RNA positive at 2 months of age, but patients lost to follow-up), and 1 chronic infection in a child at 34 months (positive HCV RNA and seropositive 34-month sibling). Maternal HCV RNA levels for those with infected infants was a mean 40-fold greater than those whose babies were uninfected, although this did not reach statistical significance. Of the remaining infants, the majority (93%) had lost passively acquired maternal antibodies by 9 months of age and all by 12 months. Of 18 women who were HCV seropositive and breast feeding (66% of whom were HCV RNA positive in their sera), none had detectable HCV RNA in breast milk. Hence we conclude that transmission of HCV from mother to infant appears to be of low frequency and positivity appears to correlate with maternal circulating viral load.

[Rationale for a trial of prevention of perinatal transmission of hepatitis C via specific immunoglobulins]

Vertical transmission of the HCV infection is asymptomatic, occurring in 0-25% of infants born to viremic mothers in Europe. Nowadays, the only preventive measure in to advise against breastfeeding. Favourable conditions for a seroprophylaxis trial in neonates at risk are the low viral charge and the absence of former replication or integration. Several impediments to a randomized-controlled trial should be considered: Epidemiological: paucity of recruitment; low risk of transmission; possible antenatal transmission in cases of high maternal viremia; risk for intrafamilial transmission. Methodological: complex randomization of the study groups (genotyping, quantitative PCR, activity of mothers' diseases, modes/durations of delivery and feeding). Ethical: a direct individual benefit is not clearly established; should viremic mothers be allowed to breast feed their babies in the absence of prophylaxis? the risk of the emergence of mutants or quasi-species of the transmitted hepatitis C virus in neonates; the origin and selection of seropositive plasma donors.

Interferon-alpha for viral hepatitis

IFN-alpha has emerged as a promising treatment of chronic viral hepatitis. Although therapeutic response to IFN is far from universal, efficacy has been demonstrated; and studies combining IFN-alpha with other agents, as well as trials with new preparations of IFN-alpha, are under way. Children do not represent a large part of the identified population with chronic viral hepatitis. Yet children, by simple virtue of age, are more recently infected. In addition, longer life expectancies can be expected to be associated with greater morbidity from chronic viral hepatitis. Children seem to tolerate therapy with IFN-alpha well. Treatment of children with chronic viral hepatitis should be strongly considered, with protocols designed to ascertain specific pediatric safety and efficacy.

Hepatitis C virus infection: clinical aspects and treatment with interferon alfa

Screening for antibodies to hepatitis C virus (HCV) has substantially reduced the risk of HCV infection from transfusion of blood and blood products. Nevertheless, new infections may continue to occur. These infections may be caused by donor infections that escape detection or by insufficient decontamination of blood products during preparation. Frequently, HCV infection becomes chronic, is clinically silent, and can be associated with extrahepatic illnesses and liver cancer. A recent outbreak of HCV infection in patients who received intravenous immunoglobulin has permitted study of this infection in immunocompromised hosts. Some evidence indicates that this infection is more virulent in these patients, and our experience at Children's Hospital, Boston, Massachusetts, substantiates this finding. In this article, epidemiology and modes of transmission of HCV, pathogenesis of HCV infections, differential diagnosis, and clinical features of HCV infection in both children and adults are discussed. Particular attention is given to the serologic findings seen in the spectrum of diseases associated with chronic HCV infection. The mechanisms of action of interferon alfa treatment of HCV infections are discussed. However, results of interferon alfa treatment of patients with HCV infection at Children's Hospital are preliminary.

Vertical transmission of hepatitis C virus infection

Since the virus responsible for non-A, non-B hepatitis was cloned in 1989, much has been learnt about the epidemiology, diagnosis and clinical spectrum of hepatitis C virus (HCV) infection. As the routes of transmission are elucidated, specific groups of children as well as adults are known to be at particular risk of infection. The women most at risk of HCV infection are those with a history of injecting drug use. Mother-to-child transmission has been documented, although the exact risk has not been quantified, and the factors influencing the risk remain to be evaluated. This article reviews current knowledge on vertical transmission of HCV, and provides some guidelines on the management of infants born to women infected with the virus.

Mother-to-infant transmission of hepatitis C virus: a prospective study

To investigate the risk of mother-to-infant transmission of hepatitis C virus (HCV) and the natural course of HCV-infected infants, we prospectively studied 31 offspring of pregnant women who were anti-HCV positive and anti-HIV negative. Sera were serially tested for anti-HCV by the second-generation ELISA-test (ELISA-2) and for HCV-RNA by the polymerase chain reaction procedure. The mean period of follow up was 19 months (range 6-41 months). The presence of HCV-RNA in the mothers was associated with a high titre of anti-HCV by ELISA-2 or a positivity of the second generation recombinant immunoblot assay. At birth, 26 babies were positive for anti-HCV. Passively transferred maternal antibodies became undetectable within 2-15 months. HCV-RNA was detected in only 3 infants (9.7%) within 1-4 weeks after birth and persisted thereafter. The genotype of HCV-RNA in each of the infants was consistent with that of their mother. These 3 showed chronic transaminase elevation during the follow up that started at 1-2 months of age, although they revealed no clinical symptoms. Reelevation of anti-HCV titre was observed in the HCV-infected infants within 10 months of age, suggesting an endogenous production of anti-HCV. The mean titre of HCV-RNA in three mothers of infected infants was higher than that in the mothers of uninfected infants (10(5.3 +/- 0.3) vs 10(4.4 +/- 0.2)/ml).

CONCLUSION

Our findings indicate that HCV was most likely to have been transmitted from mothers to infants at the time of delivery and that it was capable of evoking the chronic carrier state.

Molecular epidemiology of hepatitis C virus infection amongst intravenous drug users in rural communities

The prevalence of hepatitis C virus (HCV) infection amongst a group of intravenous drug users (IVDUs) resident in West Suffolk (East Anglia, England) was investigated and compared with the prevalence of infection with hepatitis B virus (HBV) and human immunodeficiency virus (HIV). In addition, both the level of HCV persistence, as defined by detection of viral RNA, and the HCV genotypes present in this population were determined. It was found that HCV antibodies were present in 59% of those tested; by comparison 22% had antibodies to HBV and 1% antibodies to HIV. HCV RNA was found in 44% of those with HCV antibody. HCV genotype 1 was the most prevalent within this population although both genotypes 2 and 3 were also represented.

Mother-to-infant transmission of hepatitis C virus

Anti-hepatitis C virus (HCV) antibodies and HCV-RNA were measured in the sera of 22 anti-HCV positive, HIV-1 negative mothers and their infants. ELISA and RIBA II were used for anti-HCV determination. HCV-RNA was measured by a nested polymerase chain reaction. HCV-RNA was found in 12 of 22 mothers. All 22 children were followed for 12 months. All were anti-HCV positive by the fourth month; 18 became anti-HCV negative between the 8th and 12th month. HCV-RNA was detected in 5 of 22 infants in the fourth month. They remained HCV-RNA positive. All children born to HCV-RNA negative mothers were HCV-RNA negative while 5 of 12 babies born to HCV-RNA positive mothers were infected. All five infected babies were born to mothers infected through transfusions or drug use. ALT levels in mothers seemed to have no effect on mother-to-infant transmission. Hence evidence for perinatal transmission of HCV from HCV-RNA positive mothers was demonstrated in the present study.

Transmission of hepatitis C virus from mothers to infants: its frequency and risk factors revisited

A total of 16,714 pregnant Japanese women were tested for antibodies against hepatitis C virus (HCV), and 163 (0.98%) were positive. None of these were infected with human immunodeficiency virus-1 (HIV-1). We conducted a prospective study to discover the rate of HCV infection in babies born to mothers who were HCV RNA-positive but had no evidence for hepatitis (so called "asymptomatic carriers"), and only 2 (2.3%) of 87 such babies became infected during follow-up. This rate was considerably lower than those from other reports which included mothers with clinically overt chronic hepatitis C. We conducted another study to follow babies born to mothers with chronic hepatitis C, and found two babies infected. All of the four infected babies were born to mothers who had HCV RNA in their circulations around delivery at high titers (greater than 5.0 x 10(6) Eq/ml by branched DNA assay). This confirmed the previous finding that virus load was an important risk factor. In addition, we found three families where mother-to-infant HCV transmission was suspected in a retrospective study by indexing HCV-infected pediatric patients. Throughout the seven families, siblings of infected babies were free from HCV infection, suggesting that maternal infection of HCV owes much to chance. Breast milk feeding was not regarded as a risk factor. We also assessed the prevalence of anti-HCV antibody among 6-year old children, and only 10 of 10,446 (0.1%) were positive, suggesting low frequency of HCV infection during the period from birth to this age.