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

Viruses and Human Milk: Transmission or Protection?

Human milk (HM) is considered the best source of nutrition for infant growth and health. This nourishment is unique and changes constantly during lactation to adapt to the physiological needs of the developing infant. It is also recognized as a potential route of transmission of some viral pathogens although the presence of a virus in HM rarely leads to a disease in an infant. This intriguing paradox can be explained by considering the intrinsic antiviral properties of HM. In this comprehensive and schematically presented review, we have described what viruses have been detected in HM so far and what their potential transmission risk through breastfeeding is. We have provided a description of all the antiviral compounds of HM, along with an analysis of their demonstrated and hypothesized mechanisms of action. Finally, we have also analyzed the impact of HM pasteurization and storage methods on the detection and transmission of viruses, and on the antiviral compounds of HM. We have highlighted that there is currently a deep knowledge on the potential transmission of viral pathogens through breastfeeding and on the antiviral properties of HM. The current evidence suggests that, in most cases, it is unnecessarily to deprive an infant of this high-quality nourishment and that the continuation of breastfeeding is in the best interest of the infant and the mother.

No. 96-The Reproductive Care of Women Living With Hepatitis C Infection

OBJECTIVE

hepatitis C virus (HCV) is an increasingly important public health problem worldwide. Health care workers providing care to women of childbearing age are uniquely placed in their practices to identify a significant proportion of at-risk patients and to provide appropriate screening and counselling. The primary objective of this guideline is to provide accurate, current information to those offering reproductive care to women living with HCV. This document is also intended to raise awareness of HCV in both the medical and general populations.

OPTIONS

the areas of clinical practice considered in formulating this guideline are disease prevention, targeted screening of individuals at risk of contracting HCV, management of identified patients in the context of reproductive care, and the appropriate referral of patients to those with particular expertise.

OUTCOMES

implementation of these guidelines should facilitate identification of infected individuals. It should also result in improved physical and mental well-being for patients and their families and reduction in transmission rates.

EVIDENCE

the literature between 1966 and 2000, including non- English language publications, was extensively searched utilizing Medline. A multidisciplinary group consisting of experts within the fields of obstetrics and gynaecology, infectious diseases, hepatology, and public health convened in Montreal in February 2000. The working group also included a patient and a representative from the Hepatitis C Society of Canada. The level of evidence for the recommendations has been determined using the criteria described by the Canadian Task Force on Periodic Health Examination.

BENEFITS, HARMS AND COSTS

the public health benefits of increased identification of at-risk individuals, diagnosis, treatment, implementation of risk reduction behaviours, and reduced transmission rates, both on an individual and at the community level, are significant. However, it must be remembered that the diagnosis of a chronic disease may have far reaching effects for the individual patient and her family.

RECOMMENDATIONS

VALIDATION: references were collected through Medline searches and comparison made to existing current guidelines for assessment of consistency. External reviewers expert in their field were also consulted.

Hepatitis C in Pregnancy: A Unique Opportunity to Improve the Hepatitis C Cascade of Care

Hepatitis C has increasingly affected women of child-bearing age over the past few years as a result of the opioid epidemic. In this review, we discuss the effect of hepatitis C on pregnancy outcomes, effect of pregnancy on hepatitis C, as well as implications on management of hepatitis C during pregnancy.

THE EVOLUTION OF VIRULENCE IN PATHOGENS WITH VERTICAL AND HORIZONTAL TRANSMISSION

The idea that vertical transmission of parasites selects for lower virulence is widely accepted. However, little theoretical work has considered the evolution of virulence for parasites with mixed horizontal plus vertical transmission. Many human, animal, and plant parasites are transmitted both vertically and horizontally, and some horizontal transmission is generally necessary to maintain parasites at all. We present a population-dynamical model for the evolution of virulence when both vertical and horizontal transmission are present. In the simplest such model, up to two infectious strains can coexist within one host population. Virulent, vertically transmitted pathogens can persist in a population when they provide protection against more virulent, horizontally transmitted strains. When virulence is maintained by a correlation with horizontal transmission rates, increased levels of vertical transmission always lower the evolutionarily stable (ESS) level of virulence. Contrary to existing theory, however, increases in opportunities for horizontal transmission also lower the ESS level of virulence. We explain these findings in light of earlier work and confirm them in simulations including imperfect vertical transmission. We describe further simulations, in which both vertical and horizontal transmission rates are allowed to evolve. The outcome of these simulations depends on whether high levels of vertical transmission are possible with low virulence. Finally, we argue against the notion of a virulence-avirulence continuum between horizontal and vertical transmission, and discuss our results in relation to empirical studies of transmission and virulence.

NASPGHAN practice guidelines: Diagnosis and management of hepatitis C infection in infants, children, and adolescents

Hepatitis C virus (HCV) is an RNA virus that affects >180 million individuals worldwide with a high propensity for chronic infection. Children with HCV infection differ from adults in several ways including some modes of transmission, rates of clearance, progression of fibrosis, and the duration of potential chronic infection when acquired at birth. Since the discovery of HCV in 1989, there have been significant advances in the understanding of the virology and natural history of chronic HCV infection in children. In addition, there are now several treatment options for children with chronic hepatitis C infection and many new therapies on the horizon. As a consequence, the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition brought together experts in pediatric hepatology to review the available data in children and provide clinicians with approaches to the diagnosis, management, and prevention of HCV infection in children and adolescents. The guideline details the epidemiology and natural history of HCV infection in children, the diagnostic workup, monitoring and treatment of disease, and provides an update on future treatment options and areas of research.

[Hepatitis C and pregnancy: an analysis of factors associated with vertical transmission]

INTRODUCTION

Data concerning hepatitis C virus infection during pregnancy in Brazilian medical services are scarce. This study aimed to verify factors associated with vertical transmission (VT) of HCV in pregnant women.

METHODS

Observational transversal study of pregnant women from Campo Grande, MS, central Brazil, with confirmed reagent serology for HCV infection from 2002 to 2005. Vertical transmission was considered to be positive HCV serology by ELISA, confirmed by PCR, after 18 months of life of the newborn. The factors studied associated with VT were: delivery mode, time of premature rupture of membranes, breastfeeding, blood transfusion history, drug addiction, number of sexual partners and the presence of body tattoos.

RESULTS

Fifty-eight pregnant women with HCV infection were identified, indicating a prevalence rate of 0.2% (58/31,187). Of these 58 pregnant women,23 (39.6%) fulfilled the inclusion criteria. The VT rate was 13% (3/23), and the most frequent HCV viral subtypes were 1a (53%), 1b (30%), 2b (4%) e 3a (13.0%). Two (8.7%) patients were coinfected with HIV. A significant association (p < 0.05) was observed between VT and high maternal serum viremia (> 2.5 x 10(6)) and VT and the use of illicit drugs by the mother.

CONCLUSIONS

The present study demonstrates that high serum maternal viremia for HCV and the use of illicit drugs by the mother are associated with vertical transmission of HCV.

The effectiveness of screening for hepatitis C in pregnancy

OBJECTIVE

to determine the effectiveness of universal versus targeted screening for hepatitis C (HCV) during pregnancy at an urban health care centre.

METHODS

we conducted a cross-sectional study of 653 pregnant women. Patients completed a demographic and standardized questionnaire identifying known risk factors for HCV. Patients then underwent blood testing for HCV antibodies. The effectiveness of screening based on risk factors was determined by comparing the number of women who screened positive for HCV risk factors with those who tested seropositive.

RESULTS

of those who entered the study, 0.5% (3/645) tested positive for HCV. HCV risk factor screening showed that 72% answered "Yes" to one or more risk factors and 28% answered "No" to all risk factors. Answering "Yes" to any risk factor was not associated with testing positive for HCV antibodies (P > 0.05). Screening positive for a high severity risk factor (exposure to intravenous drug use or to the blood of an HCV-positive individual) was associated with testing positive for HCV antibodies (P = 0.002), but screening positive for a moderate or low severity risk factor was not (P > 0.05).

CONCLUSION

during pregnancy, universal testing for HCV and testing based on the presence of any risk factors for HCV is not recommended. HCV testing based on the presence of high severity risk factors, however, may be warranted.

Chronic hepatitis C virus infection in children and adolescents: Epidemiology, natural history, and assessment of the safety and efficacy of combination therapy

Hepatitis C virus (HCV) is the most common cause of chronic liver disease of infectious etiology in children. Most of the children infected with HCV are asymptomatic, and only a few of them develop signs and symptoms of end-stage liver disease early in life. It is not possible to predict either in which patients HCV infection will have a bad outcome or the critical time in early adulthood when disease progression will accelerate. The experiences with therapy in children with chronic hepatitis C are based on earlier and continuing data from adult trials. The currently recommended treatment for chronic HCV infection in adults is the combination of peginterferon-á and ribavirin. The choice of this regimen is based on the results of randomized clinical trials that demonstrated the superiority of this combination treatment over standard interferon-á and ribavirin. Recently, results of pivotal, multicenter, interventional open-label studies on combined treatment with peginterferon-á and ribavirin in children have been published, and the US Food and Drug Administration and the European Medicines Agency have approved the combination therapy in those older than 3 years. The aim of this review is to evaluate critically the available data regarding the safety and efficacy of combination treatment with peginterferon-á and ribavirin in children.

Human immunodeficiency virus-hepatitis C virus co-infection in pregnant women and perinatal transmission to infants in Thailand

OBJECTIVES

The objectives of this study were to assess the prevalence and factors associated with hepatitis C virus (HCV) infection in human immunodeficiency virus (HIV)-infected and -uninfected Thai pregnant women and the rate of HCV transmission to their infants.

PATIENTS AND METHODS

Study subjects included 1435 HIV-infected pregnant women and their infants, enrolled in a perinatal HIV prevention trial, and a control group of 448 HIV-uninfected pregnant women. Women were screened for HCV antibodies with an enzyme immunoassay. Positive results were confirmed by recombinant immunoblot and HCV RNA quantification. Infants were tested for HCV antibodies at 18 months or for HCV RNA at between 6 weeks and 6 months.

RESULTS

Of the HIV-infected women, 2.9% were HCV-infected compared to 0.5% of HIV-uninfected women (p=0.001). Only history of intravenous drug use was associated with HCV infection in HIV-infected women. Ten percent of infants born to co-infected mothers acquired HCV. The risk of transmission was associated with a high maternal HCV RNA (p=0.012), but not with HIV-1 load or CD4 count.

CONCLUSIONS

Acquisition of HCV through intravenous drug use partially explains the higher rate of HCV infection in HIV-infected Thai women than in HIV-uninfected controls. Perinatal transmission occurred in 10% of infants of HIV-HCV-co-infected mothers and was associated with high maternal HCV RNA.

Perinatal transmission of hepatitis C virus infection

In industrialized countries, hepatitis C virus (HCV) is the most common cause of chronic liver disease in children. Perinatal transmission is the leading cause of infection. Perinatal transmission is confined almost always to women with detectable HCV ribonucleic acid (RNA) in the peripheral blood by the polymerase chain reaction but all children born to women with anti-HCV antibodies should be tested for HCV. Some but not all studies found that a high concentration of serum HCV RNA is associated with a higher risk of transmission. Maternal peripheral blood mononuclear cell infection by HCV, membrane rupture of longer than 6 hr before delivery, and procedures exposing the infant to maternal blood infected with HCV during vaginal delivery are associated with an increased risk of transmission. Maternal coinfection with HCV and human immunodeficiency virus, maternal history of intravenous drug use and of HCV infection of the sexual partner of the mother predict the risk of perinatal transmission and are dependent on the peripheral blood mononuclear cell infection by HCV. Delivery by Cesarean section is not recommended in pregnant women infected with HCV. Infected mothers can breast feed safely their infants if the nipples are not damaged. A previous delivery of a child infected perinatally with HCV does not increase the risk of transmission in subsequent pregnancies. Immunogenetic factors and HCV genotypes are not related to HCV perinatal transmission. Despite an increased understanding of the risk factors involved in perinatal transmission of HCV, to date little is known about the transmission mechanisms and timing.

Transmission of hepatitis C virus infection from asymptomatic mother to child in southern India

BACKGROUND

Little information is available on the mother-to-child transmission of hepatitis C virus (HCV) in India, and no interventions to decrease transmission rates have been identified. Hence, we performed a long-term prospective study in infants born to HCV-positive mothers, with the aim of evaluating vertical transmission of HCV and correlated risks factors.

METHODS

Three thousand one hundred and fifteen healthy asymptomatic pregnant women were included in the study. We used third-generation (Murex anti-HCV) ELISA and HCV RNA reverse transcription PCR (RT-PCR) for screening, and the commercial line probe assay (Inno-LiPA) and direct sequencing HCV genotyping assays were performed to confirm the transmitted HCV genotypes.

RESULTS

Of the total 3115 healthy asymptomatic pregnant women, 18 (0.6%) were positive for anti-HCV. Of the 18 anti-HCV-positive women, eight (44.4%) were positive for HCV RNA RT-PCR. HCV transmission was observed in two of the eight babies born to eight HCV RNA-positive mothers who were followed up for 12 months. HCV genotyping of the mother/child pairs revealed the persistent presence of mixed genotypes 1a and 4 throughout the follow-up period. None of the non-viremic (HCV RNA-negative) mothers transmitted HCV infection to their baby. In our study approximately 25% of vertical/perinatal transmission of HCV was observed among HCV RNA-positive antenatal women.

CONCLUSIONS

This study is of importance as it is the first report from India of a successful attempt to analyze the rate of vertical/perinatal transmission of HCV from infected mothers to their children by a prospective longitudinal follow-up study, and to characterize the pattern of genotype(s) of HCV present in the infected mother/baby pairs, so as to confirm the source of HCV acquired by the newborn babies.

The clinical content of preconception care: infectious diseases in preconception care

A number of infectious diseases should be considered for inclusion as part of clinical preconception care. Those infections strongly recommended for health promotion messages and risk assessment or for the initiation of interventions include Chlamydia infection, syphilis, and HIV. For selected populations, the inclusion of interventions for tuberculosis, gonorrheal infection, and herpes simplex virus are recommended. No clear evidence exists for the specific inclusion in preconception care of hepatitis C, toxoplasmosis, cytomegalovirus, listeriosis, malaria, periodontal disease, and bacterial vaginosis (in those with a previous preterm birth). Some infections that have important consequences during pregnancy, such as bacterial vaginosis (in those with no history of preterm birth), asymptomatic bacteriuria, parvovirus, and group B streptococcus infection, most likely would not be improved through intervention in the preconception time frame.

The impact of cesarean delivery on transmission of infectious agents to the neonate

The rate of cesarean deliveries has increased dramatically over the past decade. Studies to date have highlighted a number of factors on the part of the treating physician and the expectant mother contributing to this increase. Maternal infections are not a major cause of this increase. There are a limited number of infections in a pregnant woman that warrant cesarean delivery to prevent perinatal transmission. This article outlines those infections known to be transmitted perinatally through the infected birth canal and details the current recommendations for cesarean delivery. Pregnant women with active genital herpes lesions or with known herpes simplex virus infection and a prodromal illness consistent with recurrence at the time of presentation in labor should undergo cesarean delivery. Pregnant women who are HIV infected and have detectable viremia (>1000 copies/mL) should be counseled regarding the potential benefits of cesarean delivery as an adjunct to antiretroviral therapy. Hepatitis C virus (HCV) can be transmitted intrapartum, but prevention of HCV transmission by cesarean delivery has not been proved effective and is not generally indicated. A limited number of other infectious agents can be transmitted through the birth canal but do not constitute an indication for cesarean delivery.

Hepatitis C and pregnancy

Hepatitis C is the most common chronic bloodborne infection in the United States. The diagnosis of vertical transmission is reliably established by a positive serum hepatitis C virus (HCV) RNA on 2 occasions 3 to 4 months apart after the infant is at least 2 months old and/or by the detection of anti-HCV antibodies after the infant is 18 months old. Vertical transmission in HCV RNA-negative pregnant women is approximately 1% to 3% versus approximately 4% to 6% in HCV RNA-positive women. From the standpoint of vertical transmission, no critical HCV RNA titer has been established. Coinfection with HIV has been shown to increase the risk of vertical transmission of HCV, but highly active antiretroviral therapy may decrease the risk significantly. In HIV-negative women, route of delivery does not influence vertical transmission. In HCV/HIV-coinfected women, decisions regarding mode of delivery should be based on HIV status. There is no association between vertical transmission of HCV and gestational age at delivery or the presence of chorioamnionitis. The use of a scalp electrode has been associated with vertical transmission and this practice is discouraged. Data are conflicting regarding duration of ruptured membranes and the risk of vertical transmission of hepatitis C. When the duration of membrane rupture exceeds 6 hours, the risk may be increased. There is no evidence demonstrating an increased risk of HCV transmission in HIV-negative women who breast feed. In HCV/HIV-coinfected women, breast feeding is discouraged in women who have consistent access to safe infant formula.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall that vertical transmission of hepatitis C (HCV) does occur, state that coinfection with HIV increases the transmission rate, and summarize that there is no association between gestational age or presence of chorioamnionitis and no evidence that a cesarean delivery prevents transmission.

Drug abuse, innate immunity and hepatitis C virus

Since its discovery in 1989, hepatitis C virus (HCV) has become a major public health problem. HCV chronically infects an estimated 170 million people worldwide. The seroprevalence of anti-HCV antibody in the United States has been estimated at 1.8%, which corresponds to approximately 4 million people. HCV is the most common chronic blood borne infection in the United States, and the leading cause of liver transplantation in developed countries. Injection drug use is the dominant mode of HCV transmission and accounts for up to 90% of current infections. Opiates and other drug abuse, such as alcohol, have been implicated as cofactors in the pathogenesis of HCV disease. Injection drug use has been the most common risk factor identified in alcoholics with HCV infection. Both opiates and alcohol contribute significantly to morbidity and mortality from HCV disease. These drugs most likely act synergistically to promote the development and progression of HCV disease. However, there is limited information available concerning the interaction of the drug abuse with the host cell innate immunity against HCV infection, which is a major barrier to fundamental understanding of the immunopathogenesis of HCV disease. Therefore, defining the role of the drug abuse in the development of chronic HCV infection is of crucial importance and should provide practical guidance toward the reduction of risk factors that interfere with therapeutic approaches for HCV infection and disease. This review paper focuses on the interplay between drug abuse (opiates and alcohol), innate immunity and HCV in the context of the development of HCV disease.

Mother-to-infant hepatitis C virus transmission and breastfeeding

Hepatitis C virus (HCV) is a blood-borne virus that is transmitted most efficiently by irect percutaneous exposures to blood. Infants are at risk of HCV infection primarily as a result of transmission from their infected mothers. However, there is no evidence of mother-to-infant transmission from breastfeeding. According to guidelines from the Centers for Disease Control and Prevention and the American Academy of Pediatrics, maternal HCV infection is not a contraindication to breastfeeding. It may be prudent for mothers who are HCV-infected and who choose to breastfeed to consider abstaining from breastfeeding if their nipples are cracked and bleeding.

Breast milk and infection

Three viruses (CMV, HIV, and HTLV-I) frequently cause infection or disease as a result of breast-milk transmission. Reasonable guidelines have been pro-posed for when and how to avoid breast milk in the case of maternal infection. For other viruses, prophylactic immune therapy to protect the infant against all modes of transmission are indicated (VZV, varicella-zoster immunoglobulin, HAV and immunoglobulin, HBV, and HBIg + HBV vaccine). In most maternal viral infections, breast milk is not an important mode of transmission, and continuation of breastfeeding is in the best interest of the infant and mother (see Tables 2 and 3). Maternal bacterial infections rarely are complicated by transmission of infection to their infants through breast milk. In a few situations, temporary cessation of breastfeeding or the avoidance of breast milk is appropriate for a limited time (24 hours for N gonorrheae, H infiuenzae, Group B streptococci, and staphylococci and longer for others including B burgdorferi, T pallidum, and M tuberculosis). In certain situations, prophylactic or empiric therapy may be advised for the infant (eg, T pallidum, M tuberculosis, H influenzae) (see Table 1). Antimicrobial use by the mother should not be a reason not to breastfeed. Alternative regimens that are compatible with breastfeeding can be chosen to treat the mother effectively. In most cases of suspected infection in the breastfeeding mother, the delay in seeking medical care and making the diagnosis means the infant has been ex-posed already. Stopping breastfeeding at this time only deprives the infant of the nutritional and potential immunologic benefits. Breastfeeding or the use of expressed breast milk, even if temporarily suspended, should be encouraged and supported. Decisions about breast milk and infection should balance the potential risk compared with the innumerable benefits of breast milk.

Vertical transmission of hepatitis C virus in a hospital in southern Brazil

BACKGROUND: There still are controversies concerning the vertical transmission of hepatitis C virus. AIM: To evaluate the prevalence of antibodies against hepatitis C virus in pregnant women, as well as the rate of vertical transmission of this virus. PATIENTS AND METHODS: Between August 1998 and November 1999, 1,090 consecutive pregnant women were screened for anti-hepatitis C virus; positive results were confirmed by the polymerase chain reaction assay. Patient's viral load was evaluated by the branched deoxyribonucleic acid assay. Hepatitis C virus genotype was identified by direct sequencing of the polymerase chain reaction amplification products. The same tests were performed in the children born from infected mothers at the 1st and 6th month of life. RESULTS: Of the 1,090 mothers surveyed, 29 were positive for anti-hepatitis C virus (prevalence of 2.66%). Twenty-five patients presented with hepatitis C virus RNA, with a median hepatitis C virus viral load of 3.132 ± 5.891 MEq/mL. Twenty-two patients (six human immunodeficiency virus-coinfected) were followed and gave birth to 23 children; 18 of them had blood samples tested at the 1st month of life, and 22, at the 6th month. Vertical transmission rate was 5.56%; it affected a girl who had hepatitis C virus RNA detectable only in the 1st month sample (41.570 MEq/mL). The mother who transmitted hepatitis C virus was coinfected with human immunodeficiency virus and presented with an hepatitis C virus viral load of 3.765 MEq/mL, with 100% homology with her daughter's hepatitis C virus genotype. CONCLUSION: These results suggest that the prevalence of hepatitis C virus infection in pregnant women should not be neglected, and early diagnosis of vertical transmission and the follow up of infected children should be emphasized.

Risk factors for hepatitis C infection among sexually transmitted disease-infected, inner city obstetric patients

Objective: To test the hypothesis that our inner city obstetric patients who have been infected with sexually transmitted diseases (STDs) will have a higher prevalence of hepatitis C virus infection than the general population and to identify specific risk factors and high-risk groups.

Methods: All patients in our prenatal clinic (July 1997–April 1999) who tested positive for one or more STDs were asked to return for hepatitis C antibody testing. Medical charts of all patients who returned for hepatitis C testing were reviewed.

Results: A total of 106 patients with STDs were tested for hepatitis C. Positive screening tests for anti-hepatitis C antibody were found in 6.6% (7/106) of the patients (95% CI = 2.7–13.1%). This frequency is significantly higher than the hepatitis C prevalence (1.8%) in the general United States population (p = 0.006). Multiple logistic regression analysis confirmed only older age (p = 0.016) and positive HIV status (p = 0.023) to be significant predictors of hepatitis C infection.

Conclusions: Inner city STD-infected obstetric patients are at high risk for hepatitis C infection compared with the general population. Increasing age and HIV-positive status are risk factors which are significantly associated with hepatitis C infection.

Maternal-infant transmission of hepatitis C virus infection

Mother-to-infant transmission of hepatitis C virus (HCV) is comparatively uncommon. The prevalence of antibody to HCV (anti-HCV) in pregnant women is 0.1% to 2.4%, although in some endemic areas it is much higher. The proportion of women with anti-HCV who have active infection with viremia is 60% to 70%. Transmission of HCV occurs only when serum HCV RNA is detectable and may be related to higher levels (above 10(6) copies per mL). The rate of mother-to-infant transmission is 4% to 7% per pregnancy in women with HCV viremia. Co-infection with human immunodeficiency virus (HIV) increases the rate of transmission 4 to 5 fold. The actual time and mode of transmission are not known. Elective Cesarean section is not recommended for women with chronic HCV infection alone. The role of treatment to prevent transmission is limited by the fetal toxicity of currently available medications for hepatitis C. Breast feeding poses no important risk of HCV transmission if nipples are not traumatized and maternal hepatitis C is quiescent. Pregnant women at high risk for HCV infection should be screened for anti-HCV, and HCV RNA testing should be performed if anti-HCV is positive. Infants of women with hepatitis C should be tested for HCV RNA on two occasions, between the ages of 2 and 6 months and again at 18 to 24 months, along with serum anti-HCV. The natural history of mother-to-infant hepatitis C remains uncertain, especially the course in the first year of life when some infants appear to have spontaneous resolution.

Maternal-infant transmission of hepatitis C virus infection

Mother-to-infant transmission of hepatitis C virus (HCV) is comparatively uncommon. The prevalence of antibody to HCV (anti-HCV) in pregnant women is 0.1% to 2.4%, although in some endemic areas it is much higher. The proportion of women with anti-HCV who have active infection with viremia is 60% to 70%. Transmission of HCV occurs only when serum HCV RNA is detectable and may be related to higher levels (above 10(6) copies per mL). The rate of mother-to-infant transmission is 4% to 7% per pregnancy in women with HCV viremia. Co-infection with human immunodeficiency virus (HIV) increases the rate of transmission 4 to 5 fold. The actual time and mode of transmission are not known. Elective Cesarean section is not recommended for women with chronic HCV infection alone. The role of treatment to prevent transmission is limited by the fetal toxicity of currently available medications for hepatitis C. Breast feeding poses no important risk of HCV transmission if nipples are not traumatized and maternal hepatitis C is quiescent. Pregnant women at high risk for HCV infection should be screened for anti-HCV, and HCV RNA testing should be performed if anti-HCV is positive. Infants of women with hepatitis C should be tested for HCV RNA on two occasions, between the ages of 2 and 6 months and again at 18 to 24 months, along with serum anti-HCV. The natural history of mother-to-infant hepatitis C remains uncertain, especially the course in the first year of life when some infants appear to have spontaneous resolution.

Mother-to-infant transmission of hepatitis C virus: rate of infection and assessment of viral load and IgM anti-HCV as risk factors

One hundred twenty-six mother-infant couples were studied and 105 exposed babies were monitored for at least 12 months to define the risk of mother-to-infant HCV transmission. Infection occurred in 5 out of 76 infants (6.6%) born to 69 viraemic mothers and in none of 29 born to 26 non-viraemic mothers. Only one child was HCV RNA positive one month after birth, while the remaining children became positive at the 3rd to 4th month. HCV genotypes of the babies matched those of their mothers. No difference was found between women who transmitted the virus and those who did not with regard to age, history of drug abuse, HIV infection, ALT abnormal values, HCV genotype, type of delivery, and breast-feeding. Four out of 5 infected infants were born to mothers with IgM anti-HCV (P = 0.04). The mean viral titre in transmitting women (10(7.2)) was higher than in non-transmitting (10(6.5)), and the proportion of mothers with viral load > or = 10(7) was statistically higher in transmitting than non-transmitting women (P = 0.03). These data show that HCV perinatal infection is a rare event and suggest that IgM positivity and high viral load (> or = 10(7)) in the mother are independent variables correlated with HCV transmission (O.R. = 14.5; 95% CI: 1.3-160.7 and O.R. = 16.3; 95% CI: 1.5-179.9, respectively).

[Hepatitis C and pregnancy]

PURPOSE

Today, the natural course of hepatitis C virus (HCV) infection during pregnancy and the prevalence of mother-to-child transmission are better known.

CURRENT KNOWLEDGE AND KEY POINTS

Antenatal screening for HCV infection needs to be proposed to women with risk factors. Viral replication needs to be confirmed by PCR in pregnant women with antibodies against HCV. To date, the clinical course of pregnancy and the mode of delivery have not been changed by HCV infection. Rates of vertical transmission of HCV are about 6% in women with HCV alone and 15% in women co-infected with HIV. A screening for HCV markers is required 18 months after delivery for infants born to HCV mothers. Because of the relatively low rate of HCV vertical transmission, pregnancy can be allowed in infected women. However, taking into account the efficacy of new antiviral strategies, treatment of HCV infection could be proposed before pregnancy.

FUTURE PROSPECTS AND PROJECTS

In case of HCV infection, a careful follow-up of both mother and newborns is required. Long-term follow-up of infected infants is needed to assess the consequences of perinatal HCV infection.

Clinical course of pregnant women with chronic hepatitis C virus infection and risk of mother-to-child hepatitis C virus transmission

As far as concerns chronic hepatitis C virus infection in pregnant women, different points remain to be elucidated, such as the clinical course, the rate of mother-to-child hepatitis C virus transmission and, in particular, its route and the possible risk factors. This review aimed to analyse current data on the prevalence of chronic hepatitis C virus infection in pregnant women and its relationship with risk factors, the rate of mother-to-child hepatitis C virus transmission and the factors possibly involved, particularly the maternal hepatitis C virus viral load and the human immunodeficiency virus coinfection, and the type of delivery and feeding. Finally, the appropriate timing for HCV-RNA testing in newborns has been reviewed.

Given the benefits of breastfeeding, what contraindications exist?

Breastfeeding is not contraindicated in association with environmental hazards in the United States under ordinary circumstances. Unusual massive exposure should be assessed on an individual basis. In the face of any possible contraindication to breastfeeding, the tremendous benefits of being breastfed should be compared with the theoretic risk for the hazard involved and a decision made on an individual basis.

[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.

Evolution in the hypervariable region of hepatitis C virus in infants after vertical transmission

To elucidate the clonal evolution of hepatitis C virus (HCV) during mother-to-infant transmission, we prospectively analyzed HCV clones of the hypervariable region in four HCV RNA-positive infants and compared them with those of the mother. Cord blood samples from three of the four infants were positive for the HCV RNA (< or =10(3) copies/mL), and all of the four infants had the HCV RNA titer of >10(6) copies/mL within 2 mo after birth. The hypervariable region clones detected in the infants were closely related to those in the respective mothers. The results suggest the perinatal transmission of HCV. The hypervariable region clones transmitted to infants were not a single selected clone or minor clones in the mother. None of the clones specific to the low-density fraction in the mother was transmitted to the infants. Moreover, the proportion of HCV in the low-density fraction was minimal in the first few months of life, but increased several months after birth in association with the elevation of alanine aminotransferase. These results suggest that the increase of HCV in the low-density fraction reflect the evolution of immune response in infants. We also demonstrated that the emergence of quasispecies in infants precedes the infantile antibody response.

Prevalence of anti-hepatitis C virus antibody and chronic liver disease among atomic bomb survivors

To investigate whether exposure to atomic bomb radiation altered the prevalence of hepatitis C virus (HCV) infection or accelerated the progress toward chronic hepatitis after HCV infection, the seropositivity of antibody to hepatitis C virus (anti-HCV) was determined for 6,121 participants in the Adult Health Study of atomic bomb survivors in Hiroshima and Nagasaki. The seropositivity of anti-HCV antibody was 2.5 times higher among those with a history of blood transfusion and 1.2 times higher among those with a family history of liver disease, whereas acupuncture showed no association with anti-HCV. Although the prevalence of anti-HCV was lower for survivors with positive dose estimates than for those with 0 dose (relative prevalence 0.84, P = 0.022), there was no evidence of a smooth dose-response relationship. However, these data suggested that the radiation dose response for chronic liver disease among HCV antibody-positive survivors may be greater than that among HCV antibody-negative survivors (slope ratio 20). In conclusion, no dose-response relationship was found between anti-HCV positivity and radiation dose; a possible increase in the radiation dose response of chronic liver disease among anti-HCV-positive individuals was found. Thus radiation exposure may accelerate the progress of chronic liver disease associated with hepatitis C virus infection.

Follow-up of transmission of hepatitis C to babies of human immunodeficiency virus-negative women: the role of breast-feeding in transmission

BACKGROUND

The studies on hepatitis C virus (HCV) vertical transmission, the effect of potential risk factors and the role of breast-feeding have reported conflicting results.

PATIENTS AND METHODS

Seventy-three infants of 63 anti-HCV-positive and anti-HIV-negative mothers were studied from 1993 to 1999 in the south of Spain. The mean period of follow-up in children was 29.2 +/- 19 months (range, 8 to 76 months); 6 (8%) children were lost to follow-up. Breast milk was studied for HCV-RNA in 68 samples of 35 mothers.

RESULTS

Alanine aminotransferase was high in 19 (26%) and HCV-RNA was positive in 46 (63%) pregnant woman. Breast milk HCV-RNA was negative in nonviremic mothers and positive in 20% of the viremic mothers. The overall rate of vertical HCV transmission was 11.9% (n = 8) (95% confidence interval, 6 to 23%) if HCV-RNA was positive one or more times, but only 1.5% (n = 1) (95% confidence interval, 0.1 to 9%) if HCV-RNA was permanently positive. Seven HCV-infected children did not develop antibodies to HCV, and they had a spontaneous clearance of the virus. A 10-month-old baby was HCV-RNA-positive from birth to the end of the follow-up. The genotype in each of the infants was consistent with that of their mother. The rate of HCV transmission was higher for infants of mothers with higher HCV viremia (P < 0.01) and also for infants whose mothers were HCV-RNA-positive in breast milk (P < 0.05). There were no statistically significant differences between other risk factors.

CONCLUSION

The presence of transitory viremia without seroconversion indicates that the vertical transmission of HCV is not important. This could be related to the viral charge and ingestion of milk of HCV-RNA-positive mothers. However, to advise avoidance of maternal breast feeding, it would be necessary to conduct larger studies.

HCV: epidemiology, modes of transmission and prevention of spread

Approximately 3% of the world's population has been infected with the hepatitis C virus (HCV), which represents about 170 million chronic carriers at risk of developing serious complications. Following the introduction of screening of blood donors for infection the risk of transmitting HCV by blood products is presently at 1/200,000 units distributed. Intravenous (i.v.) drug users are currently the main risk group with a prevalence rate of about 80% and a yearly incidence varying between 4 and 6%. Vertical and sexual transmissions have also been implicated but data are limited and sometimes controversial. The source of infection for the 30% of cases without an identifiable risk factor remains to be clarified. Prevention of spread includes detailed information of persons at risk of being infected, screening of high-risk populations, strengthening of syringe exchanges among i.v. drug users and strict application of disinfection procedures for all invasive medical equipment.

Hepatitis C epidemiology

Hepatitis C virus infection occurs in all parts of the world. Infection is generally due to percutaneous exposures, though sexual and perinatal transmission may occur. While further study is needed to elucidate the biology of HCV transmission and develop vaccines for prevention, new HCV infections can be reduced by economic development and education regarding blood-borne infections.

Shift in the buoyant density of hepatitis C virus particles in infants infected by mother-to-infant transmission

BACKGROUND

Hepatitis C virus (HCV) particles in sera can be divided into two classes: low-density free particles and high-density immune complex particles. Previous studies have revealed that the clinical progression of HCV infection is closely associated with the occurrence of the former class, rather than the latter, in an experimental chimpanzee model and in HCV-infected adult cases.

METHODS

To verify this concept in infantile cases, we prospectively analysed HCV particle populations, fractionated according to buoyant density, in serum samples from five infants infected by mother-to-infant transmission.

RESULTS

In all five cases, HCV particles were predominantly high density at the age of one month. In four of five cases, low-density HCV particles became predominant in association with a decrease in maternally transmitted antibody levels. In one case, in which high serum levels of alanine aminotransferase persisted, low-density particles were predominant between the ages of 3 and 9 months, in three consecutive samples. In other cases, in which infants were asymptomatic or had transient hepatitis, low-density HCV particles were predominant at only one sampling point or not at all throughout the follow-up period.

CONCLUSIONS

Maternal antibody transmitted via the placenta reacts with the HCV particles in infants infected through vertical transmission. A decrease in maternal antibody levels results in an increase in low-density free virions. It is suggested that low-density particles play an important role in liver inflammation.

Seroprevalence and mother-to-infant transmission of hepatitis C in asymptomatic Egyptian women

OBJECTIVES

In this study, we sought to determine (1) the prevalence of hepatitis C virus (HCV) RNA, or its antibodies, in a healthy parturient Egyptian population and (2) the risk of mother-to-infant transmission in this population.

METHOD

The serum of 499 pregnant Egyptian women was tested for anti-HCV with ELISA-3 and for HCV RNA by polymerase chain reaction (PCR). Neonatal cord blood and infant blood were similarly tested for anti-HCV and HCV RNA.

RESULTS

Recombinant immunoblot assay (RIBA) detected anti-HCV in 65/499 (13%) women; of these, 20/65 (31%) were PCR-positive. The total number of babies born was 499. Of the original group, 97 mothers and infants (HCV-negative) were lost to follow up and were excluded. Sixty-five anti-HCV-positive infants were born vaginally to the 65 anti-HCV-positive mothers, of which twenty (31%) corresponding mothers and babies were also positive for HCV RNA. Of these twenty babies, three died of hepatocellular disease by six months of age; sixteen developed chronic liver disease; the remaining nine remained asymptomatic but were serologically and PCR-positive. The mother-to-infant transmission rate was significantly increased (5%; P < 0.0001). Of the seropositive children, 45/65 (69%; P < 0.0001) seroreverted by eighteen months of age.

CONCLUSION

There is a high prevalence of anti-HCV in healthy pregnant Egyptian women and vertical transmission is a major risk for chronic HCV carriers.

Hepatitis C virus infection in pediatric patients

In contrast to our understanding of hepatitis C virus infection in adults, relatively little is known about the evolution and treatment of HCV infection in pediatric patients. Children at risk for HCV infection include recipients of multiple blood-product transfusions, organ transplantation and infants born to HCV-infected mothers. A proportion of HCV-infected pediatric patients do not have an identifiable risk factor. HCV infection is commonly detected in children previously presumed to have non-A, non-B hepatitis and cryptogenic liver disease. HCV infection usually leads to mild chronic liver disease in children but is also associated with chronic active hepatitis and cirrhosis. Interferon therapy is effective in a proportion of patients with chronic hepatitis C.

Second generation hepatitis C virus antibody-positive rate in children: investigation of the route of hepatitis C virus infection in children with no history of transfusion

Hepatitis C virus (HCV) antibody and HCV-RNA screening was undertaken in 1864 children, aged from 0 to 15 years who did not have a history of transfusion. Anti-HCV was tested by the second generation enzyme-linked immunosorbent assay (ELISA). HCV RNA was examined by reverse transcriptase-nested polymerase chain reaction (PCR). Two of the 1864 children were positive for serum HCV RNA. They had no history of transfusion, no episodes of horizontal transmission, but the mother in each case was positive for serum HCV RNA, implying mother-to-infant infection. Eleven children who were positive for HCV antibody with low values and negative for serum HCV RNA were classified as belonging to the high bovine milk (composed primarily of casein)-specific IgG4 value group. This suggested that many of the children who were falsely positive for HCV antibody using ELISA had antibodies to casein.

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.

Loss of circulating hepatitis C virus in children who developed a persistent carrier state after mother-to-baby transmission

Of the 15 babies born to mothers infected with hepatitis C virus (HCV) and followed since birth, three developed HCV RNA in their serum. HCV RNA disappeared in two infants within 2 mo, but it persisted in the remaining infant. Mother-to-baby transmission was diagnosed retrospectively in an additional eight children aged 0.8-13.6 y. The eight children were followed for 1.4-5.0 y (mean +/- SD: 3.2 +/- 1.3 y) until they were 3.3-16.7 y old (8.5 +/- 4.3 y). Serum HCV RNA disappeared and antibodies to HCV decreased in the titer in two of the children when they were 3 y old. The spontaneous loss of serum HCV RNA was not observed in any of the other 14 children with posttransfusion infection who were followed for 2.6-6.1 y (4.0 +/- 1.1 y), until 3-22 y from the time they received transfusions and when they were 8.4-22.8 y old (15.4 +/- 4.1 y). These results indicate that the vertical transmission of HCV is rare, and some children can resolve the infection after a few years, whereas the infection persists in children who are infected by transfusion.

The prevalence of HCV infection in a cohort of pregnant women, the related risk factors and the possibility of vertical transmission

The prevalence of antibodies for one or more HCV antigens was 2.3% of 1,347 mothers at childbirth. Compared with the principal factors studied, the presence of antibodies was more frequent in women who were carriers of HIV infection (3/3), in those who had suffered liver diseases (5/37) or who had had transfusion (3/25). This was as opposed to women who did not have any risk factor (p < 0.001). The prevalence of HCV-RNA was 1.3%; in relation to the antibody state, such a condition was more frequent in subjects with antibodies for 3 or 4 antigens (about 80%) compared with those who were positive for 1 or 2 antigens. HCV-RNA of the same genotype as the mother (type 1; 1a) was also found in the funicular blood of 2 of the 18 babies born to mothers who were positive for HCV-RNA. In the course of the follow-up (from the 3rd to the 18th month) the viral RNA was not found in any of the babies, nor was it found in the 2 who were positive at birth. Even the antibodies gradually disappeared, although slowly. At the 10th month, 91% of the babies resulted as having no antibodies and at the 18th month none of the babies resulted as having antibodies. Breast-feeding also appeared to have no influence on the transmission of the infection; out of 18 viremic mothers indeed 12 (67%) breast-fed their babies.

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.

Hepatitis C virus infection in pregnancy and the risk of mother-to-child transmission

The risk of vertical transmission of the hepatitis C virus (HCV) from infected mothers to their children during pregnancy and delivery was determined in 120 children born to HCV-positive mothers. Methods included enzyme immunoassay and immunoblot for detection of HCV antibodies and reverse transcription polymerase chain reaction (RT-PCR) for detection of viral RNA. Six (5%) children were perinatally infected with HCV as shown by RT-PCR. None of the infected children had clinical signs of hepatitis. None of the pregnancies was complicated by abortion, stillbirth, premature birth, or malformation of the child. Special concern was given to the possibility of HCV transmission via breast milk. In no breast milk sample obtained from 34 HCV-infected mothers was HCV RNA detected. These observations indicate that HCV infection is not necessarily a contraindication for breast-feeding.

Vertical transmission of hepatitis C virus: an epidemiological study on 2,980 pregnant women in Italy

The risk of mother-to-infant transmission of hepatitis C virus (HCV) varies according to the population studied and the tests used. Aim of the current study was to investigate HCV vertical transmission rate in children born to 30 HCV positive/HIV negative pregnant women in Italy. We investigated the potential vertical transmission of HCV by identifying HCV antibody seropositive pregnant women, by analyzing HCV-RNA in the peripheral blood using PCR and by prospectively following their offspring until 24 months of age. During the third trimester, 2,980 consecutive pregnant women were examined for anti-HCV antibodies by a second generation Enzyme-Linked Immunosorbent Assay (EIA2) and re-assayed by a second generation Recombinant Immunoblot Assay (RIBA2). A total of 32 mothers (1.07%) were positive for EIA2 test; 30 out of 32 had a reactive confirmatory RIBA2 test for HCV. All anti-HCV positive mothers were negative for HIV. These 30 mothers and their 30 babies formed the study cohort. Of the 30 anti-HCV positive mothers, 10 were also positive for serum HCV-RNA by PCR. All the babies born to the 30 anti-HCV positive mothers were initially negative for HCV-RNA (cord blood specimens), but three babies became positive at three months of age and remained positive thereafter. These babies had been born to 3 of the 10 mothers with viremia during the third trimester of pregnancy. These results suggest that HCV vertical transmission is possible in 10% of anti-HCV positives and in about 33% of the HCV-RNA seropositive mothers.