Most children with hepatitis C contract the virus through transmission from their chronically infected mothers, either in the womb or at birth, particularly when an expectant mother also is HIV-positive.
The primary way most children with hepatitis C contract the virus is through transmission from their chronically infected mothers either in the womb or at birth, particularly when an expectant mother also is HIV-positive, according to a quantitative statistical analysis summarized in Clinical Infectious Diseases.
The meta-analysis, which drew from updated data from various sources, found that more than one in 20 infants born to women who are chronically infected with hepatitis C are also infected with the virus. Mother-to-child vertical transmission of the disease is likely the primary way the virus spreads to children, lead author Lenka Benova stated in an advanced access version of the journal article published June 13 in Clinical Infectious Diseases.
The risk of vertical hepatitis C virus (HCV) infection to children of HCV-antibody positive and RNA-positive mothers appears to depend in part on whether the mother was also coinfected with HIV. The risk ranged from 5.8% (95% confidence interval [CI]: 4.2-7.8) for children of HIV-negative (no detection in the blood) mothers and nearly doubled to 10.8% (95%CI: 7.6-15.2) for children of HIV-positive mothers, the article states.
“Maternal HIV co-infection was the most important determinant of vertical transmission risk,” the authors conclude.
Hepatitis C is a bloodborne virus that attacks the liver. About one-third of people infected clear the virus spontaneously with the help of their own immune system, while the remaining newly infected develop chronic infection. Over time if not treated, HCV can lead to cirrhosis, liver cancer, and the need for a liver transplant.
Some 25 years after HCV was discovered, there is no vaccine to prevent it. However, advancements in drug development in recent years have led to effective but often costly treatments that can clear the virus from the blood stream. Doctors consider a patient cured when a sustained virologic response is achieved, meaning that hepatitis C viral load is undetectable in lab tests typically six months after treatment of the chronic condition.
To collect the information for the meta-analysis, researchers conducted a literature search using PubMed and Embase and ultimately included 109 articles in their review to approximate the global magnitude of mother-to-child HCV transmission. They pooled estimates of vertical transmission risk (separately by maternal HIV-coinfection, and for children born to viremic women who were HCV-antibody positive) and they referenced only studies using 2nd or later generation tests for determining HCV antibody presence.
The authors noted that the average age for children with transient RNA positivity to clear the virus is 15 months old and that 95% of them who are diagnosed as uninfected will lose maternal antibodies by the time they are a year old.
“In addition to circulating HCV viremia, the presence of HCV antibodies at or beyond 18 months of age has been used as a surrogate measure of infection,” the authors stated. “Therefore, only datapoints which assessed HCV vertical transmission risk in samples of children followed to age 18 months or older were included.”
How and when transmission of the virus from mother to child occurs is not fully understood and effective prevention methods have not been established. The authors noted some evidence suggests that prolonged rupture of membranes may cause an increased risk of vertical transmission, but addedthat caesarean-section is not currently recommended as a risk-reducing intervention.
The analysis employed a framework that captured 25 different types of vertical transmission risk estimates based on presence of maternal HCV antibody and viremia (circulating virus particles in the blood) during pregnancy or at delivery. The systematic review included more than a decade of new evidence, with 17 of the 25 datapoints taken from studies published since 2001, when the last review was conducted.
“This study highlighted the importance of using a standard definition of HCV infection in vertically exposed children,” the authors wrote. “Additional risk factors warrant further examination in primary research, namely maternal HIV treatment and HCV genotype.”