Hepatitis C virus infection in children.

The prevalence of hepatitis C virus (HCV) infection is relatively low in childhood, with anti-HCV prevalence rates of 0.1-0.4% in the Western world. To date, blood transfusion has been the principal route of acquisition of HCV in children, but there is evidence that vertical transmission is overtaking it. The overall risk of vertical perinatal transmission of HCV is about 5%, although it increases with HIV co-infection and higher maternal viraemia. The mode of delivery and breastfeeding do not seem to affect the vertical transmission of HCV. Diagnosis of perinatal transmission relies on determination of ALT levels and the presence of HCV after the second month, while maternal anti-HCV antibodies may persist until 18 months of life. After infancy, a variable percentage of perinatally infected children are anti-HCV negative; thus, detection of HCV-RNA is necessary for accurate diagnosis. The natural history of HCV in childhood is not well understood and the outcome depends on host and viral factors. The rate of progression to chronicity is about 60-80% in both post-transfusion and vertically acquired HCV infection. Compared with adult patients, chronic hepatitis C in children is characterized by both low ALT levels and low viral load, as well as by the mildest histological and immunohistochemical forms of chronic hepatitis. The prognosis is usually worse in multitransfused, thalassaemic children and those who have had cancer. Experience of treatment of chronic hepatitis C in children is limited, with about 40% having a sustained response to the interferon therapy. It is necessary to perform long-term follow-up and multicentre treatment studies to improve knowledge of the natural history of HCV in children, as well as that of the efficacy of anti-viral therapy in childhood.