Hepatitis viruses: Hepatitis C

Abstract

Hepatitis C virus (HCV), a member of the Flaviviridae family, is a bloodborne pathogen infecting approximately 170 million persons representing around 3 % of the population worldwide, with substantial variability in prevalence in different geographic regions. It is a leading cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma, as well as the most common indication for liver transplantation in many countries. It is a major public health problem and a leading cause of morbidity and mortality. The major route of transmission is via exposure to infected blood, so that infections are commonly seen resulting from transfusions where the blood supply is not screened or the sharing of works by injection drug users. Sexual, perinatal, and occupational injury transmission also occur. Although limited in scope, health-care-related outbreaks have been seen due to poor infection control. While the incidence of HCV infection has decreased during the last several decades, because of the prolonged duration between infection and the development of the major liver-related complications resulting from infection, the prevalence of those complications continues to rise. A minority of persons infected with HCV clears the virus spontaneously; most develop chronic infection. In the USA, it is estimated that three-quarters of infected persons are unaware of their HCV infection. Because HCV infection is most often asymptomatic until the late complications of advanced liver disease, diagnosis of chronic HCV infection usually depends on asymptomatic screening of at-risk individuals or those with elevations of serum transaminases. Among persons with chronic HCV infection, factors associated with more rapid liver fibrosis include older age at time of infection, male gender, obesity, hepatic steatosis, insulin resistance, hepatic iron overload, and coinfection with hepatitis B virus or human immunodeficiency virus. However, not all persons with chronic HCV infection progress to cirrhosis or end-stage liver disease. More than one-third of persons with chronic HCV infection have one or more symptomatic extrahepatic manifestations. Because HCV infection is preventable, it should be a key focus of clinical and public health interventions. Unless a vaccine becomes available, prevention of HCV acquisition depends on minimizing exposure by eliminating transfusion of infected blood products, reducing high-risk behaviors, and optimizing infection control practices. HCV is also treatable, and when successful, infection can be eradicated with elimination of transmission risk for the treated individual. While treatments options are increasing with the recent and ongoing development of oral therapies, optimizing reduction of transmission depends on identifying and treating asymptomatic infected persons as well as those who are ill. It is important to note that cure does not prevent reinfection, since there is no long-term natural immunity to HCV reinfection.