Transmission of hepatitis C virus: rates, routes, and cofactors.

Abstract

The existence of a viral cause of hepatitis other than hepatitis A and hepatitis B was first recognized in the early 1970s following the development of diagnostic blood tests for hepatitis A and hepatitis B. Early studies showed that appreciable proportions of people presenting with acute hepatitis following blood transfusion or community-acquired hepatitis did not have any serologic evidence of hepatitis A or hepatitis B (1-3). While some epidemiologic aspects of a putative etiologic agent, including transmissibility by blood contact, could be inferred from early studies of nonA, nonB hepatitis, it was not until tests for hepatitis C virus (HCV) antibody became available in 1989 that it was recognized that nonA, nonB hepatitis was predominantly caused by HCV in developed countries (4-6), and the development of HCV epidemiology began in earnest. Significant advances have been made over the past 5 years in our understanding of the epidemiologic patterns of HCV transmission, prevalence, and natural history, but much remains to be learned in all these areas. Transmission of HCV is recognized as being primarily through blood contact, but this route does not fully explain HCV transmission. There has been less certainty about the role of other routes of transmission and factors which modify the efficiency of transmission. In this presentation, we review the current state of knowledge regarding the transmission of HCV and address the major methodological problems and requirements for future research.