Epidemiology of the hepatitis C virus.

According to WHO estimations, about 3% of the world population may be infected with the hepatitis C virus. The relative prevalences of subtypes of this virus vary in different geographic areas. The main known routes of transmission are parenteral; intravenous drug abuse, contaminated injection devices and receipt of unscreened blood. Sexual, vertical, household and nosocomial transmissions may occur, but seem to be rare. The risk of screened blood or blood products is now almost eliminated, but unscreened blood is a considerable risk in areas where screening is economically not possible. The future impact of this virus is greatly dependent on the trends in intravenous drug use as well as the possible emergence of increased late morbidity among present asymptomatic carriers during the next decades.