[Transmission of hepatitis C viruses: certainties and hypotheses]

Since the identification of the hepatitis C virus in 1989, much progress has been made in understanding viral transmission. It is now known that the major route of contamination occurs via parenteral transmission (blood transfusion, injections, intravenous drug abuse, haemodialysis...). We are however less certain about sexual, mother-child, and person to person transmission. Several cofactors have been suggested as influencing transmission including the stage of the disease, coinfection with the human immunodeficiency virus, level of the viral load, and type of virus. There are also still some questions as to the level of the residual post transfusion HCV infection risk since the implementation of HCV screening of blood donors. Based on scientific data currently available, parenteral transmission can be prevented, but it is still difficult to elaborate clearcut recommendations to reduce non-parenteral transmission, especially in couples with an infected partner. Emphasis must be placed on reducing the transmission of hepatitis C virus (and the human immunodeficiency virus) in drug abusers and on controlling nosocomial transmission through the strict implementation of universal precautions.