[The diagnostic tools of hepatitis C virus infections].

SERIOLOGICAL TESTS IN FIRST INTENTION: Aimed at revealing antibodies demonstrating the contact of the patient with the hepatitis C virus. There are two types of serological tests: ELISA for the global screening of various antibodies and immunoblot for the isolation of the various antibodies. QUALITATIVE RNA OF HCV: The positive qualitative detection of RNA of the hepatitis C virus in a patient exhibiting anti-HCV antibodies confirms an active infection. In the case of negative qualitative detection in a patient exhibiting anti-HCV antibodies, viral eradication is probable and should be controlled later on. MEASURING THE VIRAL LOAD: Two types of measuring techniques are used to quantify the circulating viral RNA: gene amplification and amplification of the signal. The extent of the viral load will help to guide the selection and duration of the anti-HCV dual therapy, associating pegylated interferon and ribavirin. The kinetics of the decrease in viral load are part of the therapeutic follow-up. HCV typing Many viral strains have been isolated, demonstrating its genetic variability and have led to the development of genotyping. The latter is useful in selecting the right therapy and duration of treatment, because the response depends on the genotype (better response rate for the genotypes 2 and 3).