Summerová M., Köning J., Turek P.: Screening and Confirma-tion of Blood Donors at the Czech Republic

Overview

Screening of blood donors for the presence of markers of infection with hepatitis B and C viruses isone of the main provisions to prevent the spread of these serious human pathogens. The incidence ofacute hepatitis B declined significantly during the last 15 years and was 6.2 cases per 100 000 populationin 1999. The age structure of acute viral hepatitis B is also changing. The prevalence of carriers ofHBsAg in the general population declined also and in 1996 it was 0.66%. The incidence of acute hepatitisC is rising and was 3.2 cases per 100 000 population in 1999. The prevalence of anti-HCV in thepopulation of the Czech Republic is not known. From 1993 data are available on the number of donorsand primary donors eliminated on account of HBV and HCV markers. The annual relative numbers ofprimary donors eliminated on account of HBV are most frequently within the interval of 0.2 - 0.3%, onaccount of HCV 0.6 - 0.8 % with a more marked decline in 1999. Reactive findings of HBsAg withanti-HCV during screening of blood donors are confirmed according to the mentioned procedures inthe National reference laboratory for viral hepatitis. From the analyzed group of 722 samples sent forconfirmation of anti-HCV only in 55.1% of samples values of the reactivity during the initial screeningin laboratories of the transfusion service were given. The results of the initial screening of these sampleswere in 77.4% reactive, in 13.6% in the „gray zone“ (S/CO 0.8-1.0) and in 9% of the samples negative (withS/CO values of 0.7-0.8 in the majority). The results of the confirming examination of 722 specimens werein 13.6% positive, in 57.5% negative and in 28.9% not unequivocal. In the confirming exa minations theauthors included also assessment of HBV DNA and HCV RNA as supplementary examinations. Compre-hensive confirming examinations using several methods lead to a more reliable, more standardized andmore effective confirmation of the specificity of screening examinations of HBsAg and anti-HCV.

Key words:
hepatitis B, hepatitis C, blood donors, confirmation, prevalence