Hepatitis C virus seroconversion rate in established blood donors

Abstract

The results of hepatitis C virus (HCV) antibody test of 237,813 blood donations collected from 143,815 donors by the West Midlands Blood Transfusion Centre in 1993 were analyzed retrospectively in order to determine the seroconversion rate among established previously anti-HCV negative donors. Three hundred sixteen (0.22%; 1 in 455) donors were positive by the enzyme linked immunosorbent assay (ELISA) screening test and 34 (0.024%; 1 in 4,230) donors were positive by ELISA and the Recombinant Immuno Blot Assay (RIBA). Three donors previously negative for HCV antibody reacted positively by both tests. The annual seroconversion rate was calculated as one in 35,937 donors. This figure argues against limitation of HCV antibody screening to new blood donors. A further 45 donors negative on previous screening reacted positively by ELISA and were indeterminate by RIBA. Unexpectedly, lapsed blood donors first tested for HCV antibody in 1993 had high positive reaction rates by ELISA and RIBA, which was significantly (P < 0.001) higher than those of new donors. RIBA-positive reaction rate among ELISA-positive donors was significantly higher amongst males than females (P < 0.001).

Incidence of seroconversion to positivity for hepatitis C antibody in repeat blood donors in England, 1993-5

“…The blood centre obtained denominators of previously negative donors tested for hepatitis C antibody during 1993 and estimated the seroconversion rate during 1993 to be 2.78 per 100 000 (1 in 35 937) previously negative, repeat donors3: more than 10 times the estimate from our national study. However, the case definition used by this centre may have been flawed 7 8; only one of the cases described satisfied the case definition that we used.…”

“…One blood centre has published reports about three cases diagnosed during 19933 and a further four cases diagnosed during 1994 and 19956 in which seroconversion was thought to have occurred. The blood centre obtained denominators of previously negative donors tested for hepatitis C antibody during 1993 and estimated the seroconversion rate during 1993 to be 2.78 per 100 000 (1 in 35 937) previously negative, repeat donors3: more than 10 times the estimate from our national study.…”

Hepatitis C : A Brief Clinical Overview

“…A negative HCV RNA by PCR or b-DNA assay usually excludes the diagnosis of HCV except on rare occasions, such as in low-risk (normal alanine transaminase), anti-HCV, positive patient blood donors. Under these circumstances, a recombinant immunoblot assay (RIBA 1 ) is needed to determine whether the positive anti-HCV test represents a true positive (Atrah et al 1995). The appearance of bands of different densities from at least two of the four viral proteins on the immunoblot is considered a positive RIB A test and is independent evidence that antibody to HCV is present in the serum.…”

Imunoblot como teste suplementar para detecção de anticorpos contra o vírus da hepatite C em doadores de sangue

“…Este teste tem alta sensibilidade, detectando praticamente todos os portadores do vírus, além de indivíduos que foram infectados e não desenvolveram a infecção espontaneamente, tendo apenas anticorpos 6 . No entanto, em populações de baixo risco, como doadores de sangue e população geral, o teste tem baixo valor preditivo positivo, gerando exames falso-positivos em pessoas que nunca foram expostas ao vírus da hepatite C (VHC) 2 .…”

“…. Nos Estados Unidos, com o uso do RIBA, estima-se que 40% dos doadores com anti-VHC positivo por ELISA têm exames falso-positivos2 .No Brasil, o Ministério da Saúde não indica aos bancos de sangue que realizem qualquer investigação de doadores com anti-VHC por ELISA, recomendando que sejam encaminhados para atendimento médico 5 . Alguns bancos de sangue públicos das regiões mais desenvolvidas do país contam com técnicas sofisticadas de biologia molecular para detecção do material genômico do VHC.…”