Supplemental assays, such as recombinant immunoblot assays (RIBA), are used to confirm detection of antibodies to hepatitis C virus (HCV). However, due to their expense, they are not widely used in developing countries. The purpose of our study was to compare the results of second- and third-generation (G2 and G3, respectively) enzyme immunoassays (EIAs) and to resolve discordant results by using a supplemental assay to assess the reliability of G2 and G3 EIAs to confirm anti-HCV antibody-positive results. We performed both G2 and G3 EIAs for anti-HCV antibodies on 1,134 serum samples collected during the 2nd year of a longitudinal community-based study in Egypt; 35 samples with discordant results were tested by Abbott Laboratories Micro-Particle Immunoassay (M-EIA) and RIBA. Viremia was determined with an in-house nested reverse transcriptase PCR (RT-PCR) to detect HCV RNA. Concordance between the two assays (G2/G3) was 96.9%; 87 (7.7%) samples were positive and 1,012 (89.2%) were negative by both assays. For 17 samples, the discordant results were G2 assay negative and G3 assay positive, and for 18 samples, the discordant results were G2 assay positive and G3 assay negative. Among the 17 G2 assay-negative and G3 assay-positive samples, 15 were M-EIA positive and 7 were PCR positive. Among the 18 G2 assay-positive and G3 assay-negative samples, 2 were M-EIA positive and none were PCR positive. RIBA results from 24 discordant samples showed 87.5% agreement with the G3 EIA, 12.5% agreement with the G2 EIA, and 95.8% agreement with M-EIA. Eleven samples were indeterminate by RIBA and excluded from this analysis. Based on RIBA results, the sensitivity of the G3 EIA was 99%, compared to 89.8% for the G2 EIA, while the specificity of the G3 EIA was 99.8%, compared to 98.9% for the G2 EIA. These results show that the reliability of the G3 EIA in screening these sera is excellent, and the G3 assay can be used in the absence of supplemental tests where resources are limited. RIBA appears not to have advantages over the less expensive M-EIA screening assay. The main disadvantage of RIBA is the occurrence of indeterminate results, especially among problematic samples. Samples giving discordant results in multiple assays are often indeterminate with the RIBA.

This investigation's objective was to identify risk factors for hepatitis C virus (HCV) in a village in Upper Egypt with a moderately high prevalence (8.7%) of antibodies to HCV (anti-HCV). A representative sample of 6,012 (63%) of the 9,581 village inhabitants was included in the study. A questionnaire solicited information regarding risk factors for infection, and blood samples were tested for anti-HCV. Parenteral risks identified in age-adjusted analysis included blood transfusions, dental procedures, hospital admission, surgery, complicated deliveries, history of injection therapy for schistosomiasis, and history of frequent injections. Circumcision was pervasive and was not associated per se with ant-HCV; however, circumcision by an informal, rather than formal, health care provider was associated with anti-HCV among young men and boys. The results did not reveal any unique community-acquired exposures that caused HCV infections: inhabitants who had tattoos, who smoked goza, who were shaved by a community barber, or who had their ears pierced were not at greater risk for anti-HCV than those who did not. Risks identified in multivariate analysis for both those older and younger than 30 years included prior parenteral therapy for schistosomiasis and blood transfusion; for those 30 or younger, circumcision by an informal rather than formal health care provider, and frequent injections; and for those older than 30, never attending college, invasive medical procedures, and complicated deliveries. Selecting for those with blood transfusion, prior parenteral therapy for schistosomiasis, and invasive medical procedures would identify less than half of those infected. Inclusion of frequent injections would identify 80% of those infected with HCV, but as a result of the pervasive use of injections, it would not discriminate from those uninfected. Nonetheless, general reduction of these exposures and assuring sterile practices are logical goals for intervention.