The American Red Cross collects blood from a number of defined subsets of the donor population and the proportion of blood collected from each subset varies widely from center to center. A large part of the variation in prevalence of HBsAg may be related to variations in the proportion of blood collected from plants and factories, military units and schools or colleges. We have derived a regression equation, significant at the p˂0.001 level, which links HBsAg prevalence with these collection parameters. Using this equation, we were able to predict the prevalence of HBsAg among first-time donors in 6 of the 9 geographic divisions of the United States with an accuracy exceeding 10%. The predictions for the remaining divisions were within 35% of the actual value. Correlation studies were supported by measurements of true donor prevalence in three blood centers.
During the year 1978 this labciatory evaluated the specificity of all samples found reactive for hepatitis B surface antigen (HBsAg) by 44 of 57 regions of the American Red Cross Blood Services. Radioimmunoassay detected a total of 1,921 HBsAg-reactive samples among more than three million donor units tested. A vast majority (96%) of the samples had high level of HBsAg (≥20 ng/ml). Only about 50% of the samples with low level of HBsAg (<20ng/ml) were reactive in reversed passive hemagglutination. There were 13 samples that were repeatably reactive for HBsAg but were considered nonspecific as they were nonneutralizable in radioimmunoassay, 2 donors who showed nonspecific reactivity were further tested and it was found that the reactivity in radioimmunoassay persisted for more than 9 months, and this reactivity was also detectable by a second commercial kit for HBsAg. Antibodies to core and surface antigen were not found in any of the nine samples that were tested. The explanation of this nonspecific reactivity is unclear, but the data suggest that the nonspecific factor(s) may be an inherent property of the sample rather than a deficiency of the test reagents.
A new antigenic specificity for HBsAg is described, and its usefulness as an epidemiological marker is discussed. This specificity, l , was found in specimens from all geographic areas studied (United States, Latin America, South Africa, the Solomon Islands, and New Guinea). In these areas, l was strongly associated with HBsAg/ay; y-positive, l-negative samples were observed only among specimens from United States volunteer blood donors. This determinant allowed a distinction of HBsAg/ad classes. Thus, the l determinant was detected in 51.4% of HBsAg/adw4, 44.1% of HBsAg/adw(non-w4), and 50% of HBsAg/adr. The association of l and other HBsAg determinants with HBeAg or anti-HBe was also investigated. HBeAg was found to be associated with the presence of the l determinant and with the r determinant. Anti-HBe was associated with the presence of the d and w determinants and with the absence of the l specificity.
The present study was undertaken to determine whether there were any differences in the distribution of hepatitis B virus-(HBV) associated serologic markers among hepatitis B surface antigen-(HBsAg) positive first-time and repeat blood donors. The markers examined in samples from 412 newly identified HBsAg-positive donors (254 first-time and 158 repeat) included HBsAg titer and subtype, HBeAg/anti-HBe, and anti-HBc. Repeat donors were more frequently HBeAg-positive (25.9%) than were first-time donors (17.7%). Anti-HBc and anti-HBe were observed more often among first-time (99.6 and 76%) than repeat (91.8 and 60.8%) donors. No differences were found in the mean HBsAg titer nor in the subtype distribution in the two populations. The frequency of HBeAg positivity and the mean HBsAg titer in blood were significantly lower among first-time donors aged 30 or older as compared to those younger than 30. Such age-related tendencies did not occur among the repeat donors. The profiles of HBV markers suggest that the HBsAg-positive first-time donor group consists predominantly of long-term HBsAg carriers who may have acquired HBV at an early age, while the HBsAg-positive repeat donors have newly acquired infections.
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