[Prevalence of anti C100-3 and HBsAg in blood donors--comparative study of total collected blood units, total collection adjusted to exclude repeat blood donations, and in first time blood donors].

: Prevalence of anti C100-3 and HBsAg in donor blood collected at the Hiroshima Red Cross Blood Center during the period of Aug., 1990 to July, 1991 was studied in three groups--total received blood units (187,532 units) without any adjustment, blood units after adjustment by excluding repeat donations of blood units by the same donors (142,160 units), and blood units of first time donors (28,596 units). The results of the study is summarized as follows. 1) There was no significant difference in the prevalence of anti C100-3 between the group comprising the total collected units, and the group after the adjustment. This result suggests that repeat donors do not necessarily belong to any fixed age group. 2) The prevalence of HBsAg is significantly higher in the first time donor group than in the other two groups. In both the total blood units group and the group after the adjustment, prevalence of HBsAg among older age groups was as low as that of younger age groups. This is presumably because of the introduction of selective exclusion of HBsAg positive subjects from donors since 1980. When data from blood donors are used for the epidemiological studies of viral infection among healthy subjects, it is important to know the characteristics of such donor subjects and whether or not they are pre-screened for the viral markers in question.