The hepatitis C virus genotype and subtype frequency in hepatitis C virus RNA‐positive, hepatitis C virus antibody‐negative blood donors identified in the nucleic acid test screening program in Poland

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Abstract
BACKGROUND: Since 2002, blood donors in Poland have been tested not only for hepatitis C virus antibodies (anti‐HCV) but also for HCV RNA or HCV core antigen. This screening program identifies asymptomatic, recently infected individuals with no anti‐HCV (in the “window period”). The aim of this study was to compare HCV genotype and subtype distribution in window‐period (wp) donors, anti‐HCV‐positive donors, and chronic hepatitis C (CHC) patients.STUDY DESIGN AND METHODS: A total of 2.37 milion donors were investigated for HCV RNA, and 340,000 for HCV core antigen. HCV genotypes and subtypes were investigated in 50 HCV RNA‐positive, anti‐HCV‐negative donors; in 70 anti‐HCV‐positive donors; and in 170 CHC patients. Re‐questioning of wp donors for probable risk factors was introduced.RESULTS: HCV RNA was detected in 50 donors of 2.71 million (1:54,200) anti‐HCV‐negative blood donations. Of these 50 donors, 36 percent exhibited Subtype 1b, whereas Subtypes 3a and 4c/d were identified in 40 and 14 percent, respectively. In anti‐HCV‐positive donors and CHC patients, the frequency of Subtype 1b was significantly higher (75.7 and 85.3%, respectively); in both groups the lower frequency of Subtypes 3a (14.3 and 10.6%, respectively) and 4c/d (4.3 and 1.2%, respectively) was found. The probable source of infection was identified in 9 wp donors.CONCLUSIONS: The frequency of wp donors is 18.5 per 1 million. The unexpected high frequency of Genotype 4 and Subtype 3a and the low frequency of Subtype 1b was observed in wp donors compared to anti‐HCV‐positive individuals. Additional epidemiologic questioning introduced after HCV RNA detection may help to identify infection source.