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Hepatitis B virus transmission by blood transfusion during 4 years of individual‐donation nucleic acid testing in South Africa: estimated and observed window period risk
Author(s) -
Vermeulen Marion,
Dickens Caroline,
Lelie Nico,
Walker Evangelia,
Coleman Charl,
Keyter Mark,
Reddy Ravi,
Crookes Robert,
Kramvis Anna
Publication year - 2012
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1111/j.1537-2995.2011.03355.x
Subject(s) - window period , virology , hepatitis b virus , medicine , hepatitis b , transmission (telecommunications) , blood transfusion , antibody , nat , orthohepadnavirus , hepadnaviridae , virus , immunology , biology , serology , electrical engineering , engineering , computer network , computer science
BACKGROUND: Since October 2005, a total of 2,921,561 blood donations have been screened by the South African National Blood Service for hepatitis B virus (HBV) by individual‐donation nucleic acid testing (ID‐NAT). Over 4 years, 149 hepatitis B surface antigen–negative acute‐phase HBV NAT–positive donations were identified (1:19,608). The lookback program identified one probable HBV transmission. STUDY DESIGN AND METHODS: The complete genomes of HBV isolated from the donor and recipient were sequenced, cloned, and analyzed phylogenetically. The HBV window period (WP) transmission risk was estimated assuming a minimum infectious dose of 3.7 HBV virions and an incidence rate correction factor of 1.34 for transient detectability of HBV DNA. RESULTS: Of 149 acute‐phase HBV NAT yields, 114 (1:25,627) were classified as pre–antibody to hepatitis B core antigen (anti‐HBc) WP and 35 (1:83,473) as post–anti‐HBc WP. The acute‐phase transmission risk in the HBV DNA–negative pre‐ and post–anti‐HBc WPs (of 15.3 and 1.3 days, respectively) was estimated at 1:40,000 and 1:480,000, respectively. One HBV transmission (1:2,900,000) was identified in a patient who received a transfusion from an ID‐NAT–nonreactive donor in the pre–anti‐HBc WP. Sequence analysis confirmed transmission of HBV Subgenotype A1 with 99.7% nucleotide homology between donor and recipient strains. The viral burden in the infectious red blood cell unit was estimated at 32 (22‐43) HBV DNA copies/20 mL of plasma. CONCLUSION: We report the first known case of transfusion‐transmitted HBV infection by blood screened using ID‐NAT giving an observed HBV transmission rate of 0.34 per million. The estimated pre–acute‐phase transmission risk in the ID‐NAT screened donor population was 73‐fold higher than the observed WP transmission rate.