title: Viremia levels in hepatitis C infection among Egyptian blood donors and implications for transmission risk with different screening scenarios.
abstract: BACKGROUND
  Knowledge about the viral load (VL) distributions in different stages of hepatitis C virus (HCV) infection is essential to compare the efficacy of serologic screening and nucleic acid testing (NAT) in preventing transfusion transmission risk. We studied HCV-RNA levels in Egyptian blood donors in the preseroconversion window period (WP) and in later anti-HCV-positive stages of infection.
  
  
  METHODS
  Subsets of individual-donation (ID)-NAT and anti-HCV-yield samples from a screening study among 119,756 donors were tested for VL by quantitative polymerase chain reaction (qPCR). Low viremia levels below the quantification limit of qPCR were determined by probit analysis using the proportion of reactive results on replicate NATs. Poisson distribution statistics were used to estimate transmission risk in different stages of HCV infection based on 50% minimum infectious doses (MID50 ) of 3.2 (1-10) and 316 (100-1000) virions in the absence and presence of anti-HCV, respectively.
  
  
  RESULTS
  Rates of total HCV infections and WP-NAT-yield donations in two Egyptian blood centers varied between 2.6% to 4.5% and 1:3100 to 1:9500, respectively. VLs ranged from 82 to 3 × 10(7) copies/mL in WP and from fewer than 1600 to 1.6 × 10(6) copies/mL in anti-HCV-positive carrier donations. Only two (1.1%) of 175 donors with probable resolved infection had detectable RNA on replicate testing (estimated VLs of 0.5 and 1.8 copies/mL). This translates to an estimated transmission risk of 0.028% if ID-NAT-nonreactive, anti-HCV-positive donations would be used for RBC transfusions.
  
  
  CONCLUSIONS
  Almost 99% of anti-HCV-reactive donations without detectable HCV-RNA on initial ID-NAT screening had eradicated the virus from the circulation, while 1% had extremely low VLs and are likely not infectious. The incremental safety offered by serologic testing of ID-NAT-screened blood seems minimal.
authors.affiliation: Shabrawishi Hospital, Dokki.
authors.forename: Magdy
authors.initials: M
authors.lastname: El Ekiaby
authors.affiliation: National Blood Transfusion Center, Cairo, Egypt.
authors.forename: Faten
authors.initials: F
authors.lastname: Moftah
authors.affiliation: National Blood Transfusion Center, Cairo, Egypt.
authors.forename: Heidi
authors.initials: H
authors.lastname: Goubran
authors.affiliation: Biologicals Quality Control, Rijswijk, the Netherlands.
authors.forename: Harry
authors.initials: H
authors.lastname: van Drimmelen
authors.affiliation: Institut National de Transfusion d Sang, Paris, France.
authors.forename: Syria
authors.initials: S
authors.lastname: LaPerche
authors.affiliation: University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Steve
authors.initials: S
authors.lastname: Kleinman
authors.affiliation: Blood Systems Research Institute, San Francisco, California.
authors.forename: Michael
authors.initials: M
authors.lastname: Busch
authors.affiliation: Lelie Research, Paris, France.
authors.forename: Nico
authors.initials: N
authors.lastname: Lelie
mesh_terms: D000328:Adult; D000465:Algorithms; D001782:Blood Donors / Q000706:statistics & numerical data*; D058731:Blood Safety; D046148:Donor Selection / Q000379:methods*; D004534:Egypt / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D006526:Hepatitis C / Q000097:blood / Q000453:epidemiology* / Q000635:transmission; D018937:Hepatitis C Antibodies / Q000097:blood; D006801:Humans; D008163:Luminescent Measurements; D008297:Male; D021141:Nucleic Acid Amplification Techniques; D015995:Prevalence; D012367:RNA, Viral / Q000097:blood*; D012306:Risk; D019562:Viral Load; D014766:Viremia / Q000453:epidemiology*
chemical_list: D018937:Hepatitis C Antibodies; D012367:RNA, Viral