Epidemiology of Transfusion Transmitted Disease

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Epidemiology of Transfusion Transmitted
Disease Sharyn Orton, MT(ASCP)SBB, M.S.P.H,
Ph.D. candidate Project Leader, Transmissible
Diseases Department American Red Cross Jerome H.
Holland Laboratory Rockville, MD.
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After 20 years as a Medical Technologist in
the field of Blood Banking, I returned to
graduate school to pursue a Masters degree and
Ph.D in Epidemiology. This decision was a result
of my interests in both the burgeoning field of
new/emerging potentially transfusion transmitted
diseases and conditions as well as blood donor
behavior and modification. In order to be
competent to design and perform studies in these
areas, further education was needed. In addition,
there are very few formally trained
Epidemiologists in this field. My current
position as Project Leader in the Transmissible
Diseases Department has allowed me to develop and
coordinate research projects in the Blood Banking
arena. Some new areas of research include (1)
transfusion potential for infectious causes of
chronic diseases and cancer, (2) validation of
donor history questions, (3) donor motivations
and (4) application of new molecular techniques
for use in detection of transfusion transmitted
conditions. These are interesting and exciting
new areas of work.
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Each year - 8 million donors donate - 14 million
units of blood make - 23 million blood
components to - 4 million patients
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Safety measures - Volunteer blood supply -
Predonation educational material - Donor
history exam and questionnaire
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- Serological testing - Confidential Unit
Exclusion - Callback
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Tests performed on blood - ABO, Rh and antibody
screen - HBsAg - Anti-HBc - Anti-HCV
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- Anti-HTLV I/II - STS - Anti-HIV 1/2 - HIV p24
Antigen - ALT
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- Anti-CMV (selectively) - HCV RNA (new in
1999) - HIV RNA (new in 1999)
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Types of donations - Allogeneic - Directed -
Autologous - Apheresis
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Calculation of residual risk of transfusion
associated infection uses - seroconverting
donors to calculate incidence - the duration
of the window period
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Incidence in blood donors - HCV 4.32 - HIV
1/2 3.37 - HBV 9.8 - HTLV I/II 1.12
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Current window period (in days) HCV 23 HIV 11 HBV
59 HTLV 51
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Residual risk of transfusion transmitted
infection - HCV 2.72/million donations -
HIV 1.01/million donations - HBV 6.65/million
donations - HTLV 1.56/million donations
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Epidemiology of Hepatitis C -variation in
genotype prevalences worldwide -prior to
screening the blood supply caused hepatitis in
5- 10 of transfusion recipients
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- today causes hepatitis in 0.1 of
transfusion recipients
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Methods to Reduce Transfusion Transmitted
Infection - microbial inactivation - plasma
hold - leuko-reduction
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- minimizing exposure use of autologous
blood using strict transfusion criteria,
transfuse fewer products treat patient with
drugs
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- minimizing exposure, cond recombinant plasma
products
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Potential parasitic infections - malaria -
babesiosis - toxoplasmosis - Chagasdisease -
leishmaniasis
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Emerging viruses in transfusion - HGV - TTV -
prions CJD
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- KS associated HHV-8 - MS putatively associated
retrovirus
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Seroprevalence in blood donors - HGV RNA 1 -
3 - HGV E2 antibody 10 - TT virus ?? -
CJD ??
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- HHV-8 1 - 20 - MS associated retrovirus ??
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Additional thoughts - Clerical errors as a source
of transfusion transmission - New/emerging
agents and methods of surveillance - Blood
alternatives
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Comparative safety of transfusion Your risk of
violence or poisoning 1 3000 auto accident
1 8000 developing leukemia 1
12,000 homicide 1 100,000