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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.
After 20+ years as a Medical Technologist in the field of Blood
Banking, I returned to graduate school to pursue a Master’s 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.
Each year:
- 8 million donors donate
- 14 million units of blood make
- 23 million blood components to
- 4 million patients
Safety measures:
- Volunteer blood supply
- Predonation educational
material
- Donor history exam and
questionnaire
- Serological testing
- Confidential Unit Exclusion
- Callback
Tests performed on blood:
- ABO, Rh and antibody screen
- HBsAg
- Anti-HBc
- Anti-HCV
- Anti-HTLV I/II
- STS
- Anti-HIV 1/2
- HIV p24 Antigen
- ALT
- Anti-CMV (selectively)
- HCV RNA (new in 1999)
- HIV RNA (new in 1999)
Types of donations:
- Allogeneic
- Directed
- Autologous
- Apheresis
Calculation of residual risk of
transfusion associated infection
uses:
- seroconverting donors to
calculate incidence
- the duration of the window
period
Incidence in blood donors:
- HCV
4.32
- HIV 1/2
3.37
- HBV
9.8
- HTLV I/II
1.12
Current window period (in days):
HCV
23
HIV
11
HBV
59
HTLV 51
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
Epidemiology of Hepatitis C
-variation in genotype
prevalences worldwide
-prior to screening the blood
supply caused hepatitis in 510% of transfusion
recipients
- today causes hepatitis in ~
0.1% of transfusion
recipients
Methods to Reduce Transfusion
Transmitted Infection
- microbial inactivation
- plasma hold
- leuko-reduction
- minimizing exposure:
use of autologous blood
using strict transfusion
criteria, transfuse fewer
products
treat patient with drugs
- minimizing exposure, con’d:
recombinant plasma
products
Potential parasitic infections
- malaria
- babesiosis
- toxoplasmosis
- Chagas’disease
- leishmaniasis
Emerging viruses in
transfusion:
- HGV
- TTV
- prions: CJD
- KS associated HHV-8
- MS putatively associated
retrovirus
Seroprevalence in blood
donors:
- HGV RNA
1 - 3%
- HGV E2 antibody
10%
- TT virus
??
- CJD
??
- HHV-8
1 - 20%
- MS associated retrovirus ??
Additional thoughts
- Clerical errors as a source of
transfusion transmission
- New/emerging agents and
methods of surveillance
- Blood alternatives
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