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 - HIV 1/2 4.32 3.37
- HBV
- HTLV I/II
9.8
1.12
Current window period (in days): HCV HIV 23 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 - HGV E2 antibody - TT virus - CJD 1 - 3% 10% ?? ??
- 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