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BLOOD SCREENING :AntiHBc and NAT-Necessity or Luxury


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BLOOD SCREENING :AntiHBc and NAT-Necessity or Luxury

  1. 2. By Brig Muhammad Ayyub MBBS, Ph.D (London) FRC Path (London) Professor of Haematology Commandant Armed Forces Institute of Transfusion Rawalpindi BLOOD SCREENING :AntiHBc and NAT-Necessity or Luxury
  2. 3. <ul><li>Transfusion of blood and blood products is an essential part of health care for patients deficient in one or more blood components. Therefore, organization of blood transfusion services must be based on a national blood policy, including relevant legislation, rules and regulations, which in turn must be an integral part of any national health policy </li></ul>
  3. 4. Historical perspective <ul><li>Pre-1985: syphilis, HBsAg </li></ul><ul><li>1985-1989: better HBsAg, HIV, HTLV, </li></ul><ul><li>+ ALT, anti-HBc (surrogates for nonA, nonB Hep) </li></ul><ul><li>1990: added HCV, HIV-2, HTLV-II </li></ul><ul><li>1996: HIV p24 Ag testing </li></ul><ul><li>1999: HIV, HCV NAT </li></ul><ul><li>2004: WNV NAT </li></ul>
  4. 5. Microbial Testing in England and North Wales <ul><li>HIV ELISA (combined HIV 1 Ag plus anti HIV 1 , and anti- HIV 2 ) </li></ul><ul><li>HBV HBsAg ELISA </li></ul><ul><li>HCV Anti-HCV ELISA plus NAT on pools of 48 samples </li></ul><ul><li>HTLV Anti-HTLV ELISA (on pools of 48 samples) </li></ul><ul><li>CMV Anti CMV for immunosuppressed recipients only. </li></ul><ul><li>Malaria Antibody screening of potentially exposed donors </li></ul><ul><li>Bacteria All donations are tested for antibody to syphilis; the option to test platelet preparations by culture methods is under review. </li></ul>
  5. 6. Residual Microbial Risk of Allogeneic blood transfusion <ul><li>HIV 1 in 8 million </li></ul><ul><li>HBV 1 in 1 million </li></ul><ul><li>HCV 1 in 30 million </li></ul><ul><li>Haemovigilance reports in the UK Serious Hazards of Transfusion (SHOT) </li></ul>
  6. 7. Risk of Transfusion- transmitted Infection (Italy) <ul><li>HIV 1 in 2,000,000 </li></ul><ul><li>Hepatitis C 1 in 2,000,000 </li></ul><ul><li>Hepatitis B 1 in 175,000 </li></ul><ul><li>Hepatitis A Rare </li></ul><ul><li>HTLV I/II 1 in 3,000,000 </li></ul><ul><li>Bacteria 1/3,000 (for platelets) </li></ul><ul><li>Malaria, T Cruzi, Babesia, Yersinia, Syphilis, Lyme, CJD, West Nile Virus…?? </li></ul>
  8. 9. Transfusion transmission risks HIV HBV HCV 1996 1994 1992 1990 1988 1986 1984 1:100 1:1000 1:10 000 1:100 000 1:1 000 000 1998 2000 Transmission risk, per unit 2002
  9. 10. Residual risk of transfusion-transmitted viral infections <ul><li>Mostly related to the pre-seroconversion window period. </li></ul><ul><li>The probability of transmitting HCV through transfusion of screened blood is related to the length of the pre-seroconversion window phase and the incidence of HCV infection among donors. </li></ul><ul><li>The magnitude of residual risk may differ within countries depending on the sensitivity of the assays used for screening and on the level of HCV endemicity. </li></ul>
  10. 11. New Discoveries Have Vastly Improved Blood Safety <ul><li>Up to 1 in every 100 blood units transmitted HIV or hepatitis C virus (HCV) </li></ul>1980s <ul><li>Standard serologic testing </li></ul><ul><ul><li>HIV transmission risk: 1 in 1.5 million </li></ul></ul><ul><ul><li>HCV transmission risk: 1 in 276,000 </li></ul></ul><ul><li>Nucleic Acid-Amplification Testing (NAT) </li></ul><ul><ul><li>Screens donors for HCV and HIV RNA </li></ul></ul><ul><ul><li>Eliminates problems with “window period” </li></ul></ul><ul><ul><li>HIV and HCV transmission risk: 1 in 2 million </li></ul></ul>Today Window Period Serologic Testing NAT HIV-1 22 days 11 days HCV 70 days 10 days Sources: Busch MP, Kleinman SH, Nemo GJ. Current and emerging infectious risks of blood transfusions. JAMA . 2003;289:959-962. Goodman JL. The safety and availability of blood and tissues – progress and challenges. NEJM . 2004;351:819-821. Jackson BR, Busch MP, Stramer SL, AuBuchon JP. The cost-effectiveness of NAT for HIV, HCV, and HBV in whole-blood donations. Transfusion . 2003;43:721-729. Busch MP, Dodd RY. Nucleic acid amplification testing and blood safety: what is the paradigm? Transfusion . 2000:40:1157-1160. Cited in Busch MP, Kleinman SH, Nemo GJ.
  11. 12. Relevance of Blood Transfusion Safety Activities <ul><li>Approximately 90 million transfusions worldwide annually </li></ul><ul><li>31% of transfusions not screened for HIV, Hepatitis B or Hepatitis C </li></ul><ul><li>Most laboratory screening lapses occur in developing countries </li></ul><ul><li> Source: WHO, GDBS 2001 </li></ul>Source: WHO, GDBS 2001
  12. 13. Relevance of Blood Transfusion Safety Activities <ul><li>Annually, unsafe blood transfusions are estimated to be responsible for </li></ul><ul><ul><li>10,000 new HIV infections </li></ul></ul><ul><ul><li>78,000 new HBV infections </li></ul></ul><ul><ul><li>500,000 new HCV infections </li></ul></ul><ul><ul><ul><li>Source: WHO, GDBS 2001 </li></ul></ul></ul>
  13. 14. The Developing World Faces Special Challenges When It Comes to Blood Safety <ul><li>Lack of financial resources </li></ul><ul><li>Inadequate numbers of health care personnel </li></ul><ul><li>Underdeveloped health infrastructure </li></ul><ul><li>Competing national priorities </li></ul>Approximately 70% of the World’s Nations Do Not Have Policies in Place to Ensure A Safe Blood Supply Source: Klein HG. Will blood transfusions ever be safe enough? JAMA . 2000;284:238-240. 13 million donations a year are not tested for HIV or HCV -- Mostly in high-risk areas with pressing need for blood 25% of maternal deaths related to pregnancy in developing nations are due to blood loss
  14. 15. Research report Evaluation of blood bank practices in Karacki,Pakistan,and the govt response Stephen Ruby,Rafique Khanani et al . <ul><li>National legislation – Not working </li></ul><ul><li>50% blood bank facilities utilize paid donors </li></ul><ul><li>25% actively recruited volunteer blood donors </li></ul><ul><li>8% facilities inquired about drug abuse </li></ul><ul><li>None asked any question about high-risk sexual behavior </li></ul><ul><li>95% blood banks had equipment and reagents to screen HBsAg,55% could screen HIV and 25% HCV </li></ul><ul><li>Practices at most blood banks below WHO standard </li></ul>
  15. 16. Hepatitis B Virus
  16. 17. Geographic Distribution of Chronic HBV Infection HBsAg Prevalence  8% - High 2-7% - Intermediate <2% - Low
  17. 18. Acute Hepatitis B Virus Infection with Recovery Typical Serologic Course Weeks after Exposure Symptoms HBeAg anti-HBe Total anti-HBc IgM anti-HBc anti-HBs HBsAg 0 4 8 12 16 20 24 28 32 36 52 100 Titer
  18. 19. Screening results-AFIT HBsAg snd Anti-HCV 4.25 2.15 34538 2004 3.91 1.84 39312 2005 4.17 2.34 32136 2003 4.20 2.44 30124 2002 4.19 2.39 28745 2001 4.02 2.51 25824 2000 Anti-HCV Positive (%) HBsAg Positive (%) Total donors screened Year
  19. 20. AFIT study : Impact of Anti-HBc test in HBsAg Negative donors <ul><li>17% healthy donors are antiHBc positive </li></ul><ul><li>Out of 17% positive 75% are antiHBs positive as well (Immune) </li></ul><ul><li>Out of 17% positive 5% are HBV DNA positive ( Occult HBV infection) </li></ul><ul><li>Occult carriers can transmit HBV infection in recipients </li></ul><ul><li>Residual risk of transmission of HBV infection can be reduced further by adding antiHBc test to the list of screening tests </li></ul>Article published in Transfusion and available online December 2006
  20. 21. NAT- Nucleic Acid Test- Evaluation as screening test in our setup AFIT on-going study <ul><li>500 Anti HCV negative sera have so far been tested for HCV RNA by real time PCR </li></ul><ul><li>Pool of 10 are tested along with appropriate controls </li></ul><ul><li>So far all AntiHCV negative are RNA negative as well </li></ul><ul><li>Study being carried out to evaluate prospects of NAT for HCV infection in our set-up </li></ul>
  21. 22. Conclusion <ul><li>Anti HBc and NAT are currently being employed by some industrialized nations for screening of blood donors. These countries have an excellent infrastructure and required legislations in place. They have reached this through a process of evolution. </li></ul><ul><li>In our setup we need to build a robust infrastructure and implement viable legislations </li></ul><ul><li>The financial implications definitely play an important role in blood and blood products screening policy. </li></ul>