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Implementing Rapid HIV Testing in the United States

Implementing Rapid HIV Testing in the United States. Overview and Background. Bernard M. Branson, M.D. Centers for Disease Control and Prevention. Questions: 1987. Should… persons attending STD clinics have a test for HIV antibody?

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Implementing Rapid HIV Testing in the United States

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  1. Implementing Rapid HIV Testingin the United States Overview and Background Bernard M. Branson, M.D. Centers for Disease Control and Prevention

  2. Questions: 1987 • Should… • persons attending STD clinics have a test for HIV antibody? • persons attending drug treatment programs have a test for HIV antibody? • the sexual partners of people with HIV infection be notified about their potential exposure and tested and counseled?

  3. Questions: 1987 • Should… • persons attending family planning services have a test for HIV antibody? • pregnant women have a test for HIV antibody as early in pregnancy as possible? • HIV antibody testing be a routine part of a premarital testing program? • Every patient admitted to a hospital be tested for HIV antibody?

  4. Questions: 1987 • How… • Can HIV antibody test results be used for appropriate medical and public health purposes without their being used for discrimination of social ostracism?

  5. 1989 Recommendation • No positive test results should be given to clients/patients until a screening test has been repeatedly reactive (i.e., two or more tests) on the same specimen, and a supplemental, more specific test such as the Western blot has been used to validate those results.

  6. Proportion of persons who do not return for their HIV test results Source: CDC Client Record Database, Publicly-funded HIV testing

  7. 8,023 27,947 1,374,709 1,442,847 708,220 26,465 1996 9,843 22,514 26,465 1,147,251 1,147,251 1,442,847 786,937 22,514 1997 9,843 22,514 26,465 1,091,045 1,147,251 1,442,847 856,876 1998 18,118 11,192 22,514 26,465 1,147,251 995,952 1,442,847 903,839 1999 16,048 10,593 22,514 26,465 1,028,274 1,147,251 1,442,847 913,057 2000 16,223 What if rapid HIV tests wereused in all public testing sites? 40,000 0 0 2,000,000 HIV Positive HIV Negative Current Strategy Current Strategy Additional, Rapid Test Additional, Rapid Test

  8. 1998 Recommendation • Health care workers should provide preliminary positive rapid test results before confirmatory results are available in situations where tested persons benefit.

  9. Interpreting Screening Test Results For a laboratory test: Sensitivity: Probability test=positive if patient=positive Specificity: Probability test=negative if patient=negative Predictive value: Probability patient=positive if test=positive Probability patient=negative if test=negative

  10. Example: Test 1,000 persons Test Specificity = 99.6% (4/1000) HIV prevalence = 10% True positive: 100 False positive: 4 Positive predictive value: 100/104 = 96%

  11. Example: Test 1,000 persons Test Specificity = 99.6% (4/1000) HIV prevalence = 10% True positive: 100 False positive: 4 Positive predictive value: 100/104 = 96% HIV prevalence = 0.4% True positive: 4 False positive: 4 Positive predictive value: 4/8 = 50%

  12. Predictive Value: Single Screening Test Test Specificity 99.8% HIV PrevalenceTrue +False +Predictive Value Positive 10% 100 2 98% 5% 50 2 96% 2% 20 2 91% 1% 10 2 83% 0.5% 5 2 71% 0.2% 2 2 50% 0.1% 1 2 33%

  13. Centrifuge to obtain serum or plasma

  14. Several reagent steps

  15. Blue color with reactive HIV test

  16. Principle: Flow-through devices Microparticles immobilized in membrane form test spots Control antibody: HIV-1 peptide • Anti-IgG • Anti-gold

  17. MedMira HIV 1-2

  18. Reconstitute Conjugate with buffer

  19. Add 1 drop buffer to cartridge

  20. Add 1 drop serum to cartridge

  21. Wash with buffer

  22. Add conjugate to cartridge; wash

  23. Positive Negative Read results immediately

  24. Immunochromatography • Lateral Flow Devices • Determine • Doublecheck • HemaStrip • OraQuick • Unigold

  25. Principle: Lateral flow devices Add Sample Control line Test Line Conjugate IgG Antibodies HIV antibodies Colloidal gold conjugated toHIV antigen HIV antigen Anti-IgG/gold antibodies

  26. Principle: Lateral flow devices •Specimen flows along the membrane and HIV antibodies(if present)bind to the HIV antigen conjugated to the colloidal gold forming a visible red band • The anti-IgG/gold antibodies at the control line bind to any unbound colloidal gold particles forming a visible red band.

  27. OraQuick: Oral fluid, serum, whole blood

  28. Obtain fingerstick blood specimen

  29. Specimen loop with 5 microliters blood

  30. Insert loop into vial and stir

  31. Insert paddle into vial

  32. Reactive Control Positive HIV-1 Positive Negative Read results in 20 minutes

  33. 2002 Consultation • How… • can we maximize the use of rapid HIV tests? • can we maintain reliable, accurate test results? • can we use rapid tests to reach people who have not been tested? • do we accomplish all of these goals with a moderate complexity rapid HIV test?

  34. Ken Bell Lisa Pealer Tracey Hodges Ed Johns Barbara Triggs Ann Shuttleworth Laura Coker Beatie Divine Kim Lindsey Marie Morgan Acknowledgements

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