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HIV Diagnosis, Acute Infection and Superinfection
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  1. HIV Diagnosis, Acute Infection and Superinfection Don Kurtyka, ARNP, MS, MBA University of South Florida College of MedicineTampa General HospitalHillsborough County Health Department

  2. Objectives • Discuss the diagnosis of HIV and available tests • Describe the approach to the diagnosis of acute retroviral syndrome • Debate the advantages and disadvantages of early treatment of acute HIV infection • Discuss the evidence for the possibility of superinfection / reinfection and the implications for patient education and management

  3. Anonymous vs Confidential • Anonymous • Identifying information not provided • Results not linked to identifying information • Allows reporting of HIV infection without breaching confidentiality • Disadvantage: may not be able to locate clients for test results • Confidential • Clients linked to test result by identifying information • Results remain confidential • Informed consent

  4. Pre-Test Counseling • Goal: reduce HIV acquisition and transmission • Accurate and current information about HIV • Obtain informed consent • Transmission and acquisition • HIV test info: risk, benefits, meaning of potential test results • Assessment of individuals risks and appropriate risk reduction activities • Capacity to comprehend HIV testing and consent

  5. Post-Test Counseling • Accurate and current information about HIV • Local resources • Risk reduction education • Referrals for ongoing care and support • Healthy living strategies • Meaning of test results and state reporting guidelines • Mental health support / counseling

  6. Diagnosis of HIV Infection • Viral antibodies • Viral antigens • Viral RNA/DNA • Culture Lancet, 1996; 348: 176.

  7. Enzyme ImmunoassayEnzyme-Linked Immunosorbent Assay(EIA, ELISA) • Primary HIV antibody screening test • Serum plasma, dried blood spots, oral fluids, urine • HIV-1/2, HIV-1, HIV-2 • High degree sensitivity and specificity • Repeatedly reactive: confirmatory testing

  8. Negative Antibody Test Results • HIV negative • Recent infection: too early for seroconversion • CDC: follow-up testing at 6 weeks, 12 weeks, 6 months

  9. Confirmation Process • Non-negative screenings should be confirmed • Western Blot (WB) • Immunofluorescent Antibody Assay (IFA) • Higher specificity than EIA • Interpretation can be subjective

  10. Predictive Value: HIV Ab Tests • Depends on the prevalence of HIV infection in the population • Low HIV prevalence: predictive value of a positive test is low • HIV Ab testing of low prevalence populations likely to produce more false-positive than true-positive results

  11. Window Period • Time delay from infection to positive EIA • Average: 10-22 days • Most seroconvert within six months Am J Med 2000; 109

  12. HIV-1 vs HIV-2 • HIV-1: Most cases • Group M: predominant strain world-wide • Subtypes (clades): A to K, N, O • Clade B • US and Europe • 98% of HIV-1 in US • Most non-B subtypes were acquired outside US • Clade C: Southeast Asia • N (“new”): 1998 • Group O: West Africa • Recombination between viruses of different clades becoming more common

  13. Predominant HIV-1 Subtypes • A: West/East/Central Africa, East Europe, Mideast • B: North America, Europe, Mideast, East Asia, Latin America • C: South Africa, South Asia, Ethiopia • D: East Africa • E: Southeast Asia JAIDS 2002; 29:184

  14. HIV-2 • Primarily found in West Africa • Causes immune deficiency due to depletion of CD4 cells • 5-8 fold less efficient transmission compared to HIV-1 • Associated with lower viral load • Slower rate of CD4 decline and clinical progression • Negative Ab tests in 20-30% depending on EIA assay • WB: not well standardized nor FDA approved Bartlett, JG 2003: Medical Management of HIV Infection, p5.

  15. Testing Recommendations: HIV-2 • Natives of endemic areas • Needle-sharing and sex partners of persons from endemic areas • Sex or needle-sharing partners of persons with known HIV-2 infection • Transfusion or non-sterile injection recipients in endemic areas • Children of HIV-2 infected women

  16. Benin Burkina Faso Cape Verde Cote d’Ivoire Gambia Ghana Guinea Guinea-Bissau Liberia Mali Mauritania Niger Nigeria Sao Tome Senegal Sierrra Leone Togo HIV-2 Endemic Areas West Africa Other • Mozambique • Angola

  17. Confirmation Process: WB • Detects antibodies to HIV-1 proteins • Core: p17, p24, p55 • Polymerase: p31, p51, p66 • Envelope: gp41, gp120, gp160 • Negative: no bands • Positive: • Reactivity to gp41 + gp120/160 or • Reactivity to p24+gp120/160 • Indeterminate: • EIA repeatedly reactive • Presence of any band pattern not meeting criteria for positive results

  18. False Negative Results • High-prevalence population: 0.3% • Low-prevalence: <0.001% • Usually due to testing during window period • Rare patients seroconvert in late-stage disease • Technical or clerical error • Type N or O • HIV-2

  19. False Positive Test Results • Much less common than in earlier times • Frequency: 0.0004% to 0.0007% • Causes • Autoantibodies (single case, Lupus, ESRD) • HIV vaccines • EIA+: 68% • WB+: 0-44% • Technical / clerical error NEJM 1988;319:961 Ann Intern Med 1989;110:617

  20. Indeterminate Results • 4-20% of WB assays with positive bands • Testing during seroconversion • p24 usually appears first • Late stage HIV: loss of core antibody • HIV vaccine recipients • Technical / clerical error • Infection with O strain or HIV-2

  21. Indeterminate Results (continued) • Cross-reacting nonspecific antibodies • Collagen-vascular disease • Autoimmune disease • Pregnancy • Organ transplantation • Lymphoma, other malignancies • Liver disease • Multiple sclerosis • Recent immunization

  22. Indeterminate Results • Evaluate HIV risk • Low risk: almost never infected with HIV-1 or HIV-2 • Repeat testing: often continued indeterminate • Cause: frequently not established • HIV unlikely • Follow-up serology in 3 months • Seroconversion: usually WB+ in 1 month • Repeat testing at 1, 2, 6 months • Counseling to reduce potential transmission

  23. Frequency of HIV Testing • High risk behavior: every 6-12 months • Annual seroconversion • General population: 0.02% • Military recruits: 0.04% • MSM: 0.5 - 2% • IDU in high prevalence area: 0.7-6%

  24. Alternative Testing • Home test kits • Rapid Testing • Alternative body fluids • Saliva • Urine • Vaginal secretions • Viral detection

  25. Home Testing • Home specimen collection • Self-dried blood spot obtained with lancet • Anonymous coding • Mail/courier to testing facility • Double EIA and confirmatory IFA/WB • Sensitivity/Specificity: ~100% • Results relayed to user by telephone after user initiates request • Negative: prerecorded message • Positive: live conversation and counseling

  26. Rapid HIV Antibody Detection • Results in 15-20 minutes • Occupational exposure • Women in labor with unknown HIV status • Clients unlikely to return for visits • Outreach • ERs

  27. Rapid HIV Antibody Detection • OraQuick HIV-1 Antibody Test (OraSure) • Results read by provider in 20 minutes • Sensitivity: 99.6% / Specificity: 100% • $20-30 • Testing initially delayed due to CLIA requirements • Fingerstick sample of blood • Negative test: definitive • Positive test: needs standard serology confirmation • Not recommended for HIV-2 screening

  28. Rapid HIV Antibody Detection • Single Use Diagnostic System (SUDS) HIV-1 Test • Venipuncture • Results: 15-30 minutes • Confirmatory WB required • Double Check (Organies)

  29. Type N, Type O, HIV-2 • EIA may fail to detect O subtype • N group: causes false-negative EIA but may be WB positive • HIV-2: false negative EIA in 20-30% • Consider specific HIV-2 testing

  30. P24 Antigen • Part of blood bank algorithms since 1996 • Uncommon in clinical practice • Detects free, non-complex HIV antigens in peripheral blood

  31. Typical Course of Primary HIV 1 mil HIV RNA 100,000 + HIV RNA HIV-1 Antibodies _ 10,000 Ab P24 + 1,000 Exposure 100 Symptoms 10 0 20 30 40 50 Days

  32. Rapid Test Results • Reactive (preliminary positive) rapid test • Screening test is positive • Preliminary result • Confirmatory testing required • Precautions to avoid viral transmission • Negative rapid test • No recent exposure: definitive negative • Possible recent exposure: • Recommend re-test • Counseling to prevent transmission

  33. OraQuick: Florida DOH • 6 Month Pilot Studies • Hillsborough CHD • Duval County Jail • Orlando CBO for substance abuse • Miami: 2 sites • Key West: only anonymous site

  34. Saliva Testing: OraSure • EIA and WB to detect IgG • Specimen collection device, antibody screen, WB confirmation • Cost: ~$25 • Specially treated pad placed between lower cheek and gum for 2 minutes • Vial sent to lab for processing • Sensitivity and specificity comparable to standard serologic testing (~99.5%) • Advantages: ease of collection; low cost; improved patient acceptance • Disadvantage: client must return for results

  35. Urine Testing • Calypte HIV-1 Urine EIA • Positive results require standard serologic confirmation • Sensitivity: 99%; Specificity: 94% • Cost: ~$4

  36. Vaginal Secretions • IgG EIA • CDC: recommended for rape victims • Semen contains HIV IgG Ab

  37. Indications for HIV Viral Detection • Confusing / indeterminate serologic test results • Acute retroviral infection • Neonatal infection • Window period following exposure • Not FDA approved for diagnosis of HIV • Expensive

  38. Viral Detection • p24 Antigen • HIV-1 DNA PCR • Most sensitive: able to detect 1-10 copies of proviral DNA • S/S: 99% / 98% • HIV-1 RNA (RT-PCR, bDNA) • S/S: 95-98% • Viral culture of PBMC: expensive, labor intensive, reliability variable

  39. Viral Detection: HIV-2 • bDNA proficient at quantitation of many non-clade B viruses • Amplicor version 1.5 designed to detect other clades

  40. National RecommendationsFor HIV Testing ofPregnant Women • USPHS Recommendations for HIV Screening of Pregnant Women (4-22-03) • Universal testing for all pregnant women as a routine part of prenatal care using an “opt out” approach • Labor and Delivery: routine rapid testing if HIV status unknown • Postnatal: rapid testing for all infants whose mother’s status is unknown • Regulations, laws, and policies about HIV screening of pregnant women vary from state to state

  41. Acute HIV Infection

  42. Acute HIV Infection • Transient symptomatic illness in 40-90% • Usually mild but can be severe • 2-6 weeks after infection • Often not recognized by primary care clinicians • Symptoms non-specific • Often resembles influenza, mononucleosis • “Cold symptoms” absent • Can be asymptomatic • Duration: 14 days DHHS Guidelines July 14, 2003

  43. Acute HIV Infection Neuro: meningoencepalitis or aseptic meningitis; peripheral neuropathy or radiculopathy; facial palsy, Guillain-Barre syndrome; brachial neuritis; cognitive impairment or psychosis CDC 2002

  44. Rash in Acute HIV Infection • Trunk, face, extremities • Palms and soles rarely involved • 5-10 mm diameter • Erythematous, nonpruritic, painless

  45. Laboratory FindingsAcute HIV Infection • Lymphopenia  lymphocytosis • Atypical lymphocytes • Transient CD4 decline • VL: 100,000 – 1,000,000

  46. Diagnosis of Acute HIV Infection • Recognition of clinical symptoms • No true constellation of signs/sympoms • Presence of any symptom(s) • History of activity associated with HIV risk • Detectable plasma HIV RNA • Highly sensitive • False positive possible • Detectable p24 Antigen • Less sensitive • False positive rare

  47. Acute HIV Infection • High virus levels (105-106 copies/mL) • 2-9% of HIV-negative have false positive results • Usually associated with low RNA titers <10,000 • VL in new infections • Correlates with rate of CD4 decline • Prognostic indicator in early disease