HIV Guideline Sakchai Dettrairat

Transcription

1 HIV Guideline 2016 Sakchai Dettrairat Division of Clinical Immunology Department of Medical Technology Faculty of Associated Medical Sciences Chiang Mai University

2 Appearance of HIV markers in early HIV infection J Clin Virol, Volume 54, Issue 1, May 2012, p42-47

3 Diagnosis of HIV Infection Objectives Blood and blood products safety. Screening of donors of sperms, organs and tissues. Diagnosis of HIV infection in clinically suspected cases. Voluntary counseling and testing (VCT). Epidemiological surveillance. Research and surveys.

4 HIV Testing Diagnostic Tests Anti-HIV Antibody Test HIV p24 Antigen Test HIV Nucleic Acid Amplification Tests (NAAT) Screening Tests EIA/ELISA or CIAs Simple/Rapid Tests Confirmatory or Supplemental Tests WB IFA

5 Generation of anti-hiv EIAs Generation Antigens/antibodies Comment/characteristic First Antigens from HIV lysates Lack of sensitivity and specificity Second Third Fourth Recombinant proteins and/or synthetic peptides Use labeled antigen as conjugate Detection of both HIV antigen (p24) and Ab Improved sensitivity and production of combined HIV-1/HIV-2 assays Very high sensitivity and able to detect IgM Ab; reduced the window period considerably Further reducing the window period

6 Third generation Double Antigen Sandwich ELISA for detection of HIV Abs Enzyme conjugated HIV Ag IgG Ab Substrate E E Reactive End Product (color/light) E E E E IgM Ab rhiv Ag and synthetic peptides Env/Core Ags

7 Fourth generation Sandwich ELISA for detection of both HIV Ag and Abs Enzyme conjugated HIV Ag E E E Anti-HIV Ab Substrate E Reactive End Product (color/light) Enzyme-conjugated Anti-p24 Ab E E p24 Ag rhiv Ag/ peptide Anti-p24 Ab

8 Rapid HIV Tests Qualitative test to detect Abs to HIV-1/2 Simple or Moderate Complexity Serum/Plasma/Whole blood Visual Reading in min Testing formats Immunofilteration (flow through) Immunochromatography (lateral flow) Dot immunoassay, Particle agglutination Lateral flow strip

9 HIV Immunochromatographic Test (Lateral Flow Strip)

10 Sensitivity and Specificity of HIV tests Tests for screening of blood and blood products Sensitivity 100% Specificity > 99.5% Tests for individual diagnosis Sensitivity > 99.5% Specificity > 99%

11 Sensitivity & Specificity Diagnostic Sensitivity The ability of the test to identify correctly those who have the disease Diagnostic Specificity The ability of the test to identify correctly those who do not have the disease

12 Test Parameter

13 Interpreting HIV Test Results

14 PPV & Prevalence Assay 1 Assay 2 Assays 1+2 (in sequence) Sensitivity 99.0% 99.0% Specificity 99.5% 99.9% Prevalence PPV PPV PPV 0.2% 28.4% 66.4% 99.75% 2.0% 80.2% 80.2% 99.97% 20.0% 98.0% 99.6% 99.99%

15 PPV & NPV of HIV Testing Positive results Negative results Prevalence 0.82% HIV Infection No HIV Infection , , ,918 Sensitivity = 99.5%, Specificity = 99% PPV = 81.59/ = % NPV = 9,818.82/9, = >99.99% 10,000 (population)

16 PPV and NPV of HIV Testing Strategies at Different Prevalence Rates Prevalence (%) %PPV: 1 test %PPV: 2 tests %PPV: 3 tests %NPV

17 HIV Testing Strategies/Algorithms UNAIDS and WHO Recommended Alternative HIV Testing Strategies (1997) Thailand HIV Testing Algorithms (2013) CDC Laboratory testing for the Diagnosis of HIV Infection: Updated Recommendation (2014) WHO New Guidelines on HIV Testing (2015) Thailand Update Guideline for HIV Testing (2016)

18 Thailand HIV testing algorithm for individual diagnosis (2013) Tests for individual diagnosis Sensitivity > 99.5% Specificity > 99% hp?option=com_content&view=ar ticle&id=79&itemid=86

19 HIV testing Algorithms in Adults and Children >18 M A1 A1- (NR) A1+ (R) Repeat A1 and A2 A2 A1+, A2- A1+, A2+ A1-, A2- A1+, A2- A1+, A2+ Anti-HIV negative A1+, A2+, A3- A3 A1+, A2+, A3+ Inconclusive Retest at 2 weeks and/or 1 month and 3 months Anti-HIV Positive Retest sample 2

20 HIV testing Algorithms in Children <18 M

21 Published June 27, v/pdf/hivtestingalgori thmrecommendation- Final.pdf

22 Recommended Laboratory HIV Testing Algorithm for Serum or Plasma Specimens

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24 The recommended algorithm has several advantages More accurate laboratory diagnosis of acute HIV-1 infection, Equally accurate laboratory diagnosis of established HIV-1 infection, more accurate laboratory diagnosis of HIV-2 infection, fewer indeterminate results, and Faster turnaround time for most test results.

25 WHO New Guidelines on HIV Testing (2015)

26 1/ _eng.pdf?ua=1&ua=1

27 Testing strategy for HIV diagnosis in high prevalence settings ( 5%) HIV inconclusive 1. A1+A2-A3+ or 2. A1+A2-A3- If A1 is 4 th gen assay Retest in 14 days

28 Testing strategy for HIV diagnosis in low prevalence settings (<5%) HIV inconclusive 1. A1+A2+A3- or 2. A1+A2- If A1 is 4 th gen assay Retest in 14 days

29 When to retest? WHO recommends retesting to assure accurate diagnosis in three instances: 1. retesting people who test HIV-negative but are at on-going risk for HIV; 2. retesting people with an HIV inconclusive status after 14 days; and 3. retesting to verify an HIV-positive diagnosis before enrolling in care and/or starting antiretroviral therapy (ART)

30 Thailand Update Guideline for HIV Testing (2016)?

31 HIV testing Algorithms in Adults and Children >24 Months Inconclusive: Retest at 2 weeks and 1 month

32 HIV testing Algorithms in Children <24 Months

33 No diagnostic test or algorithm can be completely accurate in all cases of HIV infection.