Diagnosis of AIDS


Published on

AIDS continues to be important communicable disease.Optimal Diagnostic methods are a priority in Diagnosis..Errors in diagnosis can lead can be catostropic. consequences.

Published in: Health & Medicine
1 Comment
  • Fioricet is often prescribed for tension headaches caused by contractions of the muscles in the neck and shoulder area. Buy now from http://www.fioricetsupply.com and make a deal for you.
    Are you sure you want to  Yes  No
    Your message goes here
No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Diagnosis of AIDS

  1. 1. Diagnosis of AIDS Dr.T.V.Rao, MD.
  2. 2. AIDS A Global Concern <ul><li>TODAY THERE IS NO REGION OF THE WORLD UNTOUCHED BY PANDEMIC OF </li></ul><ul><li>AIDS </li></ul>
  3. 3. Majority of persons infected with HIV present with AIDS soon or later.
  4. 4. Why AIDS is more important TODAY <ul><li>Apart from Men, there is a increasing burden of Infections in Women. </li></ul><ul><li>Implication on Mother to Child Transmission </li></ul><ul><li>Female Adolescents are infected 3 - 6 </li></ul><ul><li>times higher than male counterparts. </li></ul><ul><li>AIDS has turned out to be Social </li></ul><ul><li>Problem. </li></ul>
  5. 5. Implication of AIDS <ul><li>Being diagnosed as having HIV/AIDS has life time repercussions. </li></ul><ul><li>Every body understands AIDS as a life threatening condition. </li></ul><ul><li>A casual way of dealing as being HIV + will have Moral, Legal, and Social consequences. </li></ul>
  6. 6. Prompt and Precise Diagnosis of AIDS make great impact on Humanity
  7. 7. Importance of precise Diagnosis of AIDS <ul><li>All patients should be informed about consequences of Testing for HIV infection, </li></ul><ul><li>Legality of respective National Laws should be followed. </li></ul><ul><li>A pretest and posttest counseling is Growing importance, even in Developing countries. </li></ul><ul><li>Today’s debate on testing for HIV status as matter of Health protocol ? </li></ul>
  8. 8. Counseling Improves the confidence
  9. 9. Purpose of Testing for HIV Infection <ul><li>A matter of great importance as in Blood donors to prevent infected blood being transfused. </li></ul><ul><li>To diagnose the patients infected with HIV virus. </li></ul><ul><li>For surveillance purpose. </li></ul><ul><li>Persons with high risk behavior. </li></ul><ul><li>In Pregnant women to prevent Mother to Child transmission. </li></ul><ul><li>Patient's presenting with opportunistic infections. </li></ul>
  10. 10. Diagnosis of HIV/ AIDS <ul><li>Basic Tests. </li></ul><ul><li>1.We can detect Antigen or Antibody </li></ul><ul><li>2.We can detect Antigen and Antibody. </li></ul><ul><li>3.Majority of Laboratories depend on Commercial Kits. </li></ul><ul><li>4.Devloped Nations going for Molecular and more precise Methods. </li></ul>
  11. 11. Screening Tests for HIV/AIDS Detection <ul><li>A screening test posses high Sensitivity </li></ul><ul><li>We rarely miss the Diagnosis in Infected patients. </li></ul><ul><li>Done as mass screening procedure. </li></ul><ul><li>Economical. </li></ul><ul><li>Developing countries depend on these tests even </li></ul><ul><li>for Diagnosis. </li></ul>
  12. 12. Confirmatory Tests in AIDS <ul><li>It is important to confirm all screening tests with Confirmatory tests, or we brand some one without infection as infected, </li></ul><ul><li>Confirmatory tests differentiates false reactive tests. and identifies truly infected or not. </li></ul>
  13. 13. Differences of Screening and Confirmatory Tests. <ul><li>Screening test </li></ul><ul><li>High degree of Sensitivity </li></ul><ul><li>Few false negatives </li></ul><ul><li>Confirmatory test </li></ul><ul><li>High degree of specificity </li></ul><ul><li>Few / No false positive </li></ul><ul><li>results. </li></ul>
  14. 14. Why patients should we tested with Screening and Confirmatory tests. <ul><li>Before you declare a person infected with HIV / AIDS you should perform both methods. </li></ul><ul><li>Faulty testing methods can lead to catastrophic consequences, and legal litigations. </li></ul>
  15. 15. Choosing Screening Testing methods <ul><li>Our aim to obtain 100 % specific results ? </li></ul><ul><li>But impossible. </li></ul><ul><li>As few may be infected and do not have sufficient antibodies to detect in the testing methods. </li></ul><ul><li>Depend on time tested methods. </li></ul><ul><li>Explore the reputation of the suppliers. </li></ul>
  16. 16. ELISA METHOD <ul><li>Universally accepted test ,most popular even in the developing nations. </li></ul><ul><li>Useful in large scale screening. </li></ul><ul><li>A common method used in Blood banks in mass screening of Human blood. </li></ul>
  17. 17. ELISA method – A ELISA plate
  18. 18. Sequence of Events in ELISA test
  19. 19. Different Methods of ELISA testing.
  20. 20. Why ELISA is very trust worthy. <ul><li>Easy to perform </li></ul><ul><li>Free from Radiation. </li></ul><ul><li>Relatively specific </li></ul><ul><li>Sensitive. </li></ul><ul><li>With scientific advances we have advanced to new generation of testing methods </li></ul><ul><li>Today we depend on 3 rd and 4 th generation ELISA methodologies. </li></ul>
  21. 21. Significance of ELISA <ul><li>Most reliable screening test for HIV infection. </li></ul><ul><li>50% of the infected will show positive reactivity in < 22 days. </li></ul><ul><li>95% show reactivity < 6 weeks </li></ul><ul><li>Sensitivity > 99.9 % </li></ul><ul><li>But needs confirmation with Western Blot. </li></ul>
  22. 22. Advances in ELISA Methods. <ul><li>1 st and 2 nd generation ELISA methods have become obsolete we have to switch to </li></ul><ul><li>Antigen sandwich ELISA protocols ( called as 3 rd generation ELISA ). </li></ul><ul><li>Many Nations have switched to 3 rd generation methods. </li></ul>
  23. 23. What is 3 rd Generation ELISA <ul><li>Helps in detection of early infections, </li></ul><ul><li>Can detect all classes of antibodies including Ig M </li></ul><ul><li>All isotypes of antibodies can be captured. </li></ul><ul><li>But proving to be expensive to developing Nations. </li></ul>
  24. 24. Need for 4 th Generation ELISA Methods The quest for better Diagnosis of AIDS continues
  25. 25. What is 4 th generation ELISA. <ul><li>A new generation Method in ELISA </li></ul><ul><li>Can detect both Antigen and Antibody in the same run ( in the same ELISA Plate ) </li></ul><ul><li>Helpful to make early diagnosis at least in few cases. </li></ul>
  26. 26. Determination of P 24 Antigen by ELISA <ul><li>Helps in the early detection of HIV infection. </li></ul><ul><li>Screening of Blood for HIV infection along with detection for antibody detection. </li></ul><ul><li>Early diagnosis of HIV infection in resource poor nations. </li></ul><ul><li>Monitoring Anti-retroviral therapy. But not a replacement for RNA quantization. </li></ul><ul><li>Even P 24 Antigens are subject of false positive results. </li></ul>
  27. 27. Limitation of Screening Tests. <ul><li>Imperfect Sensitivity, </li></ul><ul><li>Sensitivity to detect HIV2 ? </li></ul><ul><li>Failing to detect HIV variants. </li></ul><ul><li>Other technical errors. </li></ul>
  28. 28. Confirmatory Serological Tests All the Screening tests need to be confirmed before being declared as HIV infected.
  29. 29. Confirmatory Serological Tests. <ul><li>HIV Western Blots. </li></ul><ul><li>Line Immunoassay ( LIA ) </li></ul><ul><li>Immuno fluorescent Assay ( IFA ) </li></ul><ul><li>Utility is limited due technical and economical reasons </li></ul>
  30. 30. WESTEN BLOT TEST <ul><li>A Gold standard confirmatory test. </li></ul><ul><li>When tested combined with ELISA specificity is > 99.9 %. </li></ul>
  31. 31. Relation of HIV structure and Western Blot configuration
  32. 32. Principle of Western Blot <ul><li>HIV viral antigens are separated as; </li></ul><ul><li>gp160,gp120,p66,p55,p51,gp41,p31,p24, </li></ul><ul><li>p17, and p15. </li></ul><ul><li>Interpretation depends on presence / absence of reactivity to specific antigens. </li></ul>
  33. 33. Interpretation of Western Blot. <ul><li>The antibodies in the serum should react with at least two of following antigens, </li></ul><ul><li>gp 160/120 If does not meet </li></ul><ul><li>gp 41 requirements, marked </li></ul><ul><li>p 24 as indeterminate. </li></ul>
  34. 34. Negative Western Blot. <ul><li>Absence of any reactivity to the </li></ul><ul><li>bands is declared as Negative. </li></ul><ul><li>False positives are rare. </li></ul><ul><li>All doubtful results should be </li></ul><ul><li>reported as Negative. </li></ul>
  35. 35. Profile of Western Blot Test
  36. 36. Limitation of Western Blot Test <ul><li>If not designed for HIV 2 inclusion, we miss HIV2 infections, </li></ul><ul><li>Can give Indeterminate results in </li></ul><ul><li>Pregnancy </li></ul><ul><li>After administration of Tetanus </li></ul><ul><li>Toxoid. </li></ul><ul><li>Autoimmune conditions. </li></ul>
  37. 37. Rapid tests in the Diagnosis of AIDS <ul><li>A growing importance </li></ul><ul><li>Results can be issued within < 20 minutes. </li></ul><ul><li>Limited protocols, and less demanding technical skills. </li></ul><ul><li>But needs confirmation with ELISA / Western Blot testing. </li></ul><ul><li>Can differentiate HIV 1 and HIV 2. </li></ul>
  38. 38. Rapid Testing for AIDS with Dot Methods
  39. 39. Dot / Rapid Methods Useful <ul><li>In patients in Labor whose Immune status is not known, </li></ul><ul><li>Resource poor establishments. </li></ul><ul><li>But needs confirmation with ELISA / WB </li></ul>
  40. 40. Other supporting tests in AIDS Several tests will help in supporting to identify the progression of Disease.
  41. 41. Flowcytometry for Estimation of CD 4 lymphocytes
  42. 42. Use of CD 4 counts in Progress of AIDS <ul><li>CD 4 count measurements help for staging the diseases. </li></ul><ul><li>Flow cytometry has become the prominent tool in estimations of CD 4. </li></ul><ul><li>Specimens should be promptly processed. </li></ul>
  43. 43. Uses of Absolute CD4 Lymphocyte counts. <ul><li>Most widely used predictor of HIV progression. </li></ul><ul><li>Risk of progression to an AIDS defining illness, opportunistic infections or malignancy is high, when the counts drop below 200/mcl. </li></ul>
  44. 44. Uses of CD4 Lymphocyte percentage. <ul><li>Estimation of percentages is more useful than CD4 counts. </li></ul><ul><li>When the counts drops < 20% we have to watch for onset of opportunistic infections and malignancy. </li></ul>
  45. 45. Molecular Methods in Diagnosis of AIDS
  46. 46. Molecular Methods in Diagnosis of HIV / AIDS. <ul><li>1. The reverse transcription polymerase </li></ul><ul><li>chain reaction. </li></ul><ul><li>2. Nucleic acid sequence </li></ul><ul><li>amplification. ( NASBA ) </li></ul><ul><li>3. Branched chain DNA bDNA. </li></ul>
  47. 47. DNA –PCR ( RT-PCR) popular among Molecular Method
  48. 48. Polymerase Chain Reaction.-RT- PCR <ul><li>RT-PCR Need the use of Reverse transcriptase enzyme that converts RNA to DNA. </li></ul><ul><li>The testing is based on artificially replicating Nucleic acid sequence </li></ul><ul><li>of the target ( viral sequence ) so that </li></ul><ul><li>Millions to Billions are made available </li></ul><ul><li>for detection. </li></ul>
  49. 50. HIV Viral Load tests. <ul><li>The tests measure the amount of actively replicating HIV virus. </li></ul><ul><li>Correlates with response to antiretroviral drugs </li></ul><ul><li>Most helpful in diagnosis of HIV before Sero conversion. </li></ul><ul><li>False positives should be possible with low viremia < 500 copies. </li></ul>
  50. 51. Alternative Testing Media. From other Specimens. <ul><li>Saliva Detection of Ig G </li></ul><ul><li>Urine Detection of Ig G </li></ul><ul><li>Both ELISA and Western Blot </li></ul><ul><li>can be performed. </li></ul>
  51. 52. Reporting of all Positive results is a great concern, Avoid casual reporting
  52. 53. Post test counseling a Must in all Positive results
  53. 54. Precautions in HIV Testing. <ul><li>Casual testing to be curtailed. </li></ul><ul><li>To do with a purpose. </li></ul><ul><li>HIV positive result has Moral,social,and Economic consequences. </li></ul><ul><li>Post test counseling a must in all HIV+ individuals. </li></ul>
  54. 55. AIDS is <ul><li>Caused by fascinating Virus to - Scientists, </li></ul><ul><li>Friendly in approach to - Lovers. </li></ul><ul><li>Dangerous to Life to - Infected. </li></ul><ul><li>Dr.T.V.Rao,MD </li></ul>
  55. 56. STOP AIDS. <ul><li>Dr.T.V.Rao MD. </li></ul><ul><li>Professor of Microbiology </li></ul><ul><li>e mail [email_address] </li></ul>