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Inputs to a case-based HIV surveillance syste m

Inputs to a case-based HIV surveillance syste m. Objectives. Review HIV case definitions Understand clinical and immunologic staging Identify the sentinel events in a case reporting system Identify existing data sources to report sentinel events. WHO Surveillance Case Definitions.

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Inputs to a case-based HIV surveillance syste m

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  1. Inputs to a case-based HIV surveillance system

  2. Objectives • Review HIV case definitions • Understand clinical and immunologic staging • Identify the sentinel events in a case reporting system • Identify existing data sources to report sentinel events

  3. WHO Surveillance Case Definitions

  4. Background • 2004 – 2005 • WHO regional meetings to revise guidelines • April 2006 • WHO global consensus meeting to finalize the revision of clinical stage and case definitions

  5. Case Definition: HIV Infection • Adults and children 18 months or older: • Positive HIV antibody testing (rapid or laboratory-based enzyme immunoassay) confirmed by a second HIV antibody test (rapid or laboratory-based enzyme immunoassay) relying on different antigens or of different operating characteristics. and /or; • Positive virological test for HIV or its components (HIV-RNA or HIV-DNA or ultrasensitive HIV p24 antigen) confirmed by a second virological test obtained from a separate determination. • Children younger than 18 months: • Positive virological test for HIV or its components (HIV-RNA or HIV-DNA or ultrasensitive HIV p24 antigen) confirmed by a second virological test obtained from a separate determination taken more than four weeks after birth. • Note: Positive antibody testing is not recommended for definitive or confirmatory diagnosis of HIV infection in children until 18 months of age.

  6. Case Definition:Advanced HIV Infection (including AIDS) • Adults and children with confirmed HIV infection: • Clinical criteria: • Presumptive or definitive diagnosis of any stage 3 or stage 4 condition • Immunological criteria: • CD4 count less than 350/mm of blood • Children younger than five years of age with confirmed HIV infection: • %CD4+ <30 among those younger than 12 months • %CD4+ <25 among those aged 12–35 months • %CD4+ <20 among those aged 36–59 months

  7. Primary HIV Infection • Definition: The time of HIV infection. Some clinical symptoms, but no (or few) antibodies present in blood • There is no standard case definition • This can be identified by recent appearance of HIV or by identifying viral products (HIV-RNA or HIV-DNA and/or ultrasensitive HIV p24 antigen) with negative (or weakly reactive) HIV antibody • If identified, this should be reported • Primary HIV Infection should not be confused with clinical staging conditions developed with established HIV infection

  8. WHO Clinical and Immunological Classification for HIV

  9. Purpose of Classification System • Classification is used to assess patients before they are put on treatment (presumptive and definitive diagnosis) • Proposed to use clinical staging events and immunologic classification to assess individuals once they are receiving ART

  10. WHO Clinical Classification of Established HIV Infection

  11. WHO Immunological Classification of Established HIV Infection

  12. WHO classifications

  13. HIV Case-Based Surveillance

  14. Review: WHO Surveillance System Recommendations • WHO now recommends that reporting be expanded to cover the entire spectrum of HIV disease. • Previous case definitions focused only on AIDS cases • WHO recommends that countries standardise their reporting practices. • Countries may: • Report all HIV cases (clinical stages1through 4) • Report advanced HIV disease (clinical stages 3 and 4) • Report AIDS cases (clinical stage 4)

  15. Pro and Cons of WHO Options • Report all HIV cases (clinical stages1through 4) • Pros: • Full picture of epidemic • Allows tracking of disease progression • Follow disease trends for both new infections and later stages • Identifies priority populations that may need additional surveillance activities and prevention services • Can be generalized to entire population • Cons: • Can be difficult to implement • Can be expensive

  16. Pro and Cons of WHO Options • Report advanced HIV disease (clinical stages 3 and 4) • Pros: • Measure of clinical burden • Those how are diagnosed with HIV and who need ART • Some disease trends • Cons: • Under-reporting • May increase even as prevention decreases new cases

  17. Pro and Cons of WHO Options • Report AIDS cases (clinical stage 4) • Pros: • Clinical burden • Easier to manage • Cons: • Under estimation of epidemic • Trends for AIDS cases may differ from new HIV infection

  18. Monitor HIV Disease HIV disease sentinel events HIV exposure (exposed infants or sexual transmission) HIV infection 1st positive HIV test 1st CD4 count 1st CD4count <350 1st viral load 1st CD4 <200 AIDS-related Opportunistic Infection Death

  19. Monitor HIV Disease HIV disease sentinel events HIV exposure (exposed infants or sexual transmission) HIV infection 1st positive HIV test 1st CD4 count 1st CD4count <350 AIDS reporting 1st viral load 1st CD4 <200 AIDS-related Opportunistic Infection Death

  20. Monitor HIV Disease HIV disease sentinel events HIV exposure (exposed infants or sexual transmission) HIV infection 1st positive HIV test 1st CD4 count 1st CD4count <350 HIV case reporting 1st viral load 1st CD4 <200 AIDS-related Opportunistic Infection Death

  21. Where Will the Data Come From? • HIV antibody test (positives only) – probably already exists in most countries • Laboratories, rapid testing from facilities • Clinical stages? Which ones? • HIV facility identifies clinical stage at first visit and reports it • All CD4 tests? • Labs • All Viral load tests? • Labs

  22. Data Flow for Case Surveillance

  23. All laboratories Health centres ART treatment clinics TB clinics VCT sites Private physicians Hospitals PMTCT programme Blood banks Hospice Vital statistics registries How Will Cases be Identified? Potential sources of HIV case reports:

  24. Thank You Working Together to Plan, Implement, and Use HIV Surveillance Systems

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