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TB Case finding/TB Prevention in HIV infected populations

TB Case finding/TB Prevention in HIV infected populations. Helen Ayles ZAMBART Project. Before HIV. --_-_--_-. 1 Infectious case. 2 cases of TB. 20 contacts. Stability. 1 Non-Infectious. With HIV (10%). --_-_--_-. 1.2 Infectious cases. 18 HIV-ve. 2 HIV+ve. 1.8 cases. 20 contacts.

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TB Case finding/TB Prevention in HIV infected populations

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  1. TB Case finding/TB Prevention in HIV infected populations Helen Ayles ZAMBART Project

  2. BeforeHIV --_-_--_- 1 Infectious case 2 cases of TB 20 contacts Stability 1 Non-Infectious

  3. WithHIV (10%) --_-_--_- 1.2 Infectious cases 18 HIV-ve 2 HIV+ve 1.8 cases 20 contacts 0.8 cases An Epidemic 1.4 Non-Infectious

  4. New Cases of Tuberculosis in Zambia Notification Rate /100,000 /year 1964-1996 Source NASTLP/MoH

  5. No country with a severe HIV epidemic is controlling TB

  6. Reduce prevalence of HIV WithHIV (10%) --_-_--_- Reduce transmission 1.1 Infectious cases 18 HIV-ve 2 HIV+ve 1.8 cases 20 contacts Reduce reactivation 0.8 cases An Epidemic 1.5 Non-Infectious

  7. How does TB impact on HIV • 750,000 PLHIV will develop TB this year • TB is one of the leading causes of death in PLHIV • ~200 PLHIV will die today of TB – despite the fact that TB is curable • ART reduces the rate of developing TB but PLHIV on ART still have a massively increased risk of developing TB (4-8x that of HIV negative)

  8. What can the HIV community do? • Find more cases of active TB and treat them earlier • Reduce reactivation of latent TB in those individuals who do not yet have active TB Both will prevent TB!

  9. TB Preventive therapy • Cochrane review of 11 randomised trials including 8,130 HIV positive participants showed an overall reduction in TB of 33% (RR 0.67, 95% CI 0.51-0.87), and a reduction of 62% (RR 0.38, 95% CI 0.25-0.57) in people with a positive TST • National and international policies exist to implement it Poor uptake of policy in high burden countries Woldehanna, Cochrane review 2004

  10. How? When? Where? Screen all HIV infected individuals for TB Active TB: Treat Latent TB: Prophylaxis No active Expected yield 0-6%1-4 Eligibility 10-50%5,6 1. Espinal, Lancet 1995, 2.Burgess, AIDS 2001, 3. Kimmerling, IJTLD 2002,4. Mohammed, IJTLD 2004, 5. Aisu, AIDS 1995, 6. Ayles Trop Doc 2006

  11. How to Screen for TB • Symptoms • Chest x-ray • Sputum examination: smear Vs culture Can use the same screens to EXCLUDE TB How to Screen for Latent TB • Tuberculin skin test (TST) • Interferon release assays

  12. Symptomatic screen • Most commonly done • Screens vary – most validated include • Cough > 2/3 weeks • Fever (>2 weeks) • Night sweats (severe, > 2 weeks) • Unintentional weight loss (>10%) • Sensitivity high, specificity low7 7. Mosimaneotsile, Lancet 2003

  13. Chest X-rays • Less availability in low income settings • Difficult to interpret • Lower sensitivity than symptoms, ? Improved specificity • Not cost effective8,9 • Places where available tend to have less TB 8. Schneider, Arch Int med 1996, 9. Ho Int J STD AIDS 1999

  14. Sputum examination • Sputum smear • Cheap and readily available • Poor sensitivity • High specificity • Sputum culture • Expensive, less available • Improved sensitivity • Liquid culture may lead to increased NTM detection

  15. When & Where to Screen? • On diagnosis – VCT, PMTCT, HIV care • Every visit

  16. Screen all HIV infected individuals for TB Active TB Unknown No TB VCT/PMTCT

  17. Screen all HIV infected individuals for TB Active TB Unknown No TB ART/HIV Clinical setting

  18. TST • Over 100 years old, skin test • Cheap, limited facilities needed • False positives • Anergy in HIV positives

  19. Interferon - γ assays • In-vitro assays using the M.tb region of difference 1 (RD1) antigens • Higher specificity than TST • ? Better sensitivity although need to use a variety of Ag 10 • Limited experience in HIV+ high TB prevalence areas11 • Expensive and need lab facilities What is the gold standard? 10. Pai, Lancet Inf Dis 2004, 11. Chapman, AIDS 2002

  20. Do we need to diagnose latent TB in high prevalence countries? • We need to exclude active TB BUT • Can we assume exposure +/- infection and use the expensive RD1 assays in low prevalence, high income countries?

  21. TB Prevention • INH 5mg/kg daily • Duration 6-12 months ? Sufficient in high TB transmission areas • Other regimens equally effective but higher toxicities and more potential drug interactions • ? Value with ART H & RZ Placebo

  22. Summary Screen all HIV infected populations for TB Treat active TB High income, low TB prevalence Low income, high TB prevalence Test latent TB Exclude active TB Asymptomatic early HIV, PMTCT/VCT TB Preventive therapy

  23. Acknowledgements • ZAMBART Project Team • Peter Godfrey-Faussett & Nulda Beyers • LSHTM & UNZA

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