Tuberculosis & hiv coexistence

Tuberculosis & hiv coexistence

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  Tuberculosis & HIVCoexistence Dr. Kanwal Deep Singh Lyall M. D. Microbiology
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  TB/HIV • TB andHIV are closely interlinked. • TB is leading cause of HIV-related morbidity & mortality. • HIV is most important factor fuelling TB epidemic • HIV is most powerful factor known to ↑ risk of TB. • TB can occur at any point in the course of progression of HIV infection • A person infected with HIV has a 10 times ↑ risk of developing TB.
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  • HIV ↑susceptibility to infection with M. Tb • HIV ↑ risk of progression of M. Tb infection to Tb disease. • ↑ rate of progression of recent or latent M. Tb infection to disease. HIV status Lifetime risk of developing TB negative 5–10% positive 50%
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  Facts • TB -leading cause of death among people living with HIV in Africa & a major cause of death elsewhere. • ≈ 1.4 million HIV positive TB patients globally in 2008 • 500,000 people died of HIV-associated TB in 2008. • At least 1/3 of the 33.2 million people living with HIV worldwide are infected with TB, • Are 20-30 times more likely to develop TB than those without HIV • 1 in 4 people with HIV die due to TB. • People living with HIV are facing emerging threats of drug- resistant TB
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  Co-pathogenicity of TB& HIV Disease • M. Tb enter lungs- taken up by alveolar macrophages- present Ags to Ag-specific CD4+ T cells • T cells release cytokines that activate macrophages & enhance their ability to contain M.tb infection. • Activated macrophages also release pro-inflammatory cytokines, such as TNF & IL-1 • Mycobacteria & their products also enhance viral replication • They induce nuclear factor kappa-B, the cellular factor that binds to promoter regions of HIV
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  • In Tbmajor effecter cell in cell mediated immunity are CD4+ T-cells • In HIV the target cells are the same CD4+T-cells • So without protection the Tb infection disseminates
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  • Immune activationfrom TB enhances both systemic and local HIV replication. • The plasma HIV RNA level rises substantially before Tb is diagnosed • TB treatment alone leads to reductions in the viral load in these dually infected patients. • TB & HIV also interact in lungs, site of 1º infection with M. Tb • In HIV-infected patients with Tb, researchers found that viral load was higher in BAL from affected versus unaffected lung
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  Consequences of coexistence •Over diagnosis of sputum smear-negative PTB • Under diagnosis of sputum smear-positive PTB • Inadequate supervision of anti-TB chemotherapy • Low cure rates • High morbidity during treatment • High mortality rates during treatment • High default rates because of adverse drug reactions • High rates of TB recurrence • ↑ transmission of drug-resistant strains among HIV-infected
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  HIV /TB inchildren • Several HIV-related diseases, including TB, may present in a similar way • The interpretation of tuberculin skin testing is less reliable • In early HIV infection-immunity good, signs of TB are similar to those without HIV • In late HIV infection -immunity declines-dissemination of TB • Tubercular meningitis, miliary TB, widespread tuberculous LAP
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  Clinical Features SuggestiveOf HIV Co-infection In TB Patients Past history •Sexually transmitted infection history •Herpes zoster (shingles) •Recent or recurrent pneumonia •Severe bacterial infections (sinusitis, bacteraemia, pyomyositis) •Recent treated TB Symptoms •Weight loss (> 10 kg or > 20% of original weight) •Diarrhoea (> 1 month) •Retrosternal pain on swallowing(suggests oesophageal candidiasis) •Burning sensation of feet(peripheral sensory neuropathy) Signs •Scar of herpes zoster •Pruritic (itchy) papular skin rash •Kaposi sarcoma •Symmetrical generalized lymphadenopathy •Oral candidiasis •Angular cheilitis •Oral hairy leukoplakia •Necrotizing gingivitis •Giant aphthous ulceration •Persistent painful genital ulceration
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  Radiological findings • Theclassical pattern is more common in HIV-negative patients, & atypical pattern in HIV-positive patients. CLASSICAL PATTERN ATYPICAL PATTERN upper lobe infiltrates , bilateral infiltrates interstitial infiltrates (especially lower zones) Cavitation intrathoracic lymphadenopathy pulmonary fibrosis and shrinkage no cavitation, no abnormalities Early HIV Late HIV
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  • PTB iscommonest form of TB • The commonest forms extrapulmonary TB are: • Pleural effusion, lymphadenopathy, pericardial disease, miliary disease, meningitis, disseminated TB (with mycobacteraemia) Features of PTB Stage of HIV infection Early late Clinical picture Often resembles post-primary PTB Often resembles primary PTB Sputum smear result Often positive Often negative CXR appearance Often cavities Often infiltrates with no cavities
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  Tuberculin skin (Mantoux)test • Tuberculin skin reactivity - dependant on cytokine mediated cellular immunity • An induration of ≥5 mm , in response to 1 TU of PPD tuberculin = a positive response, in HIV-infected individuals • In TB high prevalence countries like India, tuberculin skin testing has no value in TB diagnosis, as a positive test indicates prior infection only & false negativity
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  Treatment of TB& HIV co-infection • Till date no cure is available for HIV/AIDS • Anti retroviral drugs used to treat HIV/AIDS effectively slow down action of virus & prolong life of patients • Treatment for TB is same for HIV infected as for non-HIV infected TB patients. • Same criteria determine treatment category for TB patients irrespective of HIV status.
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  • Current guidelinesrecommend that irrespective of HIV status, TB requires a minimum of 6 months of treatment with 4 drugs (including rifampin) in intensive phase & 2 drugs in continuation phase • Treatment consists of INH, RIF, EMB & PYZ x 2 months • f/b INH and RIF for 4 months, given either daily or intermittently.
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  Anti-TB drug resistance •MDR-TB is marginally higher (3-4%) in HIV positive patients with newly diagnosed TB • Rifampicin mono- resistance is more common in HIV infected patients may be due to malabsorption of anti-TB drugs • Outcome of MDR-TB in HIV is poor • Strains of M. tuberculosis labelled as (XDR) TB have emerged and spread rapidly through HIV-infected populations leading to high mortality
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  Thank You