HIV-tuberculosis coinfection is a major global health emergency, with TB being the leading cause of death among people living with HIV worldwide. The interaction is bidirectional: HIV infection causes profound CD4 T-cell depletion and macrophage dysfunction, dramatically increasing the risk of new TB infection, reactivation of latent TB, and progression to disseminated disease (lifetime TB risk in HIV-positive individuals is 50-60% versus 5-10% in HIV-negative); conversely, active TB increases viral replication, accelerates immunodeficiency, and worsens HIV outcomes. Coinfection rates are highest in sub-Saharan Africa and parts of Asia.
Clinical presentation in HIV-positive patients varies with CD4 count: with relatively preserved immunity (CD4 > 350), TB resembles classic presentation with predominantly pulmonary involvement and cavitation; with advanced immunosuppression (CD4 < 200), presentations are atypical with extrapulmonary disease (50-70%), disseminated TB, miliary TB, smear-negative pulmonary disease, atypical chest X-ray patterns (lower lobe, hilar adenopathy, pleural effusion without cavitation), and rapid progression. Diagnosis is challenging due to lower bacillary load (lower yield of smears and cultures), atypical imaging, and overlapping symptoms with other opportunistic infections.
Management requires coordinated anti-TB and antiretroviral therapy (ART): standard 6-month TB treatment is generally adequate, though longer for CNS or osteoarticular TB; ART should be initiated within 2-8 weeks of TB treatment depending on CD4 count (sooner if CD4 < 50) to reduce mortality despite increased risk of immune reconstitution inflammatory syndrome (IRIS). Drug interactions are critical: rifampicin induces cytochrome P450, reducing levels of protease inhibitors (use rifabutin instead) and integrase inhibitors (dolutegravir requires double dosing). IRIS-TB occurs in 10-30% during ART initiation, presenting with worsening or new TB manifestations 2-12 weeks into therapy and may require corticosteroids. Latent TB infection screening with IGRA and isoniazid preventive therapy (6-9 months) is recommended for all HIV-positive individuals.