THE CHANGING PATTERN OF CLINICAL TUBERCULOSIS IN THE AIDS ERA - THE ROLE FOR PREVENTIVE THERAPY

The interaction between tuberculosis and HIV infection has dramaticall y changed the clinical and epidemiological profile of tuberculosis wor ld-wide. While HIV infection alters the pathogenesis of tuberculosis t hrough changes in cell-mediated immunity, there is now growing evidenc e that tuberculosis may alter the course of HIV infection by stimulati on of viral replication. While pulmonary tuberculosis remains the most common presentation, even in areas of high HIV prevalence, the propor tion of smear-negative and extrapulmonary disease is increased in HIV infection. Radiologically, middle and lower-zone disease is more commo n and cavitation less frequent. Infectiousness of HIV-associated tuber culosis is equal or reduced as compared to tuberculosis in HIV-negativ e patients. Drug-sensitive HIV-associated tuberculosis generally respo nds well to standard antituberculous regimens but there is a higher in cidence of adverse drug reactions. Multi-drug resistant tuberculosis h as been reported in isolated groups of HIV-infected patients but as ye t does not appear to be a widespread problem. From the limited studies published to date, isoniazid preventive therapy in HIV-infected patie nts appears to be efficacious, at least in those who are positive for the tuberculin skin test. Despite this there are important practical p roblems to be addressed before it can be recommended as a public healt h intervention, even for selected groups of HIV-infected persons.