Epidemiology of tuberculosis and HIV: recent advances in understanding and responses

Although tuberculosis (TB) continues to cause enormous suffering and overwhelm health care systems in areas with high HIV prevalence, there have been a number of recent significant advances in knowledge regarding the epidemiology, management, and control of HIV-related TB. TB remains the most common serious opportunistic infection in people with HIV infection and the leading cause of death. However, there is some reason for optimism. First, two trials addressing when to start antiretroviral therapy (ART) in HIV-infected adults with newly diagnosed TB have shown that earlier initiation of ART reduces mortality significantly. Second, there is trial evidence of efficacy in giving long-term isoniazid preventive treatment (IPT) to HIV-infected adults in high HIV-prevalence settings where TB reinfection is frequent (much like cotrimoxazole). Third, the search for an inexpensive, rapid, sensitive, and specific TB diagnostic that is able to replace smear and delayed mycobacterial culture has yielded promising results. Responding to massive TB epidemics in high HIV-prevalence settings, the World Health Organization has supplemented its directly observed treatment short-course strategy with one called the 3I's to actively screen and diagnose TB cases (intensified case finding), prevent new cases of TB with IPT, and prevent transmission of TB in congregate settings such as hospitals and clinics (infection control). Combating TB in high HIV-prevalence settings requires rapid and massive implementation of the 3I's with initiation of antiretrovirals and more effective efforts to prevent new HIV infections.