Anti-retroviral drugs reduce tuberculosis infection in people with HIV
People in low and middle income countries who are HIV positive and are taking anti-HIV drugs (antiretroviral therapy) are significantly less likely to develop tuberculosis relative to those who are not taking antiretroviral therapy, irrespective of the CD4 count (a biomarker of immunodeficiency) at which they start taking antiretroviral therapy, according to a study by international researchers in this week’s PLoS Medicine. This protective effect was also seen in adults with CD4 counts above 350 cells/mm3 (the World Health Organization currently recommends antiretroviral therapy in adults with CD4 counts below 350 cells/mm3).
People who are HIV positive are extremely susceptible to tuberculosis because the HIV virus destroys the immune system cells that are necessary to combat tuberculosis infection. In 2010, there were 1.1 million new cases of tuberculosis among 34 million people living with HIV and 350,000 people died of HIV-associated tuberculosis, making tuberculosis the leading cause of death among HIV-positive people.
In an analysis led by the World Health Organization, the authors combined 11 relevant studies from Sub-Saharan Africa, South America, the Caribbean, and Asia and found that study participants taking antiretroviral therapy had a 65% reduction in their risk of developing tuberculosis relative to study participants who were not receiving antiretroviral therapy, irrespective of the CD4 count at which they started taking antiretroviral therapy.
Importantly, the authors found that taking antiretroviral therapy was associated with a 57% reduction in tuberculosis risk among adults with CD4 counts greater than 350 cells/mm3; currently the World Health Organization recommends antiretroviral therapy below this threshold in adults with HIV.