A six-month course of isoniazid preventive therapy (IPT) for tuberculosis greatly reduces the risk that people with HIV will progress from latent to active TB or die of the disease. TB is the leading cause of death among HIV-positive people in developing nations with the highest rates of HIV.

Researchers screened 7,361 HIV-positive Brazilians and found that 1,455, or 20 percent, were positive for TB infection but did not have any symptoms of the disease, qualifying them to begin taking the daily oral regimen of IPT for six months. To allow for a control comparison period, the study arranged so that every two months two of each of the 29 participating clinics would begin all their participants on therapy at once. The four-year study saw 838 deaths; 475 people developed active TB.

The investigators found that IPT lowered TB deaths and new cases of active TB disease by 31 percent; alone, new cases of active TB dropped by 27 percent.

Jonathan E. Golub, PhD, an associate professor at Johns Hopkins Medicine and one of the study’s co-authors, says IPT is “a relatively simple intervention to give, especially because it’s already recommended to be done in Brazil.”