A new United Nations World Health Organization (WHO) publication issued shortly before the March 24 observance of World Tuberculosis Day, underscores the devastating impact that the spread of HIV (human immunodeficiency virus) has had on TB death rates in developing countries. It outlines the amplified risks of dying from TB for AIDS patients and for TB carriers who are also infected with HIV. UN Special Envoy to Stop TB, former Portuguese President Jorge Sampaio, addressed TB concerns in New York on Tuesday. He noted that of the estimated one-point-five million TB patients dying annually, 200-thousand also have HIV. Dr. Phillip Nieburg is a non-resident expert on infectious diseases at Washington’s Center for Strategic and International Studies (CSIS). He describes the relationship between the two ailments and explains how the spread of HIV complicates TB rates of survival.
“The connection works in several ways. For TB, HIV weakens the immune system, so people who have TB infections are more likely to have severe disease. That is, people infected with TB, most of whom would never gotten sick during their lifetime (the infection would healed itself), for those people who have HIV, they have a much more likely chance of having active disease. And if they develop active disease, there’s a much greater chance of having a severe outcome,” he said.
Although HIV weakens the immune system, Dr. Nieburg says the process can also work the opposite way: TB can disturb the immune system so that weakened individuals may be unlikely to fight off contracting HIV/AIDS.
“Things that stimulate the immune system actually cause HIV replication or multiplication to occur faster, so there’s a positive feedback system. People who are infected with tuberculosis have a faster progression of their HIV disease to AIDS and a faster progression of AIDS to a more serious version of it,” Nieburg explained.
As a result of the multiple ways co-infection can strike, Nieburg points out that tracking the progression of the ailments can be a tricky challenge for medical authorities in developing countries.
“Things are changing. A huge proportion of people in Africa have what’s called latent tuberculosis. That is, they’ve been infected some time early in their life, but they don’t have active disease. It’s quiescent, and for that group of people, when they get HIV, they have a large chance of having their HIV become activated. At this point, there are more TB-infected people than HIV-infected people. It’s just that the two populations are beginning to overlap more and more as HIV continues to spread. And then on a population level, as HIV spreads and more of those HIV-infected people develop TB, then more new people, who are not infected with either one, will be exposed to tuberculosis,” he says.
Nieburg, who is also an adjunct professor at the University of Virginia’s Center for Biomedical Ethics, points out that developing an integrated strategy for treating this lethal combined form of the infection is key to keeping the pandemic in check, particularly in Africa, where it is resurging.
“In general, over the last 30 years, TB rates have been falling all over the world. The global TB control program has been doing a great job. And before HIV came along, there was hope actually of eliminating active tuberculosis within our lifetime. The countries that are heavily impacted by HIV have now seen a reverse because so many TB patients are now developing active disease. So the more HIV-infected people there are in a country, the more chance there is that the TB rates will also be rising,” he noted