RESEARCH ON TB

TB & HIV


In 2011 1.1 million (13%) of the estimated 8.7 million people who worldwide developed active TB disease were HIV positive.11 People living with HIV are up to 37 times more likely to develop TB disease than people who are HIV negative.12 But although HIV increases the likelihood of progression from latent TB infection to active TB disease, it is not known whether HIV infection increases the risk of become infected if someone is exposed to TB bacteria.13 HIV and TB co-infection means that a person is infected with HIV and also has TB bacteria in their body

Globally in 2011, there were an estimated 1.7 million deaths from HIV, and of these people an estimated 430,000 (25%) also had TB.

How can TB be prevented?

There are a number of steps that can be taken to prevent the spread of TB, and these include:

  • The use of the BCG vaccine
  • Drug treatment to prevent people with latent TB from developing TB disease.
  • Infection control measures to prevent health care workers and other people in contact with people with active TB disease, from becoming infected; and drug treatment for people with active TB disease will also prevent transmission of TB bacteria to other people, as drug treatment makes a person less infectious
TB and HIV - why is it important?

TB and HIV co-infection is when people have both HIV infection, and also either latent or active TB disease.
In 2011 430,000 people are estimated to have died of TB and HIV co-infection, in addition to the 990,000 people who died from TB alone.
Those people who have HIV infection as well as TB when they die, are internationally reported as having died of HIV infection.

In total an estimated 1.7 million people died of HIV infection in 2011.3 So this means that the deaths from TB and from HIV are:

  • Deaths from HIV and TB co-infection: 430 000
  • Deaths from TB alone: 990 000
  • Deaths from HIV alone: 1 270 000

So with an estimated 1.42 million people having active TB when they died, of these 30% also had HIV infection. In the same year there were an estimated 8.7 million new cases of active TB worldwide, of which 1.1 (13%) million are estimated to have been among people living with HIV. Seventy nine per cent of the HIV positive TB cases were in the African region.

The World Health Organisation (WHO) reported that in 2010, 350 000 people died who had active TB and HIV infection, meaning an increase between 2010 and 2011. Yet despite this in November 2012 UNAIDS reported that there had been a 13% reduction in TB associated HIV deaths in the last two years.

“We cannot win the battle against AIDS if we do not also fight TB. TB is too often a death sentence for people with AIDS. It does not have to be this way. We have known how to cure TB for more than 50 years. What we have lacked is the will and the resources to quickly diagnose people with TB and get them the treatment they need.”

Nelson Mandela July 15, 2004

The undercurrent of the global HIV epidemic is driving the resurgence of TB, and is already having an impact on the global TB epidemic, especially in sub-Saharan Africa.7 Indeed HIV and TB co-infection is a major public health threat that directly jeopardizes the success of the antiretroviral scale up that has resulted in millions of people living with HIV in developing countries now receiving HIV antiretroviral treatment.

The natural history of TB in people with HIVDemands for TB funding

Demands for TB funding at an HIV conference © GHE

When people have a damaged immune system, such as people with HIV who are not receiving antiretroviral treatment, the natural history of TB is altered. Instead of there being a long latency phase between infection and development of disease, people with HIV can become ill with active TB disease within weeks to months, rather than the normal years to decades.

The risk of progressing from latent to active TB is estimated to be between 12 and 20 times greater in people living with HIV than among those without HIV infection.9 This also means that they may become infectious and pass TB on to someone else, more quickly than would otherwise happen. Overall it is considered that the lifetime risk for HIV negative people of progressing from latent to active TB is about 5-10%, whereas for HIV positive people this same figure is the annual risk.

Many people living with HIV are now taking antiretroviral treatment for their HIV infection. This helps their immune system, but the risk of developing active TB is still higher than in people without HIV infection.11 Also, there are reports from some African countries that people are starting to become infected with drug resistant HIV. This makes it much more difficult to provide them with effective antiretroviral therapy, and this in turn could result in millions more, of the estimated 40 million people thought to be living with HIV worldwide, developing active TB in the next few years.

TB and HIV co-infection

If a person has HIV and TB co-infection it means that they have both HIV infection and either latent TB or active TB disease. When someone has both HIV and TB, each disease speeds up the progress of the other. In addition to HIV infection speeding up the progression from latent to active TB, TB bacteria also accelerate the progress of HIV infection.

HIV infection and infection with TB bacteria are though completely different infections. If you have HIV infection you will not get infected with TB bacteria unless you are in contact with someone who also is infected with TB bacteria. Although if you live in a country with a high prevalence of TB this may have happened without you realizing it.

Similarly if you have TB you will not get infected with HIV unless you carry out an activity with someone who already has HIV infection, which results in you getting the virus HIV from them.

TB also occurs earlier in the course of HIV infection than many other opportunistic infections. The risk of death in co-infected individuals is also twice that of HIV infected individuals without TB, even when CD4 cell count and antiretroviral therapy are taken into account.

It is estimated that one third of the 40 million people living with HIV/AIDS worldwide are co-infected with TB.

Winstone Zulu
Winstone Zulu 1964-2011
Winstone Zulu

One of the first people to speak out openly about the problems of TB and HIV co-infection was the Zambian Winstone Zulu. Winstone was a prominent global advocate on TB and HIV.

Winstone was the first person in Zambia to speak openly about being HIV positive. Also, although he himself survived TB he watched four of his brothers die from TB due to lack of access to anti TB drugs. He was moved to turn his personal loss into ceaseless advocacy for worldwide awareness for the fight against TB and TB-HIV co-infection.

“There have been so few TB survivors who have stepped forward to share their stories. We need more advocates like Winstone to tell the world about TB and the effect it has on so many millions of people.”
-Nelson Mandela

Symptoms of TB in people with HIV

HIV positive people with pulmonary TB may have the classic symptoms of TB, but many people with both TB and HIV infection have few symptoms of TB or even less specific ones. In addition, up to a fifth of people with both pulmonary TB and HIV have normal chest X-rays. HIV positive people with TB may indeed frequently have so called "sub clinical" TB, which often is not recognized as TB and subsequently there are delays in both TB diagnosis and TB treatment.

HIV infected people are also more likely than people who are not infected with HIV to have extra pulmonary TB. Forty to eighty percent of HIV infected people with TB have extra pulmonary disease, compared with 10-20% of people without HIV.

Diagnosing TB and HIV in TB and HIV co-infection

Because of the limitations of current TB tests, it is even more difficult to diagnose TB in HIV positive individuals, than to diagnose TB in people without HIV infection. Many people with HIV will have a false negative result from a TB sputum smear test. This can result in a large number of cases of active TB disease going undiagnosed.

The results of a survey in an African community with high HIV prevalence and increasing TB notification rates, showed that 63% of adult cases with pulmonary TB remained undiagnosed in an efficient directly observed treatment short course (DOTS) program. The World Health Organisation recommends DOTS as an essential part of global TB control programs.

Treating TB and HIV co-infection

Initiating treatment for either HIV or TB

The decision to initiate treatment for either HIV or TB when there is co-infection, should take into account a number of factors including:

-Has the person got symptoms of, and is ill with either TB, or some other HIV related opportunistic infection?

-Is the person already having treatment for either TB or HIV infection?

-What drugs are available for the treatment of HIV infection, and indeed TB, if the person is not already receiving treatment?

-If there is a need for both HIV and TB treatment, are there experienced health care workers and/or guidelines available to provide the necessary expertise on this?

Providing HIV antiretroviral therapy and anti TB drug treatment together

The provision of HIV antiretroviral therapy and anti TB drug treatment at the same time involves a number of potential difficulties including:

  • Cumulative drug toxicities
  • Drug - drug interactions
  • A high pill burden
  • The Immune Reconstitution Inflammatory Syndrome (IRIS)