Whilst much progress has been made with regards to suppressing the scourge of HIV & AIDS – especially by making antiretroviral therapy (ART) more readily available to people living with the disease - new challenges are being raised. Even though many resource-limited countries are rapidly expanding their HIV & AIDS treatment programmes, it is clear that HIV and TB co-infection is a major public health threat that puts at risk the success of the scale-up of ART. Resource-limited settings account for most of the world’s HIV & TB co-infection cases, with a staggering 79% of people known to be co-infected found in Africa alone. South Africa carries the highest absolute burden.

An estimated 1.3 million people died from TB in 2008. TB is the leading cause of death among people living with HIV. It is estimated that one in four deaths due to TB is related to HIV co-infection. When someone is infected with TB, the likelihood that they will become sick with the disease is greatly increased if they are also HIV-positive. Even though ART is an important way to reduce the incidence of TB in people living with HIV, HIV-positive people remain highly vulnerable to the disease. The emergence of drug resistant TB in countries with a high HIV prevalence poses an additional public health threat. HIV-positive people are also at a much greater risk of mortality from multi-drug resistant (MDR)-TB or extreme drug resistant (XDR)-TB, as it attacks their already weakened immune systems and, as its names suggest, does not respond to standard treatment regimens.

HIV & AIDS services in resource-limited settings generally lack provision for TB care, thus calling for urgent action to prevent, diagnose and treat TB in people living with HIV. This CAI brief explores in more detail the relationship between HIV and TB and its implications.

HIV and TB co-infection

TB is a highly contagious disease, caused by the bacteria Mycobacterium Tuberculosis. In its most common variant it attacks the lungs and spreads easily through the air, especially when an infected person comes in close contact with others. An estimated one third of the world’s population is infected with this latent bacterium, of which only 5-10% will actually become sick or infectious. If a person has both HIV and TB infection, the likelihood that they will develop active TB greatly increases. HIV is the most important factor contributing to the increase in the incidence of TB in Africa.

In South Africa, 80% of TB cases occur in people with HIV. However, TB is often not detected in HIV-positive people, making it difficult to determine the true number of deaths caused by TB. Furthermore, most cases of death by TB in HIV-positive patients are not caused by a drug-resistant strain of TB. This means that early detection and prompt treatment with ‘first line’ antibiotics could have saved their lives, and stemmed the transmission of TB, too. If started early enough, ART can also prevent TB in HIV-positive patients. The South African Government has thus revised its HIV & AIDS treatment guidelines to recommend earlier ART for patients with HIV & TB co-infection.

The role of the mining industry

Research into the prevalence of TB has shown that mining plays an important role as a contributor to TB in Africa; more so than previously realised. It had been assumed that increases in TB infection were largely driven by increases in HIV infection. However, even in areas with low HIV infection rates, TB has managed to flourish. This could be because miners live and work in close proximity to one another, in crowded hostels and dust-choked mine shafts. Since many miners are migrants, in their trips home, they are vulnerable to interrupting their courses of antibiotics, either because they fail to take adequate provisions, or because they deliberately stop taking their medication to assuage the stigma of being sick. This increases their chances of developing a drug resistant strain of TB, with which they can then infect their families and communities, as well as compromising their own recovery, inflaming the severity of the problem.

Multi-drug resistant (MDR)-TB and Extreme drug resistant (XDR)-TB

MDR-TB is a strain of TB bacteria that is resistant to two or more ‘first line’ antibiotic drugs. Such drug resistance can arise in and spread from TB patients not taking their medicine as prescribed. When a person has MDR-TB, ‘second line’ antibiotic drugs are administered. ‘Second line’ drugs prolong treatment and are often more expensive than ‘first line’ drugs. They also produce more severe side-effects. When a strain of TB bacteria is resistant to three or more ‘second line’ antibiotics, it is referred to as XDR-TB. It is virtually impossible to treat XDR-TB and most people with this strain will die before it is even known that they have XDR-TB.

The emergence of drug-resistant strains of TB poses a severe threat to the control of the disease, and calls urgently for strengthening the control of TB infection as well as the management of TB treatment, especially in Africa.

The 3I’s Strategy - Intensified Case Finding, Isoniazid Preventive Therapy and TB Infection Control for people living with HIV

The World Health Organisation (WHO) established the 3I’s strategy in 2004 in an effort to reduce the burden of TB among HIV-positive people. This strategy has since been incorporated into the Global Plan to Stop TB, 2006 - 2015. It has annual collaborative targets linked to Millennium Development Goal 6, Target 8: Halt and begin to reverse the incidence of TB by 2015. The core of this strategy is DOTS – directly observed treatment, short course. The six-month treatment costs very little and cures 95% of TB cases.

In addition, Intensified Case Finding (ICF) has the benefit of earlier detection of TB. Earlier detection means earlier start to treatment. By suppressing the disease early on, the ICF strategy also helps Infection Control (IC). Where TB infection is not controlled, the possibility of drug resistant strains of TB increases, placing not only the HIV-positive individual at greater risk, but also the wider community. Another means to controlling the spread of TB is Isoniazid Prevention Therapy (IPT), which can prevent latent TB infection – where the body has been able to successfully fight the bacteria and stop them from causing illness – from developing into active TB – where the immune system is unable to stop the bacteria from causing illness. IPT can reduce the risk of TB in people living with HIV by 33-62%.

The WHO recommends that the 3I’s become a central part of HIV care and treatment, as they are critical for the continued success of ART scale-up. Furthermore, the WHO recommends that all people living with HIV or at risk of contracting HIV, especially in areas of high co-infection prevalence, be screened for TB. IC is a key part of this screening process.

Conclusion

There is no reason why a curable disease such as TB should become a death sentence for HIV-positive people. With the scale-up of ART, many HIV-positive people are able to lead relatively normal and healthy lives. The 3I’s are key to public health strategies that aim to reduce the impact of TB on HIV-positive people. More attempts need to be made to improve collaboration between TB and HIV programmes. One proposal is that everyone diagnosed with TB should be tested for HIV and vice versa. Another is earlier diagnosis and earlier initiation of treatment. However, such collaboration is not easily achieved, especially in the wake of the economic crisis and its subsequent funding downfall. Nevertheless, it is imperative that governments and donors do not lose focus at this important stage of the pandemic of co-infection.

NOTES:

(1) Amy Vice is an External Consultant for Consultancy Africa Intelligence’s HIV & AIDS Unit ( This e-mail address is being protected from spambots. You need JavaScript enabled to view it ).