TB + HIV: Do You Know The Facts - 2005

By Kate Greenaway.

Most of us know the basics about TB. For instance, we know that it is a bacterial disease which spreads, like the common cold, through the air. We know that the most common form of TB is found in the lungs (called pulmonary TB) but that it can infect any part of the body (the brain, the bones, etc.). We've been taught that people who are sick with TB in their lungs are infectious - the other forms of TB are not as easily spread even though they can be life-threatening to the patient. And we know that it's a global threat: about a third of the world's population is currently carrying TB; in fact, it's estimated that one new person in the world is infected with TB every second.  

But obviously, not all these people have active TB. In fact, most people carrying the TB germs (or "bacilli") will never actually fall sick with TB, because their immune systems are able to keep it in check by "walling off" the bacilli with a thick waxy coat. These people have "latent" or "dormant" TB, which may never develop into illness or become contagious. It's only "active" TB which causes illness and is contagious.  

In southern Africa, however, the high prevalence of HIV has distorted the normal pattern of TB. An immune system weakened by HIV isn't strong enough to wall off the TB bacilli before they start to cause illness. In fact, HIV and TB form a lethal combination, each speeding the others progress: having HIV increases the probability of getting sick from TB exposure, and at the same time, TB exposure increases the probability that the HIV infection will progress. Thus TB and HIV, when found together, are flourishing in spite of our efforts to contain them.  

Having both TB and HIV is called "co-infection" and can be harder to recognize than TB from the pre-HIV days. When CD4 counts are still high, "normal" TB of the lungs is most often seen. TB is, in fact, very likely to occur in the early days of HIV infection. As the CD4 count drops, however, TB becomes harder to diagnose and is more likely to affect organs outside of the lungs. This makes diagnosis and treatment more complicated and expensive. Fever, fatigue and weight loss are reliably experienced and often interpreted (by the patient) as "AIDS" rather than TB, thus they may decline to seek the treatment which could restore their health.  

The good news is that TB is treatable with modern medicines and completely curable even when HIV is present. The recommended international approach to TB control is called DOTS (Directly Observed Treatment, Short-course). This strategy involves the provision of a regular and uninterrupted supply of high-quality anti-TB drugs, six to eight months of supervised treatment, including direct observation of the patient taking his/her medicine during at least the first two months. Mortality rates among co-infected patients are unnaturally high, because of increased susceptibility to pneumonia, malaria and other infections, especially during the time that they're sick with TB. The use of Cotrimoxazole is often recommended as a prophylactic medication for people with HIV (with or without TB), to decrease the risk or severity of these the infections. While Cotrim doesn't cure TB, studies have shown that adding it to the TB treatment package gives patients extra protection against these other illness while their TB is being treated, thus reducing their risk of death.  

Another challenge is the multi-drug-resistant strains of the TB bacilli that have begun to emerge around the world (called MDR-TB). The leading cause of MDR-TB is inconsistent or partial treatment. Failing to take medication as prescribed provides the TB bacilli the opportunity to alter itself so that the drugs no longer kill it. When this MDR-TB spreads to a new person, s/he will also have a drug-resistant form of the disease.

Incomplete TB treatment is worse than no treatment at all. When a drug resistant strain of TB develops it becomes much more difficult to treat the patient successfully and to control the spread of the disease. The treatment for drug resistant TB is much longer, requires more expensive drugs, and is more dangerous for the person being treated.  

World TB Day, March 24, presents a great opportunity to share this crucial information with family and colleagues. The estimated incidence per capita in sub-Saharan Africa is the highest in the world, and TB has recently become the leading cause of death related to AIDS in Southern Africa. None of us should be in the dark. Knowledge is power. Do your part on World TB Day and pass this along!