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The TB Crisis in HIV/AIDS Patients

Posted on: Sunday, 14 August 2005, 03:01 CDT

New diagnosis for better outcomes

Ready access to reliable, timely, and affordable diagnostic tests and treatments for TB would have a dramatic impact on outcomes for HIV/AIDS patients worldwide. TB kills more HIV/AIDS patients in the developing world than any other infectious complication.

The problem is catastrophic in sub-Saharan Africa, where the two diseases make a deadly combination. Here, TB is the leading killer of HIV-positive people. Key factors are

* TB is harder to diagnose and progresses faster in HIV-positive people; and

* TB in HIV-positive people is almost certain to be fatal if undiagnosed or left untreated.

TB treatment can, nonetheless, be successful in HlV-positive patients. Treatment with anti-TB drugs prolongs the life of people living with HIV by at least two years, according to the World Health Organization (WHO). Effective screening and diagnostic capabilities - requiring planning and significant investment - are essential prerequisites for effective TB-treatment programs. It is important that people who have the disease be identified at the earliest possible stage so that they can receive treatment, contacts can be traced, and measures can be taken to minimize the risk to others.

Diagnosis before treatment

"Diagnosis before treatment" is a basic principle of good medical practice and is especially important in TB management. A major challenge in diagnosing TB in HIV/AIDS patients is the fact that their sputa often contain few or no mycobacteria because they are less likely to have cavitary lung disease and more likely to have extrapulmonary disease than other TB patients. As a result, the standard diagnostic procedure of identifying mycobacteria in stained sputa samples is highly insensitive. Classical culture methods are more sensitive but notoriously slow, taking 21 to 42 days.

A promising new agreement intended to help tackle this issue was recently entered into by the Foundation for Innovative New Diagnostics (FIND), a nonprofit organization established with funds from the Bill and Melinda Gates Foundation, and BD. Improved liquid- media-based culture methods are now available, such as our mycobacteria growth indicator tube (MGIT) system, which can often confirm the diagnosis of TB in eight to 14 days and provide key information on drug susceptibilities after only five more days.

Table 1. TB and HIV: the evil twins

While the MGIT is available in industrialized countries, few instruments have yet reached the developing world. FIND aims to demonstrate the effectiveness of more rapid and accurate TB diagnosis using equipment, reagents, training, and support we provide on terms designed to enable sustainable use.

WHO, FIND, and BD goals

The joint goals of the three groups - WHO, FIND, and BD - are to improve diagnosis of pulmonary TB in HIV-positive patients in developing countries, especially those with high prevalence of multidrug-resistant TB, and to promote diagnostic technology to national TB and AIDS programs.

Improving diagnostic capabilities and infrastructure remains the key to achieving better outcomes for patients. Dr. Mario Raviglione, director of the WHO'S Stop TB department, says, "This new agreement provides a blueprint for modern TB technology to be made more widely available globally, which will help reduce TB deaths and decrease transmission rates in high-risk areas."

"Diagnosis before treatment" is a basic principle of good medical practice and is especially important in TB management.

HIV/AIDS is fueling the TB epidemic in sub-Saharan Africa, where up to 70% of TB patients are co-infected with HIV in some countries - a "dual epidemic."

By David T. Durack, MD, DPhil

David T. Durack, MD, DPhil, is vice president of corporate medical affairs for medical technology company BD, with offices at Research Triangle Park, NC, and at Franklin Lakes, NJ. BD is the manufacturer of the trademarked BD MGIT system.

Copyright Nelson Publishing Aug 2005

Source: Medical Laboratory Observer; MLO

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