Effective, Affordable Tests Required for TB Diagnosis

Most people in the world who have TB or live in TB-risk areas do not have good access to rapid and accurate testing, states the report. Improved tests are needed to bolster international TB control efforts.

One-third of the world's population is infected with latent TB and at risk of developing the active disease. Human immunodeficiency virus (HIV) is fuelling TB epidemics in many countries, and multi-drug resistance is a growing threat. Every year 1.7 million people die from TB, many because the infection goes undiagnosed, or is diagnosed too late to be cured. "The TB and HIV threat continue to grow in many parts of the world, and governments need high-quality diagnostics to help manage these epidemics,” said Dr. Robert Ridley, director of TDR. "We need simple tests to accurately screen for, and identify, active tuberculosis. New tests also are needed to monitor treatment response, to identify bacterial drug resistance, and to detect latent infection in people at greatest risk for progression to active TB.”

In low- and middle-income countries where three-quarters of the TB tests and screenings are carried out, around U.S.$326 million annually is spent on TB diagnostics--and an even larger potential market exists for more effective and affordable tools. Between 70-90% of the potential available market for new TB diagnostics is concentrated in 22 countries with the highest burden of TB. High-tech molecular and rapid culture diagnostics available in developed countries are too complex and costly for many settings where TB is most prevalent. The traditional sputum smear, x-ray, and culture tests may not accurately identify active TB, particularly in HIV-positive patients. Such diagnostics may fail to distinguish between latent and active TB, and between drug-sensitive and drug-resistant forms of the disease.

Despite increased global funding for TB control, and the emergence of public-private partnerships to support product development, commercial interest in TB diagnostics has been limited by a dearth of information on the size and character of the TB diagnostics market, especially in the developing world. The majority of recently developed tests serve sophisticated laboratories in industrialized countries, where less than 5% of global tuberculosis cases are found. A test that detects latent infection and predicts progression to active disease would be the most useful, with a potential available market of some 204 million patient evaluations a year. The report concludes: "Such a test, if widely implemented and accompanied by successful treatment, could revolutionize TB control.”



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