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TB Notes Newsletter

(PDF - 1.7 MB)

No. 4, 2013


A High-Tech Approach to an Age-Old Problem

A new, cutting-edge diagnostic tool that helps detect TB in hours instead of days or weeks is being studied at 13 sites in Botswana, in hopes of improving TB detection time and getting more people treated faster.

TB remains the leading killer of people living with HIV (PLHIV). In 2012, as many as 63 percent of TB patients in Botswana were co-infected with HIV. Additionally, Botswana faces a growing threat from multidrug-resistant (MDR) TB, a disease that is much more difficult to diagnose and successfully treat.

Until recently, health providers routinely relied on smear microscopy, a diagnostic tool developed more than 100 years ago, to detect TB in the sputum of patients. But this method can miss many TB cases — especially among PLHIV — and does not detect drug resistance. Other diagnostic methods can detect drug resistance, but it can take many weeks or months to receive results.

It is hoped that a newly introduced diagnostic tool, called Xpert MTB/RIF, will help Botswana TB patients be treated as soon as possible through the rapid and accurate detection of TB disease and drug resistance. Thus, Xpert MTB/TIF may enable patients to be treated more quickly and, ultimately, save more lives.

Xpert MTB/RIF is a molecular test that uses a DNA probe in a sealed test kit to detect TB in sputum with greater sensitivity than traditional tests, while also detecting resistance to rifampicin, one of the most effective first-line TB drugs, much more quickly. The test can be performed simply and safely by minimally trained staff, with results in approximately 2 hours as compared to the days or weeks that it took before.

The U.S. government and the Botswana Ministry of Health have partnered to embark in an evaluation called XPRES (Xpert Package Rollout Evaluation Study) of the first 13 Xpert devices used in Botswana. The study’s objectives are to 1) compare the sensitivity of the new Xpert diagnostic tool versus the older smear microscopy–based diagnostic tool when providing TB screening for PLHIV, and 2) evaluate the impact of Xpert on mortality rates of patients newly enrolled in antiretroviral therapy (ART).

Nurse preparing a sample

The study began in August 2012 and, to date, more than 4,300 participants have been enrolled. Machines have been placed in 12 districts covering 22 HIV care and treatment clinics that serve approximately 50 percent of PLHIV accessing ART. Lessons learned from the initial sites have informed the recent national expansion of the machines to an additional six sites — and plans for 14 more — across Botswana.

Photo: clinic nurse preparing a sample for analysis using Gene Xpert at a point-of-care clinic, Botswana.

Developing a successful new testing procedure in Botswana should help contain the spread of TB, which, in addition to saving lives here, could have an important public health benefit elsewhere in Africa and in the rest of the world.

Reported by Doug Johnson, MPH
Communications Officer, CDC Botswan
Submitted by Alyssa Finlay, MD
CDC Botswana

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