LEDs speed up effective diagnosis of tuberculosis

July 13, 2011 A novel technique known as LED-FM can diagnose tuberculosis more quickly and efficiently than current methods.
Researchers led by Luis E. Cuevas and Mohammed Yassin from the Liverpool School of Tropical Medicine have found that LEDs can be used to diagnose tuberculosis (TB).

The findings have important implications for the ways in which diagnosis for the endemic infectious disease, TB, can be done in poor countries. They suggest that a faster laboratory test can be used while maintaining the same level of accuracy for diagnosis as the currently used method. Also, testing using the alternative technique, known as LED Fluorescence Microscopy (LED-FM), is less labour-intensive and more convenient for patients.

 



A roentgenogram showing an infection of tuberculosis

 

In the study, the researchers examined nearly 2,400 patients from Ethiopia Nepal, Nigeria and Yemen who had had a cough for more than two weeks (a characteristic symptom of tuberculosis). The researchers used a variant form of smear microscopy (LED-FM) and identified more people with TB than the standard smear microscopy test (in which technicians use a stain called Ziehl Neelsen from a patient's sputum). The LED-FM technique was also faster than the standard test. 

According to the scientists, a further advantage of LED-FM could lead to more people without TB being needlessly treated, as it picks up more false positives.  In other words, it detects people who don't have TB but who are incorrectly classified as test-positive for the disease.

The authors conclude, "This study has shown that LED-FM can play a key role in reaching the World Health Organisation targets for TB detection, reducing laboratory workloads, and ensuring poor patients' access to TB diagnosis and prompt treatment."

The study was jointly coordinated with Andrew Ramsay at WHO-TDR Special Programme for Research and Training in Tropical Diseases.

The research was funded by the Bill & Melinda Gates Foundation and the United States Agency for International Development through grants awarded to the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases. The LUMIN and the QBC Paralens Fluorescence Microscopy Systems were provided free of charge by LW Scientific, which also paid the costs of shipping the systems to study sites.

Further details of this work are published in the paper, “ LED Fluorescence Microscopy for the Diagnosis of Pulmonary Tuberculosis: A Multi-Country Cross-Sectional Evaluation” by L.E. Cuevas et al, PLoS Med, 8(7): e1001057 (2011). doi:10.1371/journal.pmed.1001057

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