New TB test to speed up diagnosis

A quick and accurate new blood test for diagnosing TB is being developed by scientists at St George’s, University of London.

Early results show the method of detecting TB by identifying a combination of telltale proteins — or biomarkers — in blood samples is up to 94% accurate, compared with the 40% to 60% accuracy of analysing sputum samples under a microscope in field conditions.

The microscope sputum test is most commonly used in developing countries, where there is a disproportionately high incidence of TB. As well as being unreliable, this test must often be repeated on three occasions to yield reliable results.

Currently, the new blood test uses an expensive tool known as ELISA to detect levels of biomarkers. Scientists aim to develop the method into a simple ‘dipstick’ test that will be cheap, accurate and produce quick results.

Professor Sanjeev Krishna, Professor of Molecular Parasitology and Medicine at St George’s, has been leading the research. He said: "We are putting forward a completely fresh approach to look at an ancient problem. I think it is going to be very exciting to make this work in clinics where a test for TB is desperately needed. The next stage will be to use the biomarkers we have identified to develop a cheap, accurate and rapid diagnostic test that can be used easily and quickly out in the field."

About one-third of the world’s population carries the TB bacterium, Mycobacterium tuberculosis. A tenth of these will later develop the debilitating lung illness, often because their immune system is compromised by HIV infection or cancer.

"Improving diagnostic accuracy will have a massive impact on managing TB," says Professor Krishna. Treatment is a lengthy, costly process: patients must take four different antibiotics for two months, followed by two antibiotic drugs for a further four months.

"If a clinic could rule out TB infection reliably using these types of tests, this would enable valuable resources to be targeted at the patients who need treatment," Professor Krishna explains.

The initial results of the test were published in The Lancet last September.

Ends

Notes to Editors

World TB Day is on 22 March 2007.

Professor Sanjeev Krishna is available for interview. Contact communications manager Tamsin Starr on 0208 725 1139; 07786 982028 or at tstarr@sgul.ac.uk.

St George’s, University of London is the only independently governed medical school in England and provides training to a wide range of healthcare students on one site. As well as providing courses in medicine and biomedical sciences, the Medical School also offers courses in midwifery, nursing, physiotherapy, radiography and social work in conjunction with Kingston University. The school is extremely active in research and has a high reputation in areas such as infection as well as diseases of the heart and circulation. Other areas of expertise include stroke rehabilitation, air pollution and addictions.