1 May 2014

It is estimated that worldwide, there are at least 1 million cases of tuberculosis in children under the age of 15 every year. Now, a team of international researchers has discovered a genetic signature in the blood of children with the disease, which they say opens the doors to a “quick and easy” diagnostic test.

Tuberculosis (TB) is an infectious disease caused by a bacterium called Mycobacterium tuberculosis. This bacterium is spread through cough or sneeze droplets passed into the air from an infected person. When inhaled, it can multiply in the lungs. This can cause chest pain and persistent coughing, which often brings up blood.

According to the research team, led by Prof. Michael Levin, director of the Wellcome Centre for Clinical Tropical Medicine at Imperial College, TB is notoriously tricky to diagnose in children. When it is diagnosed, the disease is often in its late stages and has already spread to the brain and other organs, increasing the risk of death.

“Although the disease is treatable, thousands of children still die each year due to late diagnosis and many more are left with damage to their brain, bones and lungs,” says Prof. Levin.

But their study, published in The New England Journal of Medicine, suggests that by looking at 51 specific genes in the blood of children with TB, the disease can be identified in 80% of cases.

To reach their findings, the researchers analyzed more than 2,800 children from Malawi, Kenya and South Africa. All children had been admitted to the hospital with symptoms of TB. They then established which children had proven TB and which children had been cleared of the disease.

The team examined blood samples from South African and Malawian children. They wanted to determine which genes had been switched on or off in those with TB.

Potential for a ‘simple, rapid and affordable’ test for TB

X-ray of lungs
Researchers say the newly discovered genetic signature may lead to a “simple, rapid and affordable” diagnostic test for TB.

From more than 30,000 genes in the human genome, the team found that they were able to distinguish TB from other diseases by looking at only 51 genes and seeing whether these were activated or suppressed.

The researchers tested this genetic signature in the Kenyan children and came up with a TB risk score. This score accurately diagnosed TB in more than 80% of the children.

Prof. Levin says the team’s findings demonstrate the potential for a quick and easy test for earlier diagnosis of TB.

“What we now need is collaboration from biotechnology and industrial partners to turn these findings into a simple, rapid and affordable test for TB that can be used in hospitals worldwide,” he adds.

According to the World Health Organization (WHO), more than 95% of deaths from TB occur in low- and middle-income countries, such as South Africa, emphasizing the need for better diagnostic tools for the disease.

Co-author Prof. Brian Eley, of the University of Cape Town in South Africa, says:

“An accurate test for childhood TB would be an enormous breakthrough, enabling earlier diagnosis, reducing long hospital admissions for investigation of TB suspects and limiting the number of children treated inappropriately.”

Earlier this year, Medical News Today reported on a study detailing the “alarming” spread of drug-resistant TB, which affects more than half a million people worldwide every year. The researchers of this study note that until more effective treatment combinations are found, the chances of surviving this type of TB are “dismal.”

Another study suggested that in South Africa, people with drug-resistant TB are being discharged into the community, which is contributing to the spread of the disease.


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