Blood Test Could Soon Replace Sputum Tests in Detecting Tuberculosis

A research team at the Stanford University School of Medicine claims that a simple blood test could soon replace sputum tests in detecting tuberculosis. Researchers explained that getting sputum from a patient is often a daunting task especially when it comes to children or patients that are almost fully recovered.

The team hopes that the recently developed blood test could help diagnose and prevent a disease that kills 1.5 million patients on a yearly basis. Stanford scientists said that their test can detect tuberculosis by looking for a genetic signature that can tell patients affected by active tuberculosis from those with a latent form of the disease or other condition.

Two years ago, the World Health Organization (WHO) underscored the need of a more effective diagnosis tool for active tuberculosis especially in the developing world.

About 9.6 million people learn that they have the disease worldwide every year, and about 1.5 million eventually lose the battle against the disease. Health experts tied the high mortality risk to the fact that tuberculosis remains an infectious disease that is hard to diagnose.

Dr. Purvesh Khatri, lead author of a research paper on the new diagnosis tool, noted that one-third of all people in the world have a form of tuberculosis. He explained that if 10 percent of these people eventually develop active tuberculosis, the number of patients would be huge: about 240 million.

Older diagnosis tools including the skin prick cannot differentiate between active and latent tuberculosis. They can not tell patients that have the disease from those that are no longer sick or have been vaccinated against it. Plus, older tests can misdiagnose tuberculosis in HIV/AIDS patients.

Doctors explained that the traditional way to find out whether a person has the disease is through a sputum test. Dr. Tim Sweeney acknowledged that it is hard to perform the test on demand. For instance, while a patient cannot produce enough sputum, a child cannot be persuaded to follow directions. Additionally, patients that are close to full recovery can no longer provide sputum.

The recently developed blood test on the other hand solves all these hurdles. Furthermore, it can also tell whether a HIV/AIDS patient has the disease or not. Plus it can tell active tuberculosis from its latent form. The test can be performed on both kids and grownups.

While the WHO has said that a tuberculosis test with 66 percent accuracy could prevent thousands of deaths every year, the recent blood test can detect the disease in 85 percent of children. Plus, it is 99 percent accurate when the test is negative.
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