Tuberculosis: soon a blood test to diagnose people at risk?

English researchers have developed a blood test that can identify tuberculosis even in patients who have not yet contracted the active form of the disease.

Tuberculosis is an infectious bacterial disease that mainly affects the lungs. In 2016, 1.7 million people died, making it the world's deadliest infectious disease. Because although there is a vaccine to prevent it and it is treatable with antibiotics, the most affected populations are also the most disadvantaged and therefore those with the least access to care.

A quarter of the world's population is a carrier of tuberculosis

In all, about a quarter of the world's population carries the disease. Most often, this has no impact on health. But in 5 to 10% of cases, tuberculosis wakes up. However, a new study published in the medical journal Clinical Infectious Disease could greatly facilitate diagnosis. British researchers have succeeded in developing a potential new blood test that can identify tuberculosis in patients and even at-risk patients.

During their study, researchers from Leicester and Nottingham followed 66 people and divided them into four groups. The first had active pulmonary tuberculosis, the second had a latent form of the disease, the third was suspected of having it, and the third was healthy individuals.

In order to identify the presence of the bacterium causing TB, they submitted the participants to their blood test Actiphage twice, one year apart. Result: Actiphage was able to identify 73% of patients who had already been diagnosed. No participants in the healthy control group tested positive and no patients with tested negative latent tuberculosis subsequently developed an active form of the disease. In contrast, two of the three participants with latent infection tested positive developed the disease more than six months later. Thus, Actiphage could help identify people at risk, say the researchers.

A specific bacteriophage to identify the Mycobacterium tuberculosis

"The most common symptoms of tuberculosis affect the lungs and from there, the disease can spread to others by coughing and sneezing, while there is a lack of tools to diagnose people who can not sputum. coughing of pathological products from the broncho-pulmonary and upper airways, NLDR), such as children, the diagnosis is delayed, which promotes the spread of the disease. disease, "says Dr. Pranabashis Haldar, lead author of the study. It should be remembered, however, that only pulmonary forms of tuberculosis can be contagious.

In addition, the detection of Mycobacterium tuberculosis (MBT), the bacterium causing the disease is limited because grows very slowly, making traditional farming methods ineffective. However, Actiphage uses a specific bacteriophage capable of efficiently releasing DNA from the bacteria and identifying it in just six hours.

"The data from our human study show that after infection, MBT circulates in the blood at levels that were previously undetectable and that the immune system may fail to effectively contain the bacteria in the lungs," says Dr. Catherine Reese, co-author of the study.

Since 2007, the vaccine is no longer mandatory in France

Thus, "our observations give a better understanding of how human tuberculosis develops," say the researchers who hope to one day market their test. If larger scale studies are yet to take place, "this new test has the potential to target those at risk and treat them as soon as possible". "It's very exciting," the researchers conclude.

In France, the health authorities strongly recommend vaccination against tuberculosis, especially in infants who are particularly exposed to the bacillus. This is no longer mandatory since 2007. And today, if the incidence of the disease is low in France, it has not completely disappeared. In 2015, there were still 4,741 new cases reported.

Video: Updated TB Testing and Treatment Recommendations for Health Care Personnel (November 2019).