A TB blood test identifies a bacterial marker to distinguish between active and latent tuberculosis infections.<\/p>\n
RT\u2019s Three Key Takeaways:<\/p>\n
A simple TB blood test could accurately\u00a0identify\u00a0tuberculosis\u00a0(TB)<\/a> among patients with varying degrees of exposure to the\u00a0disease, according to new research<\/a>\u00a0presented at ADLM 2026. If confirmed, these\u00a0results\u00a0could\u00a0help save millions of lives\u00a0and curtail a global health\u00a0emergency, researchers say.<\/p>\n \u201cEvery week of delay\u00a0in\u00a0diagnosing TB\u00a0matters\u00a0\u2014\u00a0so early\u00a0identification\u00a0may allow treatment to begin sooner and potentially reduce transmission,\u201d said\u00a0Dr.\u00a0Sheng-Wei Pan, a physician in the department of chest medicine at Taipei Veterans General Hospital in Taiwan and the study\u2019s lead author.\u00a0According to the World Health Organization, a quarter of the global population is estimated to have been infected with\u00a0the\u00a0TB\u00a0bacteria\u00a0(Mycobacterium tuberculosis), and\u00a05-10% will\u00a0go on to\u00a0develop\u00a0active\u00a0disease.\u00a0<\/p>\n TB\u00a0is\u00a0almost always\u00a0curable\u00a0with\u00a0antibiotic\u00a0therapy\u00a0when\u00a0M. tuberculosis\u00a0is detected\u00a0in\u00a0initial\u00a0stages of disease progression.\u00a0It is typically diagnosed by assessing\u00a0samples of\u00a0patients\u2019 sputum,\u00a0which are\u00a0mucus secretions coughed up from\u00a0the\u00a0lungs\u00a0and airways.\u00a0\u00a0<\/p>\n \u201cHowever, not all patients can produce sputum when they first seek medical care, especially those with early disease or those with low bacterial burden,\u201d\u00a0Dr.\u00a0Pan said.\u00a0For that reason,\u00a0non-sputum-based diagnostic tools\u00a0are urgently needed.\u00a0<\/p>\n The researchers evaluated a blood marker\u00a0produced by the bacteria\u00a0called 6-kDa early secreted antigenic target (ESAT-6).\u00a0While ESAT-6 has been studied before, most\u00a0sensors\u00a0used to detect it\u00a0have not been sensitive enough to distinguish active pulmonary TB from latent TB infection, TB exposure,\u00a0or\u00a0other lung diseases.\u00a0Dr.\u00a0Pan\u2019s\u00a0team used\u00a0a new\u00a0biosensor\u00a0that overcame\u00a0this limitation.\u00a0<\/p>\n \u201cThe novelty of our study\u00a0lies in\u00a0the highly sensitive quantification of circulating ESAT-6,\u201d\u00a0Dr.\u00a0Pan said.\u00a0<\/p>\n The researchers\u00a0quantified\u00a0ESAT-6 levels in\u00a0blood\u00a0samples from\u00a0217\u00a0patients who\u00a0either had an active pulmonary TB infection (cases)\u00a0or\u00a0did not (controls). The control group was further classified into\u00a0patients with\u00a0lung disease\u00a0caused by\u00a0different\u00a0Mycobacterium\u00a0species\u00a0than\u00a0the one that causes TB,\u00a0those\u00a0with lung cancer, people infected with\u00a0latent\u00a0TB (no symptoms)\u00a0after\u00a0being exposed\u00a0to\u00a0a contact with TB,\u00a0uninfected people who were exposed to a TB contact, and\u00a0healthy people\u00a0with no known TB contacts.\u00a0\u00a0<\/p>\n The\u00a0ESAT-6\u00a0marker did an excellent job of differentiating between TB- and non-TB\u00a0patients.\u00a0Moreover, the researchers noted a\u00a0stepwise increase in\u00a0the\u00a0blood concentration\u00a0of the marker\u00a0across the spectrum of TB infection, with\u00a0the lowest levels in\u00a0uninfected\u00a0people\u00a0with TB contacts, medium amounts in those with latent TB, and\u00a0the highest levels in patients with active\u00a0TB.\u00a0This\u00a0strong, independent association\u00a0held true even after the researchers\u00a0accounted\u00a0for\u00a0other\u00a0factors that\u00a0could\u00a0impact\u00a0patients\u2019 TB status, such as\u00a0age,\u00a0sex, and the presence of\u00a0diabetes.\u00a0\u00a0<\/p>\n Unlike biomarkers that measure the body\u2019s immune response to infection, ESAT-6 is derived\u00a0directly\u00a0from the TB bacteria.\u00a0\u201cWe believe this is one reason why it performs so well in identifying active TB,\u201d\u00a0Dr.\u00a0Pan said.\u00a0The study\u00a0found\u00a0ESAT-6\u00a0did a better job discriminating\u00a0among\u00a0TB\u00a0patient groups\u00a0than\u00a0two\u00a0common\u00a0blood-based\u00a0markers.\u00a0\u00a0<\/p>\n Because the study used a design\u00a0in which\u00a0patients\u2019 disease status was known from the outset, further research is needed to confirm\u00a0that\u00a0ESAT-6 can predict TB status\u00a0in real time. \u201cWe are currently planning a prospective study to further evaluate if this can be used in a real-world clinical setting,\u201d\u00a0Dr. Pan said.\u00a0<\/p>\n Although sputum cultures\u00a0remain\u00a0essential for\u00a0verifying\u00a0TB and providing information about drug resistance, ESAT-6 holds promise as a practical tool\u00a0for\u00a0triaging\u00a0patients in instances when sputum-based diagnostics are limited or delayed.\u00a0<\/p>\n