New Sensitive Blood Assay Detects Tuberculosis Antigen Directly in Blood

Tuberculosis continues to be a leading global infectious disease, and diagnosis still hinges on sputum samples that many patients cannot produce early in illness. Delays in confirming Mycobacterium tuberculosis facilitate transmission and complicate management. A blood-based method that separates exposure states and detects active disease could accelerate triage when sputum testing is limited. New findings presented at the ADLM 2026 meeting ooutline a sensitive approach that measures a bacterial antigen in blood to identify active tuberculosis.

Taipei Veterans General Hospital investigators evaluated a blood assay that quantifies a biomarker called circulating 6‑kDa early secreted antigenic target (ESAT‑6) with a new biosensor. ESAT‑6 is derived directly from M. tuberculosis. This differentiates it from immune-response biomarkers.

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The researchers measured ESAT-6 in blood from 217 participants who either had an active pulmonary TB infection (cases) or did not (controls). The control groups included patients with lung disease caused by non-tuberculosis Mycobacterium species, patients with lung cancer, individuals with latent tuberculosis after exposure, uninfected exposed contacts, and healthy individuals with no known contacts. Together, the samples represented a spectrum of exposure and disease states.

ESAT-6 effectively distinguished tuberculosis from non-tuberculosis groups and increased stepwise from uninfected exposed contacts to latent infection to active disease. This association persisted after accounting for age, sex, and diabetes, and the marker outperformed two common blood-based markers. Findings were presented July 28, 2026, in Anaheim, California, as Abstract A-097 during the scientific poster session.

“Every week of delay in diagnosing TB matters — so early identification may allow treatment to begin sooner and potentially reduce transmission,” said Dr. Sheng‑Wei Pan, a physician in the department of chest medicine at Taipei Veterans General Hospital in Taiwan and the study’s lead author.

“We are currently planning a prospective study to further evaluate if this can be used in a real‑world clinical setting,” added Dr. Pan.

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Taipei Veterans General Hospital