Finger-Prick Blood Test Aids Early Tuberculosis Detection and Risk Stratification

Household contacts of people with tuberculosis face an estimated 2% risk of developing disease, yet most are asymptomatic at the time of screening. Early-stage cases are often missed because symptom checks and sputum testing have limited sensitivity for incipient infection. Practical tools that both detect active tuberculosis and estimate short‑term progression risk are needed to guide preventive care. A new study shows that a finger-prick host‑response blood test can aid early detection and short‑term risk stratification.

Ludwig Maximilian University of Munich (LMU), working within the ERASE‑TB consortium, evaluated the Cepheid Xpert MTB Host Response (MTB‑HR) blood test. The technology measures the host immune response rather than detecting Mycobacterium tuberculosis directly, using a three‑gene signature on the GeneXpert platform. Unlike standard tests that detect the bacteria directly, these assays measure the body’s immune response, which may help identify infections earlier and pinpoint people at greater risk of developing disease. Each assessment uses a capillary finger‑prick sample, enabling repeat testing during routine follow‑up.

In a large prospective cohort, investigators assessed more than 2,000 household contacts (aged 10 years and older) across Tanzania, Zimbabwe, and Mozambique. Participants were followed for up to two years with regular clinical, imaging, and laboratory evaluations. At every visit, a finger‑prick blood sample was analyzed with the MTB‑HR assay on GeneXpert.

The assay demonstrated good accuracy for detecting active tuberculosis and clearly distinguished individuals with and without disease. Prognostic performance for future disease was moderate, with the highest accuracy shortly before clinical onset and lower precision for predictions further in the future. The positive predictive value for incident cases exceeded that of currently used immunological tests, although the assay did not meet World Health Organization (WHO) criteria as a stand‑alone screening or predictive tool.

According to the investigators, immune‑based host‑response tests may help identify active disease and pinpoint household contacts at elevated short‑term risk in high‑burden settings where most contacts are asymptomatic. The study indicates that such assays could support more targeted screening and prevention strategies, potentially limiting unnecessary preventive treatment and improving program efficiency. The findings are published in The Lancet Infectious Diseases, and the authors emphasize the importance of evaluating these tools in the real‑world environments where they are intended to be used.

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