New Delhi, July 19 -- ST. PETERSBURG - For a patient in a high-burden country presenting with a chronic cough and inflamed lymph nodes, the next step is imaging, then often a biopsy, and then a wait that can stretch weeks. Between tuberculosis and sarcoidosis, two diseases that look nearly identical under a microscope and on an X-ray, clinicians have long relied on that slow and invasive sequence - and still got it wrong four times out of ten.

Researchers at St. Petersburg State University and the Almazov National Medical Research Center say they have found a faster path. The two institutions announced Friday they had developed an algorithm that analyses the ratio of specific immune cells - regulatory T-cells and memory B-cells - extract...