Long a dream, it's now real: a fast and accurate TB test that doesn't need phlegm

A scanning electron micrograph of Mycobacterium tuberculosis bacteria, which cause TB. BSIP/Universal Images Group via/ hide caption toggle caption BSIP/Universal Images Group via/ TB or not TB? That has been the question for nearly 150 years, when Dr. Robert Koch first identified the rod-shaped bacterium that causes tuberculosis. This serious respiratory illness is currently the world's deadliest infectious disease , killing more than a million people a year. The most common test to determine if someone has tuberculosis hasn't really changed since the late 1800s. The process relies on phlegm. "It's a nasty substance," says Adithya Cattamanchi , a pulmonologist at UC Irvine. "No one likes it, right? You don't like to cough it up. Health workers don't like to work with it. It's difficult to work with in the lab because it's so viscous." In addition, not everyone can produce phlegm easily, including children, the elderly and those weakened by disease. The phlegm is then examined under a microscope for the telltale tuberculosis bacteria. But the test is imperfect and imprecise. Sometimes patients are told they have TB when they don't. And about half the time, the test misses actual TB cases. "So for a long time, we have been trying to make the diagnosis of tuberculosis easier, cheaper, and quicker," says Alfred Andama , a microbiologist at Makerere University College of Health Sciences in Uganda. …