A research group in the US has come up with a new way to use light to trace tuberculosis (TB) bacteria in fluids.

Diego Krapf, professor at Colorado State University, who led the research, says it is a technique that can be used to detect TB in the developing world, where it is most prevalent.

The low cost, easy-to-use technique, developed by Krapf, Barbara Smith and colleagues, would just require someone to smear a drop of blood or urine on a glass slide, insert it into a machine and read a simple display that would indicate infection.

The CSU development could one day play a role in curbing the spread of TB. Currently, finding people who are infected is not so simple. Doctors can spot suspected cases by taking chest x-rays, which may reveal evidence of infection in the lungs. Or they can turn to a century-old technique called a sputum smear, where a sample of coughed fluid is stained and examined under a microscope for indications of the infection. Better yet, if doctors can grow cultures of TB bacteria from lung fluid, they can definitively know that a person is infected.

These tests may not detect latent TB infections because people who are latently infected may not have enough bacteria in their lungs to detect. These findings will be presented at the Optical Society’s annual meeting, Frontiers in Optics (FiO), next week in San Jose, California.