CHICAGO (Reuters) – Two immune system molecules could form the basis of a new test to quickly detect whether tuberculosis is dormant or active and infectious, US researchers said at the weekend.

"A rapid test that could tell the difference between latent and active tuberculosis would be a major step forward," said Dr. Jason Stout of Duke University Medical Center who presented his findings at the American Thoracic Society meeting in New Orleans.

Doctors could more quickly treat active infections, helping to limit the spread of the disease, Stout said.

Current blood tests can distinguish between people who are infected with TB and those who are not but they cannot tell whether an infection is active or dormant.

It takes a culture test that grows the TB bacilli to show if it is active or not, and that can take weeks.

Stout and colleagues collected blood samples from 71 people with active TB, latent TB or no infection at all.