It seems to me to that is has taken an inordinate amount of time to develop but we now have a rapid point-of-care molecular test for TB. My expectations were probably too high given the complexity of the goal. Details about the test were revealed recently (see: WHO says Cepheid rapid test will transform TB care). Below is an excerpt from the report:
The World Health Organization (WHO) gave its backing on Wednesday to a new molecular test for tuberculosis made by Cepheid which can rapidly diagnose TB, one of the world's biggest killer diseases. The Geneva-based WHO said in a statement it was endorsing the test because it could "revolutionize" TB care and control by accurately diagnosing patients in about 100 minutes, compared to current tests that can take up to three months to give results....The test, called Xpert MTB/RIF, was developed by Cepheid and the Foundation for Innovative and New Diagnostics (FIND), a non-profit group funded by the Bill & Melinda Gates Foundation, the European Union and national donors. It detects many TB cases missed by current technology, which is more than a century old....Many countries still rely largely on sputum smear microscopy for testing for TB, a diagnostic method developed more than 100 years ago. The new Xpert MTB/RIF is a "while-you-wait" test that can be used outside of conventional laboratories by general health workers and does not require a specialist operator. In a study published in September, researchers said that when used on 1,730 patients with suspected TB and suspected drug-resistant TB, the Xpert test successfully identified 98 percent of all cases. It also identified 98 percent of patients with a form of TB resistant to rifampin, or rifampicin -- one of the most powerful TB drugs -- and achieved these results in less than two hours. The WHO said implementation of this test could result in a three-fold increase in the diagnosis of patients with drug-resistant TB and a doubling in the number of HIV-associated TB cases diagnosed in areas with high rates of TB and HIV.
Obviously, a while-you-wait (also known as point-of-care) test is extremely important for the diagnosis and treatment of infectious diseases, particularly in developing countries. Patients in these countries may travel long distances for care and healthcare workers have a limited time-window to work with them. Having said this, it's also apparent to me that this approach is desirable even in wealthier countries from a number of different perspectives. Reducing the time required between diagnosis and treatment is important in terms of patient education and motivation. Testing can also be performed by less skilled personnel. Look for even more testing using a lab-of-a-chip which may, at some time in the future, supplant the use of central labs for much of the common and esoteric lab test menu. The Xpert chip is a CE-IVD device, conforming to an EU Directive, that can be used to diagnose a whole set of bacterial and viral diseases.