In 2014, the World Health Organization challenged researchers around the globe to develop better diagnostic tests for active tuberculosis, a disease that kills 1 .5 million people every year. Two years later, Stanford scientists have come up with an answer: a simple blood test that can distinguish patients with active TB from those who have latent TB or other diseases, or have been vaccinated.
The test, developed in the lab of Purvesh Khatri, PhD, assistant professor of medicine, works by identifying changes in expression of three genes that occur inside human cells after TB infects the body. It’s reliable for testing adults and children, even when resistant strains of TB are involved, and in individuals who have HIV, whose TB can be missed with traditional tests. It also can be used to monitor patients to see if they are getting better, and to see how well they are responding to different treatments.
Khatri says the test’s high degree of accuracy should be especially helpful in monitoring the effectiveness of treatments during clinical trials. It also has the virtue of simplicity: There’s no need to collect sputum (a task that can be difficult with young children and asymptomatic adults), and it could even work in clinics lacking electricity once solar-powered machines to measure gene expression are available. A paper describing the team’s work was published in February in Lancet Respiratory Medicine.