Thursday, March 11, 2010

A new tuberculosis detector

One of the problems of detecting tuberculosis in patients is that test results for the disease can take weeks to finish. Researchers in Colorado have developed a portable TB sensor that can give test results in minutes. The prototype was built out of scrap electrical parts from CD and DVD players. The researches hope the device will give patients their life saving drugs sooner.

Tuberculosis claims two million lives a year, most of those come from the under-developed world.

From Scientific American writer Adam Marcus describes the device to us.

This "field friendly" device relies on readily available and relatively low-cost components and can find the lethal pathogen in blood in just 20 minutes, says Diego Krapf, an applied physicist and assistant professor of engineering at Colorado State University in Fort Collins, who designed the new device. That is far faster than conventional methods such as sputum tests, which examine secretions from the lungs and bronchi and can take days—sometimes weeks—to return results. The new detector can identify active infection as well as dormant, or latent, microbes that might one day flare up into full-blown illness, the developers say. It also can distinguish between patients who carry TB and those who once were infected but have successfully fought off the illness.

"Our detector senses proteins, not an immune response against them," Krapf says. "The benefit of doing this is that while proteins mark the presence of disease, antibodies remain in the organism after the disease is long gone." So the new approach greatly reduces the chances of false positives.

A portable detector would greatly aid efforts to fight the infection in developing countries, particularly parts of Asia and Africa where as much as 40 percent of the population carries the microbe, says Robert Belknap, a physician and TB expert at the Denver Health Medical Center in Colorado. "If it works, it's truly portable and doesn't require special conditions, it would be a tremendous advance," he adds.

The device could overcome a few key failings of conventional TB screening. Long delays, in some cases up to six weeks, between test and result often force public health workers to waste time and resources on people suspected of having the infection but who, in fact, do not. Potential patients are frequently isolated—from their children, colleagues and others—for fear that they may spread the disease.

Those suspected of having TB may also be given potent antibiotics as a precaution—drugs that can cause serious side effects, including vomiting, headaches, rash and drug-induced hepatitis (liver inflammation). For these drugs to be effective, and to prevent the body's development of resistant bacteria, patients must take the medications on a strict schedule and complete the regime. The consequences of straying from the regimen are so high that public health authorities try to monitor TB patients to make sure they take their pills, an approach called directly observed therapy. Such programs require substantial money and manpower, and often fail for lack of both.

"An accurate, rapid, point-of-care test would help public health workers better focus resources quickly on the individuals who need it—including providing directly observed therapy—and avoid unnecessary medications and isolation in those who don't," Belknap says.

No comments: