Global Health: Technology enables faster, less expensive TB tests
By Susan D. Hall :
New technology could net results from tuberculosis tests faster and less expensively than currents methods, according to research recently published in the journal Scientific Reports. As an added bonus, the method also could more quickly determine whether the TB strain is drug-resistant.
Current tests require a harmless protein produced by Mycobacterium tuberculosis to be injected under the patient’s skin. The patient then must return two or three days later for a “reading”–a check of whether or not the injection site is red and irritated.
Nanomedical engineer Lidong Qin, the report’s principal investigator, said in an announcement that the new method requires the patient to come in just once.
“Current TB testing techniques take at least two days, and always require the person to be present,” Qin said. “And if a person has ever been exposed to TB, even if they don’t have an active TB infection, their test will be positive for infection. In as little as one day, we can identify the species of bacteria by isolating single cells. Our method also distinguishes between past and active infections of tuberculosis.”
The new technique uses silicone wafers pocked with thousands of tiny wells that isolate the bacterium. Slides covered with antibodies to the TB protein ESAT-6 are placed atop the wafers and cultured at body temperature for 24 to 48 hours, time enough for the bacteria to react and produce waste. The wafer and slide then are separated and analyzed.
Under fluoroscopic analysis of the wells, TB will appear bright green. Reaction to antibodies on the slide can determine whether it’s a drug-resistant strain.
The new method allows both tests to be done at the same time, rather than the three to six weeks now required to identify the strain.
The new tests now cost $10, but mass production could bring that down to $1, said Qin, adding that the technology isn’t quite ready for the market yet. Current tests run $4 to $6 each.
Drug-resistant strains of TB are on the rise and raising concern. The Wall Street Journal recently highlighted the story of a woman from India whose disease has been all but incurable.
E-health technologies–including phones, computers, and text messages–are gaining ground in developing nations, the World Health Organization reported in May, with tuberculosis care among types of services most likely to have an e-health component.
The mHealth Alliance and Stop TB Partnership have teamed up in the fight against TB using software and mobile devices in a host of new ways.