A $34 device that plugs into the audio jack of a smartphone was nearly as effective as far more costly diagnostic blood testing equipment in identifying antibodies for HIV and syphilis in a pilot study in Africa, U.S. researchers said on Wednesday.
The mobile lab device, known as a dongle, cost $34 to make, compared with more than $18,000 for the gold standard diagnostic equipment. In a pilot study, the device performed all of the mechanical, optical and electronic functions of a lab-based blood test in 15 minutes, using only power drawn from the smartphone.
It was developed by a team lead by Samuel Sia, an associate professor at the Department of Biomedical Engineering at Columbia University in New York.
To test its effectiveness, health care workers in Rwanda used the tool to do finger-prick blood tests on 96 patients, including women who were at risk of passing sexually-transmitted diseases to their unborn children.
The team compared the results with standard enzyme-linked immunosorbent assay or ELISA testing, and found the results were nearly as accurate. The test has a sensitivity of 92 to 100 percent, a measurement of how often the tests accurately identified the target antibodies, and it had a specificity of 79 to 100 percent, an indicator of how well the test did at ruling out people who were not infected.
"Our work shows that a full laboratory-quality immunoassay can be run on a smartphone accessory," Sia said in a statement.
The researchers estimate that with syphilis, a test with only 70 to 80 percent sensitivity and specificity that was performed at the point of care could reduce deaths tenfold compared with a perfectly accurate lab-based test, because the non-lab test would be more likely to increase syphilis diagnosis.
The study was backed by a grant from the Gates Foundation and several other funders and published on Wednesday in the journal Science Translational Medicine.
The researchers are planning a larger-scale clinical trial with the goal of winning approval by the World Health Organization for use in developing countries.