Phones join war on HIV, syphilis

A device that plugs into the audio jack of a smartphone and costs less than R400 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, US researchers said this week.

The mobile lab device, known as a dongle, costs $34 (R384) to make, compared with over $18000 for the gold-standard diagnostic equipment.

In a pilot study, the device performed all the mechanical, optical and electronic functions of a lab-based blood test in 15 minutes, using just the power drawn from the smartphone.

It was developed by a team led by Samuel Sia, a biomedical engineering professor at Columbia University in New York.

To test its effectiveness, healthcare 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 that the results were nearly as accurate. The test has a sensitivity of 92% to 100%, a measurement of how often the tests accurately identified the target antibodies, and it had a specificity of 79% to 100%, 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.

The researchers estimate that, with syphilis, a test with only 70% to 80% sensitivity, deaths could be reduced tenfold compared with a 100% accurate lab-based test because the non-lab test would increase syphilis diagnosis.

The study was backed by a grant from the Gates Foundation and several other funders and published on Wednesday in Science Translational Medicine.

The researchers are planning a larger-scale clinical trial with the goal of winning approval by the World Health Organisation for use in developing countries.