Rapid, cheap HIV test finds success as first of its kind tested in the field
The first field trial for a “lab on a chip” accurately detected both HIV and syphilis among a Rwandan population.
Blood samples injected into the clear plastic, credit card-shaped device produced results within 20 minutes. This kind of test could offer a faster, cheaper and easier way to detect infectious diseases that afflict developing countries, according to the report published by Nature Medicine.
“This is a big step,” said Doris Rouse, a vice president at RTI International in North Carolina, who specializes in global health technologies and was not involved with the study. “What’s especially exciting about this device is that it’s rugged, easy to use and doesn’t require a lot of infrastructure or training,” she added.
Cheap HIV tests that provide results within 30 minutes have been available for years, but many rely on a decades-old method called lateral flow. A sample of blood or oral fluid is placed on a strip of paper, and like a pregnancy test, a colored band appears and can be interpreted to indicate infection.
Few lateral flow tests, however, have proven reliable across multiple settings and types of infection. Many people in developing countries instead rely on expensive and time-consuming laboratory analysis, “but this [new] test can be done outside the lab with all the same advantages and sensitivity [for detection,]” said Rosanna Peeling, a diagnostics researcher at the London School of Hygeine and Tropical Medicine, who was not part of the study.
The lab on a chip trial shows 100-percent detection of HIV-positive cases, with only one false positive out of 70 total samples, according to the report. When a dual test of HIV and syphilis was performed, the chip had similar accuracy for HIV; 94 percent of syphilis cases were detected, though there was a higher rate — four out of 67 total samples — for false positives.
Overall, the test proved successful in a difficult environment with little infrastructure, said Samuel Sia, one of the study’s authors and a biomedical engineer at Columbia University. “We’ve taken what’s long been a great theoretical concept and shown that it can be done in the field,” he added.
Sia tested the device in Rwanda, where about 3 percent of the adult population is infected with HIV, according to the World Health Organization. Currently, patients in the city of Kigali have to provide blood at the local hospital, which then sends samples to a national laboratory for analysis. Turnaround time for results could be days or weeks, but the chip, which can be used at the hospital, detected both HIV and syphilis within 20 minutes.
According to Sia, the chip could also potentially detect hepatitis B and C, herpes, gonorrhea and chlamydia — infections that are often found in combination with HIV and have few reliable and cheap tests available. All infections could be detected on a single device, at the same time and with a small amount of blood — a fraction of a needle prick’s worth.
The chip, which the research team named mChip, is comparable in price to lateral flow tests. Sia estimated his device would cost about $2 to $3; lateral flow tests can cost more than $4 and lack the cost-efficiency of detecting multiple infections. Most lateral flow tests also require interpretation, but Sia is developing a separate reading device — much like an ATM for the credit card-sized lab on a chip — that can provide an easy, yes-or-no diagnosis within seconds.
Gottfried Hirnschall, director of the WHO HIV/AIDS department, wrote in an e-mail that the organization “welcomes this development” of testing technology, adding that these devices “will be particularly useful” in eliminating transmission of HIV and syphilis from mother to child through earlier treatment.
Shiva Goudar, a researcher at Jawaharlal Nehru Medical College in Belgaum, India, helps test for HIV among local pregnant women. He said many patients live two or three hours away from the hospital centers where blood samples are collected, and it can take two days to receive results.
The lab on a chip could be used by primary-care providers within the same village, Goudar said, and “doing this test at the point of care cuts down on the time, effort and logistics of transport for the blood sample.” It would provide a “tremendous advantage” over current testing practice.
Sia presented the chip test at a technology competition for maternal and child health last week in Washington. Sponsored by USAID, the Gates Foundation and others, the “Saving Lives at Birth” challenge will award a total of $14 million to relevant projects. Sia’s lab on a chip is one of 18 nominees for an undecided number of grants to be awarded by the end of 2011.
Funding is crucial for further development of the lab on a chip. A lack of interest from companies is likely keeping the test from reaching the ground within two or three years, Sia estimated, despite excitement from the global health community. “The challenge now,” he added, “is how to go from an academic study to distributing this test in the field.”