Smartphone accessory tests for HIV, syphilis
Researchers have developed a low-cost smartphone accessory that can be used at the point of care to test for HIV and syphilis infection within 15 minutes, according to a study published in Science Translational Medicine.
The accessory, or dongle, performs like an enzyme-linked immunosorbent assay (ELISA) but requires no stored energy — it draws its power from the smartphone. The low-weight device is capable of simultaneously detecting HIV antibody, treponemal-specific antibody for syphilis and nontreponemal antibody for active syphilis. It has an estimated manufacturing cost of $34, compared with a typical benchtop ELISA, which can cost as much as $18,450 per unit, according to study researcher Samuel K. Sia, PhD, associate professor of biomedical engineering at Columbia University School of Engineering and Applied Sciences.
“Our work shows that a full laboratory-quality immunoassay can be run on a smartphone accessory,” Sia said in a press release. “Coupling microfluidics with recent advances in consumer electronics can make certain lab-based diagnostics accessible to almost any population with access to smartphones. This kind of capability can transform how health care services are delivered around the world.”
Sia and colleagues recently conducted a pilot study in Rwanda, where health care workers (HCWs) used the device to test whole blood obtained via finger prick from 96 patients attending prevention of mother-to-child transmission clinics or voluntary counseling and testing centers. The HCWs were given 30 minutes of training, according to the researchers, who said the dongle app included step-by-step pictorial directions, built-in timers to signal the next step in the testing process, a user-friendly interface, and records of test results for later review.
Source:Samiksha Nayak, Columbia Engineering
The dongle is activated by pressing a rubber bulb on the device. The bulb creates a negative pressure chamber that moves a sequence of reagents pre-stored on a disposable cassette. This innovation eliminates the need for an electrical pump required of most laboratory-based ELISAs, which may be particularly helpful in settings with intermittent or no electricity. The device also uses a standard audio jack for transmitting power, making it compatible with iPhones and Android smartphones.
In a masked experiment in which laboratory results were unknown until all testing was completed, the Rwandan HCWs obtained diagnostic results in 15 minutes with a sensitivity and specificity of 100% (95% CI, 59-100) and 91% (95% CI, 83-96), respectively, for HIV; 77% (95% CI, 46.2-95) and 89% (95% CI, 80.4-95) for treponemal syphilis; and 80% (95% CI, 28.4-99.5) and 82% (95% CI, 73-89.6) for nontreponemal syphilis.
In a patient survey, 97% of HCWs said they would recommend the dongle because of its fast turnaround (57%), its potential to detect multiple pathogens (44%) and the simplicity of the process (29%).
“Our dongle presents new capabilities for a broad range of users, from health care providers to consumers,” Sia said in the release. “By increasing detection of syphilis infections, we might be able to reduce deaths by 10-fold. And for large-scale screening where the dongle’s high sensitivity with few false negatives is critical, we might be able to scale up HIV testing at the community level with immediate antiretroviral therapy that could nearly stop HIV transmissions and approach elimination of this devastating disease.” – by John Schoen
Disclosure: Linder and Steinmiller are employees of OPKO Diagnostics, which supplied the cassettes and reagents.