In the fight against emerging public health
threats, early diagnosis of infectious diseases is crucial. And in poor and
remote areas of the globe where conventional medical tools like microscopes and
cytometers are unavailable, rapid diagnostic tests, or RDTs, are helping to
make disease screening quicker and simpler.
RDTs are generally small strips on which
blood or fluid samples are placed. Specific changes in the color of the strip,
which usually occur within minutes, indicate the presence of infection.
Different tests can be used to detect various diseases, including HIV, malaria,
tuberculosis, and syphilis.
While the advantages of RDTs are significant—better
disease-management, more efficient surveillance of outbreaks in high-risk areas
and the ability of minimally trained technicians to test large number of
individuals—they can also present problems.
“Conventional RDTs are currently read
manually, by eye, which is prone to error, especially if various different
types of tests are being used by the health care worker,” said Aydogan
Ozcan, a UCLA professor of electrical engineering and bioengineering.
To address such challenges, Ozcan and his
colleagues from the UCLA Henry Samueli School of Engineering and Applied
Science and the California NanoSystems Institute at UCLA have developed a
compact and cost-effective RDT-reading device that works in tandem with
standard cell phones.
“What we have created is a digital
‘universal’ reader for all RDTs, without any manual decision-making,” he
said.
The RDT-reader attachment, which clips onto
a cell phone, weighs approximately 65 g and includes an inexpensive lens, three
LED arrays and two AAA batteries. The platform has the ability to read nearly
every type of RDT. An RDT strip is inserted into the attachment, and with the
help of cell phone’s existing camera unit and a special smart-phone
application, the strip is converted into a digital image.
The platform then rapidly reads the
digitized RTD image to determine, first, whether the test is valid and, second,
whether the results are positive or negative, thus eliminating the potential
errors that can occur with a human reader, especially one administering
multiple tests of various test types. And because the color changes in RDTs
don’t last more than a few hours in the field, the ability to store the
digitized image indefinitely provides an added benefit.
After this step, the RDT-reader platform
wirelessly transmits the results of the tests to a global server, which
processes them, stores them and, using Google Maps, creates maps charting the
spread of various diseases and conditions—both geographically and over time—throughout
the world.
Together, the universal RDT reader and the
mapping feature, which have been implemented on both iPhones and Android-based
smart-phones, could significantly increase our ability to track emerging
epidemics worldwide and aid in epidemic preparedness, the researchers say.
“This platform would be quite useful
for global health professionals, as well as for policymakers, to understand
cause–effect relationships at a much larger scale for combating infectious
diseases,” Ozcan said.
The research is published in Lab on a Chip.
