First paper test for three diseases at once
A quick, paper-based blood test which can simultaneously detect the
Ebola, dengue and yellow fever viruses has shown promising results in
tests, say researchers from the Massachusetts Institute of Technology
(MIT) in the United States.
The device, which looks similar to a commercial pregnancy test and
comes with a US$5 price tag, was presented at a conference of the
American Chemical Society on 18 August.
The test combines coloured silver nanoparticles with antibodies
against each of the three viruses. If a patient has the corresponding
virus in their blood, the test pad shows a disease-specific colour
within a few minutes.
At the moment, healthcare workers use genetic techniques to examine
the DNA in a blood sample and identify a particular virus. This takes
several hours and requires a stable laboratory environment.
In contrast, doctors and health workers could use the paper test to
detect disease even in remote areas with no power supply or hospital.
However, it is not sensitive enough to replace traditional laboratory
tests altogether, and the researchers say that follow-up tests in a
clinical environment would be needed to confirm the test's diagnosis.
Doctors could also help to map the spread of a disease by taking
pictures of the test results and uploading them to an online database.
"Because of the GPS and time and day stamp associated with the photo,
this map would show where the disease is spreading, or where it is dying
out," says Kimberly Hamad-Schifferli, an associate professor at MIT.
This could help health authorities to identify and confirm disease
outbreaks in rural areas, says Jennifer Norman, Director, Public Health
at the UK humanitarian organization, Mercy Corps. "For example, if
several patients tested positive for Ebola using this rapid test, health
officials could prioritize further diagnostic and human resources for
that particular area," Norman says.
So far, the device has only been tested using blood samples with
added viral proteins rather than actual patient samples. The MIT team is
awaiting approval from the US Food and Drug Administration to begin
tests in Ebola-affected areas, and hopes that the test can be used
widely within a year.
The researchers used 3D printers to manufacture the test themselves,
so it is available in only limited quantities for now. The safe disposal
of used tests also requires consideration.
"The amount of nanoparticles in a single test is small but the used
test may need to be treated as hazardous material," says
Hamad-Schifferli.
Mirva Helenius, a Red Cross spokesperson who works in Ebola-stricken
Liberia, says the paper test could be useful, but efforts "must continue
to focus on what we know works in reducing Ebola cases. This includes
reporting cases in a timely way, tracing patients' contacts and avoiding
practices such as traditional burials that can promote contagion,
Helenius says.
-SciDev.Net |