*As mobile phones become common worldwide, study sees potential for
ubiquitous device to fight parasites that infect 2 billion people and cause
malnutrition in children*
DEERFIELD, IL. (MARCH 11, 2013)— Scientists working in rural Tanzania have
used a simple US$8 glass lens, a strip of double-sided tape, and a cheap
flashlight to convert an Apple iPhone into a field microscope that can
successfully detect intestinal worm infections in children, according
to a study
published today
by the American Journal of Tropical Medicine and Hygiene.
“There’s been a lot of tinkering in the lab with mobile phone microscopes,
but this is the first time the technology has been used in the field to
diagnose intestinal parasites,” said Isaac Bogoch, MD, an infectious
disease specialist at Toronto General Hospital and the study’s lead author.
The scientists used the cell phone microscope, along with a standard light
microscope, to evaluate 199 children’s stool samples that had been prepared
on a typical laboratory slide. The children were participating in a
clinical trial on Pemba Island in Tanzania that was testing the efficacy of
different drug treatments for getting rid of intestinal worms.
To examine a stool sample, the researchers covered the slide in
cellophane, used double-sided tape to attach it to the camera, lit it from
underneath with the flashlight, and then took a photograph.
Though the iPhone microscope was not as sensitive as a light microscope—the
gold standard for detecting intestinal worms in stool samples—Bogoch and
his colleagues believe that, with a few adjustments, it can come very
close. “We think cell phone microscopes could soon become a valuable
diagnostic tool in poor, remote regions where intestinal worms are a
serious health problem, particularly in children,” he said.
Overall, the cell phone microscope detected evidence of intestinal worm
infections (by revealing the presence of eggs) in about 70 percent of the
samples that had been deemed infected via a light microscope.
The sensitivity of the cell phone microscope varied greatly depending on
the type of worm and the intensity of infection. It detected 81 percent of
infections with giant roundworm (*A. lumbricoides*) and 54 percent of
roundworm infections (*T. trichiura* ). However, it revealed only 14
percent of all hookworm infections, which the researchers attributed to the
fact that the hookworm infections had left far fewer eggs than the other
parasites.
“It was quite successful at detecting moderate to heavy infections but not
very good at detecting mild infections where there might be only a few eggs
in the sample,” Bogoch said.
Intestinal worms such as hookworms and roundworms, also known as
soil-transmitted helminths, infect some two billion people worldwide. The
burden of disease is particularly high in remote, impoverished regions of
developing countries where they can hinder physical and mental development
in children by causing chronic anemia and malnutrition. However, if quickly
diagnosed, there are several relatively inexpensive drugs available that
provide effective treatment. But detection typically involves examining a
stool sample with a conventional light microscope, a device that costs
about $200 and requires electricity.
For the study, Bogoch and his colleagues sought out an alternative tool by
taping a 3 millimeter ball lens to the camera of Bogoch’s Apple iPhone 4S,
which he used because he already owned one. But he said that any cell phone
equipped with a camera that has a zoom option should work equally well.
Ball lenses are commonly used in the telecommunications industry in
couplings for optical fiber cable. They can be purchased from commercial
suppliers for about $8 to $10.
In place of the microscope’s electric light, the researchers used a small
flashlight that requires a single battery for several hours of operation.
They estimate the entire set-up can be put together in about five minutes
at a cost of less than $15 beyond the cost of a phone.
Bogoch and his colleagues, who include scientists from Massachusetts
General Hospital in Boston and the Swiss Tropical and Public Health
Institute in Basel, believe that a “mobile phone microscope would likely be
of clinical use when it is sensitive enough to detect 80 percent of
infections.” And they note that there are new approaches to cell phone
microscopes under development that should meet or exceed this threshold.
“I’m confident that in the near future we will see cell phone microscopes
widely used in low-resource settings,” Bogoch said. “They’re easy to make,
portable, and today, you can find mobile phones with cameras even in some
of the most remote regions in the world.”
He sees the devices as useful for diagnosing and treating individual
patients suspected of harboring worm infections and for monitoring the
prevalence of disease in the broader population. For example, one approach
to addressing the high burden of worm infections in certain regions is to
simply administer drug treatment to everybody. Bogoch said cell phone
microscopes could provide a simple and inexpensive way to conduct the
disease surveillance required to evaluate the effectiveness of these
so-called MDA (mass drug administration) campaigns.
“I have nothing but praise for the ingenuity of scientists using all
available tools to solve pressing health problems in some of the poorest
parts of the world,” said David H. Walker, MD, president of the American
Society of Tropical Medicine and Hygiene. “This study is an illustration of
how a modest investment in tropical disease research can help reap enormous
health benefits for children.”
This research was supported by the Lichtenstein-based Medicor Foundation
and the Swiss National Science Foundation, but neither they nor anyone
associated with Apple played a role in the study design, according to
Bogoch.
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*About the American Society of Tropical Medicine and Hygiene*
ASTMH, founded in 1903, is a worldwide organization of scientists,
clinicians and program professionals whose mission is to promote global
health through the prevention and control of infectious and other diseases
that disproportionately afflict the global poor.
*About the American Journal of Tropical Medicine and Hygiene*
Continuously published since 1921, AJTMH is the peer-reviewed journal of
the American Society of Tropical Medicine and Hygiene, and the world’s
leading voice in the fields of tropical medicine and global health. AJTMH
disseminates new knowledge in fundamental, translational, clinical and
public health sciences focusing on improving global health.
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