This is the VOA Special English Development Report.
Two new discoveries could offer easier ways to identify
infectious diseases in developing countries.
The first involves sheep. Researchers have found that
hair sheep are a good source of blood for use in tests to diagnose infectious
diseases in people.
In developed countries, microbiologists do these tests
with blood from wool sheep or horses. But for developing countries, that costs
too much. So tests often use human blood instead.
Ellen Yeh from the Stanford University School of
Medicine in California was one of the authors of the study. She explains the
problems with using human blood.
ELLEN YEH: "First off, there is the infectious
disease risk because if you use human blood there's a lot of transmissible
diseases. In particular, in Africa, you'd be worried about things like H.I.V.
The other big problem with using human blood for making these blood agar plates
is that they're actually not accurate."
Doctor Yeh says tests with human blood can produce the
wrong results, so they are not dependable.
The study found that blood from hair sheep is an
excellent substitute. It produced the same results as tests using wool sheep
Also, hair sheep require less care than wool sheep. They
could better handle hot, dry climates because they do not have a lot of wool. It
also means they do not need to be sheared.
ELLEN YEH: "Having to shear the sheep for wool is
actually very costly and labor intensive. The other advantages of hair sheep
include that it's more resistant to parasites, so they're less prone to
The scientists also tested an easier, cheaper way to
prepare and process the blood. They found this new method effective. The blood
can be collected directly into bags, much like with human donors.
The study appeared last month in the online journal
PLoS One, from the Public Library of Science.
The same journal also published a report in July on an
experimental device called the CellScope. The CellScope is a cell phone
microscope. Engineers at the University of California, Berkeley, developed it.
They attached small microscope lenses to a holder
fitted to a mobile phone. The phone's camera was able to take color images of
malaria parasites and tuberculosis bacteria in blood and sputum. The team used
a special dye and special lighting to make the images bright.
The pictures could also be sent wirelessly to distant
experts for diagnosis.
Dan Fletcher heads the team that developed the
CellScope. He notes that many poor areas of the world have few hospitals, yet
have mobile phone networks that are well developed.
And that's the VOA Special English Development Report,
written by June Simms. Transcripts and podcasts of our reports are at
voaspecialenglish.com. I'm Steve Ember.