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New Ways for Poor Countries to Diagnose Infectious Diseases

searchers suggest a substitute for human blood used in tests. And a cell phone microscope can take images of malaria and TB organisms. Transcript of radio broadcast:

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 and horses.

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 infection."

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 I'm Steve Ember.