New Ways for Poor Countries to Diagnose Infectious Diseases

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.

两项新发现为发展中国家辨别传染病提供了更简易的方法。

第一个方法与绵羊有关。研究人员发现无绒毛羊是诊断人们传染性疾病测试所需的血液的良好来源。

在发达国家，微生物学家使用毛用羊或马的血液来进行这种测试。但是对发展中国家来说成本太高。所以，测试通常用人血来代替。

来自加利福尼亚斯坦福医科大学的Ellen Yeh是这项研究的作者之一。她解释了用人血做测试的一系列问题。

Ellen Yeh：“首先，在传染病方面有一定的风险，因为如果使用人血，会有一些列可传播的疾病。尤其是，在非洲，你肯定会担心艾滋病毒等问题。使用人血做血液培养皿的另外一个问题是测试结果并不精确。”

Yeh医生说，使用人血所做测试可能产生错误的结果，所以，结果是不可靠的。

这项研究发现，无绒毛羊的血液是优良的代替品。使用这种血液进行测试产生的结果与使用毛用羊和马的结果相同。

同时，无绒毛羊不需要像毛用羊那样需要特殊照料。由于它们没有那么多毛，能够更好地适应炎热干燥的气候。还意味着不需要为他们剪毛。

Ellen Yeh：“为羊修剪羊毛非常浪费人力物力。使用无绒毛羊的另外一个优势是，它们对寄生虫的抵抗力更强，更不容易被传染疾病。”

科学家还发现了准备和处理血液更加简易，成本更低的方法。他们发现这种新方法效率很高。血液可以直接采集入袋中，就像人类献血一样。

该研究发表在上个月的《公共科学图书馆·综合》(PLoS ONE)杂志网络版上。

该期刊上个月还发表了一篇关于新的实验设备CellScope的报告。CellScope是一种手机显微镜。伯克利加利福尼亚大学的工程师发明了这个设备。

他们在固定在手机上的支持物上面粘附了微型显微镜。手机上的摄像头能够摄取血液和唾液中疟疾寄生虫和肺结核细菌的彩色图片。该研究团队使用特殊的染色和光照技术使图像更加明亮。

图像可以通过无线方式传送给远程科学家进行诊断。

Dan Fletcher是CellScope研发团队的负责人。他指出，世界上许多贫穷地区医院很少，然而手机网络发展却很好。