Berkeley engineers invent a cell-phone microscope.

What the world needs now—besides love, of course—is a new technology for diagnosing infectious disease that's inexpensive and portable yet highly effective. The World Health Organization estimates that there were about 247 million cases of malaria in 2006 and more than 9 million new cases of tubercellscopeculosis in 2007, with African countries bearing most of the burden in both cases. Fortunately, a group of engineers at UC Berkeley may have come up with the very thing, a device they call the CellScope, a simple attachment that clips onto the back of an ordinary camera phone and turns it into a portable and easy-to-use microscope capable of visualizing single-celled pathogens like malaria parasites or tuberculosis bacteria—no laboratory required.

That's a good thing, because well-outfitted labs are often hard to come by in the developing world. The conditions are usually hot, and electricity may be spotty at best. Put simply, the best medical technologies require clean, air-conditioned labs stocked with bulky machines and endless shelves of reagents—not what a public-health worker is likely to find in places like sub-Saharan Africa and the jungles of Southeast Asia. In such locations, diagnoses used to be based solely on the observations of sparse medical personnel. Then basic microscopes become more common, making diagnosis more of a science. And in the past 15 years or so, strip tests, which work much like pregnancy tests but diagnose various infectious diseases, have become an important tool in the Third World.

But these methods are far from ideal, says Bernhard Weigl, group leader of diagnostics development teams at PATH, a Seattle-based global health organization. In field conditions, basic microscopy yields false negatives about half the time, partly due to poorly trained technicians, and strip tests have a bad rap because their quality is variable—some types are very effective, others are nearly useless.

The CellScope's engineers and the public-health groups that will help test it are optimistic that the device could be a solution. It all began in a Berkeley bioengineering class taught by Daniel Fletcher. To make things interesting, Fletcher presented his students with a challenge: if you were hiking in a remote village where an unknown infectious disease was spreading, what could you build with only a camera cell phone and a backpack of lenses that might help identify the disease? In response, his students developed a prototype CellScope, and the research seemed promising enough that some of the students continued working on it with Fletcher after the course ended (the research was described in this report, recently published in the journal PLoS ONE).

According to Fletcher, CellScope users will be able to take diagnostic images of blood or sputum samples and then either send them off for further analysis using the phone's wireless connectivity, or analyze them independently using image-analysis software that could be installed on the cell phone. In addition to being more portable, the CellScope may prove to be more valuable for diagnosis than basic compound microscopes. That's because the device is capable of fluorescence microscopy, which produces images that are much easier for a layperson to decipher. It's like picking out bright stars from a dark sky, says David Breslauer, a bioengineering graduate student at Berkeley and member of the CellScope team.

Weigl expects that the CellScope will be practical for field diagnoses of malaria and other parasites. He is hopeful that the CellScope could be more effective than test strips, which cannot differentiate between someone with an active infection and someone who was previously infected but has recovered. Furthermore, the CellScope should be able to detect malaria at an earlier stage of infection than test strips. Although the CellScope could be used to diagnose TB as well, Weigl cautions that this could not be done without a lab, given how infectious the disease is. Unlike malaria, which cannot be contracted from blood, a person could contract TB simply from handling an infected sputum sample.

Fletcher says that specialized versions of the CellScope could be tailored to specific uses. A low-resolution version could be used to examine the skin for malignancies, or an otoscope version could allow a mother, for instance, to examine her children's ears for infections and to take a series of pictures that could be sent via cell-phone picture messaging to the doctor for a professional opinion. "You can imagine a suite of little attachments that had different applications," Fletcher explains.

While the CellScope is likely to fill a need for more effective microscopy in the field, experts say that the long-term trend will probably be toward higher-quality rapid test strips and nucleic-acid-based methods for diagnosing disease in the developing world. Commonly used for establishing identity in criminal investigations and for diagnosing disease in developed countries, nucleic-acid techniques involve amplifying and detecting the DNA of various disease-causing pathogens. It's a very precise and specific method of detecting disease, but the challenge is making it portable and cheap enough for use in the Third World. Many research groups are working to overcome these hurdles, and much progress has already been made.

In the meantime, Weigl says, simple devices like the CellScope may be just what the harried, developing-world doctor ordered.

[By Ian Yarett | Newsweek Web Exclusive]

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