AUDIE CORNISH, HOST:
Some inventors want to invent things that will make them rich; others have loftier goals. As part of an occasional series called Saving The World One Invention At A Time, NPR's Joe Palca has this report about a new device its inventor hopes will help eradicate cholera.
JOE PALCA, BYLINE: Cholera is a global problem mostly affecting poorer countries. The World Health Organization estimates that as many as 4 million people a year get cholera and about 95,000 die. It's caused by the vibrio cholera bacterium. You can get cholera by drinking water contaminated with the bacteria.
KATHERINE CLAYTON: What we're looking for in our device is the presence of a toxin gene that is associated with the cholera that you see in really, really big outbreaks.
PALCA: That's Katherine Clayton. She's talking about a device she and colleagues at Purdue University invented for rapidly detecting cholera bacteria in water. The idea is to find potential sources of an outbreak. Right now, most tests for cholera require time and a well-equipped laboratory. Clayton's device is small. It's built around a smartphone but works like a portable laboratory.
CLAYTON: It has heating units. It has lenses. And it has a phone to do a lot of image processing.
PALCA: The mini lab has chemicals that will make more copies of something in cholera bacteria called the toxin gene, a process called amplification.
CLAYTON: When you amplify a gene, it makes a solution more viscous like honey.
PALCA: So you take a water sample, put it in the device and wait about 30 minutes. If the sample becomes more vicious, you found the harmful bacteria. But cholera experts have pointed to issues with Clayton's device. One is it only samples a tiny drop of water. And it could happen to be a drop with no bacteria in it even taken from contaminated water supplies. Clayton says they are working on what she calls a concentrator.
CLAYTON: So that we can take bigger volumes of water and concentrate it down.
PALCA: Making it easier to find the cholera bacteria even if it's only there in low levels. Another question some epidemiologists have raised is, will it work in places where it's needed? Clayton says they've done some initial field testing in Bangladesh, and more is planned for the fall. And scientists still aren't sure how and when and whether contaminated water will actually lead to an outbreak. Clayton says having a simple, portable test could help explore that issue.
CLAYTON: I think it's going to start answering some of these scientific questions about how cholera works and about how it's transmitted and about how it shows up in the water.
PALCA: Clayton and her colleagues have formed a company to develop the device. But she knows making a cholera test doesn't put her on a fast track for financial success. Instead, she says her background in engineering has made her feel a sense of obligation to help find solutions to global problems.
CLAYTON: That's really what I enjoy knowing could happen and what the future could look like.
PALCA: Joe Palca, NPR News.
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