Researchers created a device about the size of a toaster that can test a drop of blood to tell, in about half an hour, who's immune to certain infections and who's not.
The goal is to find groups of people at risk of outbreaks, especially in impoverished and remote parts of the world, in time to save lives. Wednesday, Canadian researchers reported their novel tool worked pretty well at identifying people vulnerable to measles and rubella in a refugee camp in Kenya.
"We're very excited about the potential for this technology," said epidemiologist Aimee Summers of the U.S. Centers for Disease Control and Prevention, who helped the Canadian team field-test the device.
And while the device first targeted measles and rubella, "we could imagine having a panel of tests for any type of infectious disease," said University of Toronto professor Aaron Wheeler, the study's senior author.
Vaccine-preventable diseases remain a major problem in developing countries. Measles, for example, killed nearly 90,000 people worldwide in 2016, and 100,000 children are born every year with birth defects due to rubella. Checking when a population is at risk of an epidemic requires sending blood samples to laboratories to measure protective antibodies, immune system substances that signal someone was vaccinated or previously infected. But that's costly, time-consuming and simply not feasible in areas where the nearest lab is hundreds of miles away.
Wheeler works with a technology called digital microfluidics that is potentially cheap and portable, but hasn't been used outside of research labs, he said. Then one day a CDC official called: Was it ready for a real-world test in Africa?
"We science nerds in the laboratory are often not connected to the settings where our technologies might have the most impact," Wheeler said. He jumped at the chance.
Digital microfluidics involves moving minuscule droplets of liquid through a cartridge or "chip" that's lined with a checkerboard of metal electrodes. Applying electrical signals to different electrodes directs the droplets step-by-step through a process that tests the liquid with chemicals or other agents.
This piece of the technology is often called a "lab on a chip." First, Wheeler's team lowered the price of those cartridges from $60 to $6 by producing them with office printers that put down a pattern of ink that can conduct electricity.
But the chips need to be programmed and powered. Next, the team made portable the bulky lab equipment that's normally used to do that — creating a desktop laboratory, built for less than $2,500. Stick in a chip, and they dubbed the finished product a "measles-rubella box."
Carrying four of the boxes and dozens of chips, researchers boarded a plane for the Kakuma refugee camp in northwest Kenya.
Health workers there were conducting mass vaccinations, and the Toronto team took finger-pricks of blood from 144 young children and their caregivers to test their immunity. Additional blood samples were shipped to a Kenyan Medical Research Institute lab in Nairobi for comparison.
While imperfect, the desktop lab could give results in 35 minutes — and matched standard lab testing 86 percent of the time for measles, and 84 percent for rubella, the researchers reported Wednesday in Science Translational Medicine .
The CDC is analyzing results of a second study of the device conducted in the Congo last summer, using an even smaller, cheaper version of the desktop lab. Wheeler's team is developing chips that could test for additional diseases including malaria and Zika.
"We need to develop cheaper and more efficient ways to detect outbreaks earlier," said Dr. Ernesto Marques, a University of Pittsburgh infectious disease specialist who wasn't involved in the study but finds the technology promising. "This may be one step in that direction."
