Tuberculosis still kills 1.4 million people a year, mostly in the developing world. So it is still beneficial to create new diagnostic techniques, especially when they can be used in rural communities. NPR recently reported on a team of scientists who train African giant pouch rats to sniff out the bacterium in patients’ sputum:
The team trains the critters with a Pavlovian click-and-reward approach. When the rats are just a few weeks old, technicians teach the animals to associate a click sound with a small bite of mashed bananas and a special pellet of food. The next step is to link the scent of TB with the reward.
A trained rat can correctly pick out a TB sample about two-thirds of the time, Beyene says. The rate increases to about 80 percent when two or three animals are put on the task.
The rats aren’t as good as a trained pathologist in the U.S. with a microscope, but they get better results than many clinicians working in rural Africa can achieve, Beyene says. “In an African setting, the sensitivity of the microscopy ranges between 30 to 40 percent,” he explains.
So far APOPO only has around 32 rats in their TB program.
Currently the rats are being used to verify positive test results obtained from microscopic samples.