March 15th, 2011 - Open Knowledge
Mar. 15th, 2011
So how did the APOPO founder make the leap from using rats to sniff out land mines to detecting tuberculosis? “Years ago physicians reported that people with tuberculosis had a characteristic odor on their breath and in their sputum,” says Alan Poling, professor of psychology at Western Michigan University. “APOPO is a non-profit committed to humanitarian causes and, in the developing world, tuberculosis is a huge problem. In Tanzania, roughly 75 percent of the people have been exposed to tuberculosis. Weetjens reasoned that if people can smell tuberculosis, certainly rats can. So that was the jumping off point.”
The Giant African Pouched Rat is nocturnal, and makes up for its poor eyesight with an extraordinary sense of smell. According to Weetjens, rats have more genetic material related to the sense of smell than any other mammal species. And though dogs are still excellent scent detectors, the HeroRATs offer several advantages—one being that their noses are always next to the ground just by virtue of their anatomy.
“There are a lot of different ways to detect mines. Dogs are often used and they do a good job. But rats can fill a substantial niche because they’re easier and cheaper to maintain than dogs, and they don’t bond to one person. They’ll work for anybody basically,” Poling comments. In fact, rats can be trained at a fifth of the price required to train a dog in the same capacity and many dogs can’t tolerate the African climate.
Because the rats pause at the positive samples for only a few seconds, they can analyze hundreds of samples in a fraction of the time that humans can do so via other means of analysis. A human can analyze about 40 samples per day using microscopy, whereas the HeroRAT completes that many analyses in seven minutes—a great decrease in detection time and much less expensive! Although the training given the rats is highly effective, Poling comments, “It is just standard operant discriminative training with positive reinforcement. Animal trainers have been using operant conditioning for millennia. They may not talk about it in the same way a behavior analyst would, but they’re good at it.”The rats trained in the cages to detect explosives (mine detection rats or MDRs) are eventually certified in a test mine field seeded with approximately 1,200 land mines of all types. Once the rats pass the field-training challenge in Tanzania they are flown to Mozambique, where they are further trained and tested and eventually accredited as operational mine detection animals. On the job, the rat moves systematically along a rope stretched between two trainers who slowly move down safe lanes as the rat moves back and forth between them while sniffing the ground. When the rat detects a mine, it pauses and scratches the ground. Areas where such responses occur are subsequently searched with metal detectors and any explosive devices that are detected are flagged and remotely detonated by a human crew.
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