Rats to the rescue

Land mines kill or maim upwards of 25,000 people a year and are a major cause of suffering in the developing world, according to the United Nations. The mines are particularly a problem in Mozambique, where a 16-year civil war left the country dotted with minefields, threatening the lives and limbs of thousands of civilians and depriving farmers of livelihoods, says Alan Poling, PhD, a psychology professor at Western Michigan University.

"Either you stay off the land and you may starve, or you go on the land and you may lose a leg," says Poling, an adviser to APOPO, a nonprofit demining organization.

Today, people in Mozambique can safely tread on 100 acres of previously dangerous land thanks to a new demining technology pioneered by APOPO and Poling: rats. After extensive training, APOPO’s giant African pouched rats detect mines in the field with 100 percent accuracy, according to a study by Poling and his colleagues in the Journal of Applied Behavior Analysis (Vol. 44, No. 2). With their keen sense of smell, giant African pouched rats can easily sniff out TNT, but they aren’t heavy enough to trigger land mines, says Poling. Dogs can also sniff out land mines, but rats have some advantages: They are smaller, less expensive to house and feed and resistant to tropical diseases. They also aren’t picky about whom they work for, whereas dogs tend to bond with their trainers.

"Rats work equally well with everyone," he says.

Before heading out to the field, the rats undergo eight months of lab training. First, they learn to dig when they smell a porous metal ball filled with TNT, but not when they sniff balls filled with other substances, such as diesel fuel. Trainers reward rats with a clicker sound followed by a piece of banana. The rats then apply their skills on a simulated minefield, running back and forth on a rope stretched between two trainers. When the rats prove to be perfectly accurate, they graduate to a real minefield.

In addition to clearing land mines, giant African pouched rats may soon tackle an even bigger problem: tuberculosis. Tuberculosis kills about 2 million people each year, and that number is on the rise, according to the World Health Organization. The problem is complicated by ineffective detection in developing-world laboratories.

Rats may be able to help. A study by Poling and his colleagues, in press in the Journal of Tropic Medicine Hygiene, found that rats trained to sniff tuberculosis in samples of human saliva increase the detection rate over standard smear microscopy by 44 percent. In addition, the rats are fast, able to test hundreds of samples a day, compared with a lab technician’s rate of about 40 samples a day.

While rats are often viewed as pests, APOPO’s tuberculosis and land mine projects are changing many people’s perceptions, says Hanoch Barlevi, chief technical adviser for the United Nations Development Program’s Institute of National De-mining. "There was a lot of skepticism about using the rats as operational animals, but so far it’s proven to be a good investment," he says.