Rats are normally classified as vermin, but they can be heroes too. Proving the fact is APOPO, a Belgian NGO that trains African giant pouched rats to sniff out landmines and tuberculosis infections. Since 2006, these ‘hero rats’ have been working on minefields in Mozambique, clearing the country of over 13,000 landmines, thus reclaiming over 11 million square meters of land. They’ve also accurately analyzed over a quarter of a million blood samples for TB infections.
Bart Weetjens, founder of APOPO, first came up with the idea of training sniffer rats a couple of decades ago, when he was a student at the University of Antwerp. He used to keep pet rodents as a boy, so he knew that they were “very trainable, sociable, and intelligent creatures.” So when he read an article about gerbils being taught to recognise the scent of explosives, it got him thinking.
Weetjens wanted to use his experience of dealing with rodents to find a locally-sourced resolution to the problem of landmines. “I was looking for an appropriate solution that communities at the bottom of the pyramid could use, independent from expensive foreign know-how and technology,” he said. So he placed himself in the situation of the people affected by the problem, and looked at the resources they had at hand.
After considerable research, Weetjens zeroed in on the African giant pouched rat. Although commonly regarded as a pest in most parts of sub-Saharan Africa, he knew that it was the perfect solution, because of its intelligence and extraordinary sense of smell. “For me, this was a natural fix,” he explained.
And he was right. The African giant pouched rat proved easy to train; it cost $6,900 to train each one, which is far cheaper than using humans or dogs. They’re quicker too: humans with metal detectors would take five days to search 200 square meters of land, while the rats can do it in 20 minutes flat. And they are at least a kilogram lighter than the minimum weight required to trip off pressure-activated mines.
APOPO takes good care of its hero rats. There have been zero casualties so far – no rats have died or been injured in the line of duty. Sunscreen is applied to their ears to prevent skin cancer. And once a rat is too old to work, it is retired and permitted to live out the rest of its natural life.
APOPO training manager Abdullah Mchomvu recalls his first day of work, 12 years ago, when he took rookie rats into the minefields of Mozambique’s Gaza province. “On the first day, I was totally afraid,” he said. “There were a lot of skeletons in army uniforms and I was worried that if the rats scratched too hard, they might set off the mines.” But his fears were quickly proved wrong – the rats detected the mines quite accurately, without setting off a single one. “Everything they found was a mine, so that reduced my fear. Now I have no problem going into a minefield. If the rats go into an area and don’t find anything, I’m fine to go in there.”
According to Tim Edwards, APOPO’s head of training and behavioral research, it is important that the rats be trusted. But in the rare event that a rat proves difficult to train, it is removed from the training program, but kept on as a playmate for the rest of the rats. “We do have a range of what people might call personalities in the rats,” Edwards explained. “Usually, any extreme behaviour – either too quick or too slow, or too social or not social enough – can make them a little bit too difficult to train. We see quite a bit of variance, but ideally we have a nice balance between a rat that’s easy to handle but is also active and aggressive enough to go out there and find the mines.”
To ensure that the balance is maintained, the rats are bred from high-performing male mine rats and wild females. Even then, not every rat is cut out for the job. “At each stage, there is a test and the rat must pass the test after a certain number of tries, otherwise it’s deemed unsuitable,” Edwards said. “Some rats do fail and we’re doing dangerous work and we don’t want to put rats into the field that can’t do it.”
But even the rats that fail end up being useful. They’re trained to sniff samples of human sputum, to pick up traces of tuberculosis. The samples, which arrive from various parts of the nation, are first heat-treated to kill pathogens. Then they’re checked in conventional lab tests. If the sputum tests negative for TB, they’re given to the rats, who can detect missed cases of TB. If two rats are able to identify TB in the sample, then it is re-examined in the lab.
According to APOPO, the rats have detected 7,000 TB cases that were missed by conventional tests. This has potentially halted 24,000 infections, and increased detection rates by 45%. “If you consider the number of patients who have been cured of TB because of the rat technology, the impact is huge,” said APOPO microbiologist Georgies Mgode. “A person who suffers from TB loses a lot: they can’t work; they’re stigmatised.”
The usefulness of the rats in medical testing has sparked the interest of the medical community. Researchers are now interested to know of the creatures can be used to sniff for cancer. “We’ve also been contacted about hypoglycemia and some other medical applications,” Edwards said. “There’s so much potential; it’s just a matter of finding the time and the resources to investigate it.”
For now, Weetjens is happy to see his rat program flourish. “In Mozambique, people fought, they laid mines and then they shook hands and went away,” he said. “But they left all those mines behind and they killed farmers. Now our rats are clearing the land and helping people use it again. To me, they are just heroes.”
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