© Parkin Parkin

As a boy, growing up in Antwerp, Belgium, Weetjens had kept pet rats. “Not only rats – I was very fond of all kinds of rodents. Hamsters and mice, and then rats. I tried gerbils and squirrels as well.” He bred them in his bedroom. “I learned that they smell very well, but I was not occupied with that. I was simply breeding these animals to give offspring to the pet shops. It was a way to get pocket money. I gave up all rat breeding in my bedroom when I was 14.”

After graduating and starting work as a product designer, Weetjens found himself increasingly preoccupied with the problem of landmines. “I saw a documentary about Cambodia, and also Princess Diana in Angola visiting mine-extraction operations. These two things triggered in me the magnitude of the problem.” He began to consider landmine-detection systems: in theory, what kind of engineering solution would work best? Then he met a Dutch researcher who had come across stalled plans to try to use cockroaches to detect TNT exuding from buried landmines. “I thought, yes – this was the way forward: using local resources, a solution based on what was available in the context. This was for me an a-ha moment.”

Except that Weetjens didn’t think cockroaches. He thought rodents. In 1997, at a time when the local military academy was working on a landmine-detecting robot, he secured his first research grant, from the Belgian Development Cooperation, a government agency. “The secretary for the Development Cooperation had been a director of Doctors Without Borders. He knew the African realities much better than the army folks, actually. He immediately said to one of the professors in our team: ‘This is a stupid idea, let’s do it!’”

There were all kinds of questions to address, not least: which species to use? Ideally, he wanted an animal endemic to sub-Saharan Africa – which at the time was the region most affected by landmines – that wasn’t that susceptible to disease, that relied heavily on scent (because they’d have to sniff TNT in tiny concentrations in the air), that was long-lived and that could be trained. Professor Ron Verhagen, Head of Evolutionary Biology at the University of Antwerp, who had worked in Morogoro for many years, had a suggestion. “He said, well, I might have a suitable animal for you: the African giant pouched rat, which he had seen at some point in a village on a leash.”

There were some early setbacks. At first, the rats didn’t breed well in captivity, and it took a while to work out how best to train them. But the landmine programme, which operates from a base on the campus of Sokoine University of Agriculture, has become hugely successful.

At an average weight of about 1 kg, the rats are too light to set off mines. They can scurry across and search 200 square metres of ground in 20 minutes, compared with 50 square metres per day for a person using a metal detector. Apopo, the organisation Weetjens founded, dispatches trained rats to areas of land known or suspected to be mined (but not too heavily) and which cannot be farmed or lived upon because of the risk of setting off a mine.

Lightly mined regions can also be disproportionately dangerous, because local people are more likely to take the risk of venturing into them. James Pursey, who manages communications for Apopo, tells a story: “I was just in Angola. There’s an area next to a school where a landmine once went off. I was talking to the headmaster and he said if the boys kicked a football into this area they would draw straws as to who would go and get it. None of the boys had been hurt. But when the rats searched the area, they found another landmine.”

The Apopo rats are trained on a practice field a short drive from the headquarters. Early one morning, I catch the ‘rat bus’ – a truck that transports the rats from their kennel – along a bumpy road to a kiosk at the end of a red dirt track. Here, trainers are gathering to collect their blue coats, with the Apopo logo, and water bottles, peanuts and bananas for the rats. When they have everything they need, they head down to the field.

Here, 1,500 deactivated landmines are buried up to 30 centimetres below grass and shrubs. The field is taped off into rectangles, varying in area from 5 x 3 metres up to 10 x 20 metres. The trainers work in pairs, each pair working a different rectangle. They start at one end. The trainee rat wears a harness with a large-bore spring attached to it. A cord runs from one trainer’s boot, through this spring to one of the other trainer’s boots. The rat runs freely along the cord, sniffing the ground as it goes. Tapes are also attached to each end of the spring, and the trainers hold the tapes. They use them to gently tug the rat back into position, or into action if it stops moving for too long.

Once the rat has sniffed the first half-metre’s width of the rectangle, the trainers take a half-metre step to the side, and the rat sets off again. The trainers know where the landmines are. When a rat stops and sniffs and scratches in the right location, one squeezes a clicker (the kind routinely used in training dogs and dolphins) and the animal darts over for a nibble of banana or a nut.

In a real (rather than practice) field, paths for the trainers are first cleared by metal detectors. If a rat sounds the alarm, a trainer puts down a marker, and when the zone has been fully checked, someone with a metal detector goes to the spot to confirm the rat alert.

To graduate as a landmine-sniffer, a rat has to find 100 per cent of landmines in a test field in a single sweep. Abdullah Mchomvu heads the landmine-training team. He’s out here this morning, supervising the session. “You have to be patient,” he says. “Some learn quickly and others more slowly – but all in all they normally reach the goal.”

Apopo rat teams have now worked in Angola, Mozambique, Cambodia, Thailand, Vietnam and Laos, not just on landmines but also on old ammunition, mortars and grenades. The Apopo team working in Mozambique, for example, has destroyed 13,294 landmines and returned over 11 million square metres of land to communities. This programme played a big role in the country’s ability to declare, in September 2015, that it was landmine-free.

Mchomvu started working with the rats in 2002. He has 24 trainers under his supervision. It’s satisfying work, he says. “To train the rats to detect landmines means we save the lives of people. To work at serving other people – I like it.”