The sun is barely up when Thoeun Theap pulls into a clearing in the thick Cambodian bush with a giant African rat on the seat beside him.

In a few minutes the two will be out there beyond the treeline, scouring the earth for the remnants of a war Mr Theap fled almost 40 years ago.

He spends most mornings out here in no man's land with his team of pouched rat handlers from APOPO and de-miners from the Cambodian Mine Action Centre (CMAC). A step in the wrong direction could see them lose a leg.

It takes humans with metal detectors three to four days to clear explosives from a tennis court-sized area, but for APOPO's "hero rats", it's just 30 minutes.

As a Khmer Rouge survivor, Mr Theap got lucky. It's what gets him up before dawn every morning: the drive to clear his country of the explosives that make it hard for Cambodians to access roads, infrastructure and even their own backyards.

For his team of handlers, the "hero rats" are like family.

"I have one favourite rat, his name is Mr Magawa, he's an extra clever one," Mr Theap laughs.

"All the rats are clever but my favourite is him. Rats are calm and when you release them they don't run away.

"After we clear the mines, the people can plant cassava and the kids can go to school without fear," he says.

Like many of his handlers, Thoeun has a close relationship with his "hero rats". ( ABC News: Zoe Osborne )

Born into a war-zone

Born just after the Khmer Rouge took power in 1975, Mr Theap was just one week old when he lost his father to the regime.

"The Khmer Rouge knew my father used to be a soldier fighting against them. They told him to go cut bamboo in another area and he has never come back."

Mr Theap's family struggled on.

"We used to call it a jail without walls," Mr Theap remembers. "All the people in Cambodia were very skinny — big here, but very skinny here," he continues, pointing first to his joints and then to the flesh on his arms.

Under the Khmer Rouge, Cambodia was repressed into an agrarian, communist existence. Individual thought, property and intellectual learning were squashed and every aspect of life was controlled.

"Even if you got married [they] would select your partner for you," Mr Theap says. "After [they] married you they would spy on you that night. If you didn't "get along", they would kill you in the morning."

Escape

When Cambodia was freed from Pol Pot in 1979, the country fell back into conflict and Mr Theap and his older brother fled. Terrified but lucky, the boys reached Thailand after three days of running under the cover of darkness, reuniting with their aunt in a border refugee camp.

After the Paris Peace Accords in 1991, Cambodia's conflict ended and refugees began to return home, only to find their country strewn with explosives.

"We struggled to live," Mr Theap remembers. "There was no safe land. We [farmed it] in fear because we had no choice."

Fed up with the suffering in his community, Mr Theap joined the Cambodian Mine Action Centre in 1997.

Thoeun Theap with one of APOPO rats at the Visitor Center in Siem Reap. ( ABC News: Zoe Osborne )

At that time, Cambodia was one of the most heavily mined countries in the world. There were an estimated eight to 10 million landmines in the country in the early 1990s.

Even today, the country still has the world's highest ratio of mine amputees per capita. Over 64,000 casualties have been recorded since 1979 and many families still live in fear that the land they own may explode under their feet.

"Sometimes we find landmines in a field that a family have dug and ploughed for the last 30 years," says James Pursey, Head of Communications for APOPO.

"It's insane."

Life in a minefield

Tet Sorn and his wife, working on their land. ( ABC News: Zoe Osborne )

Local farmer Tet Sorn has owned 7 hectares of land for decades but only began using it a month ago, after APOPO and CMAC declared it safe. He and his wife are now working by hand to prepare their huge expanse of overgrown scrub for cultivation. "We will plant rice here when the land is ready," he says, smiling.

Until now, Mr Sorn's family grew cassava and raised a few cows on the tiny stretch of soil next to his house. Like many of Cambodia's older generation, Mr Sorn did not receive a formal education owing to the Khmer Rouge's purge of intellectuals. Now, he's unable to find work in nearby Siem Reap, so he has to live from the land.

"In Cambodia, if a family can't use their land they will look for food close to the house," he says.

"We search for food each day just to eat that day. Nowadays there is less food in the bush because many people have already gone looking."

Tet Sorn is excited to begin using his land productively. ( ABC News: Zoe Osborne )

But foraging for food can be just as dangerous as farming. It is difficult to predict where explosives may have been hidden by the Khmer Rouge, along with air bombs dropped during the Vietnam War.

"When [people] move around they will stick very strictly to paths that they know are safe," says Mr Pursey. "One of the big problems for families is controlling their children from playing in mine-infected areas or picking up the explosives."

Mr Sorn remembers well his fear for his five children.

"They used to play around the house, the fields, everywhere. Of course I was worried but they are kids, they want to play."

If an adult is injured, it can bring desperate hardship for the entire family.

"It's not just physical, they're also stigmatised," Mr Pursey says. "They find it very difficult to get married because they're not considered an economically viable partner, especially if it's a man because his breadwinning ability is hindered."

Mr Sorn's brother-in-law lost the bottom half of one leg to a mine while working in his field.

"He is still farming near here but his life has changed a lot," says Mr Sorn. "Even going to the toilet is very difficult [but] in Cambodia, if a father is injured by a landmine he will still try — there is no choice."

Tet Sorn has not been able to farm his 7 hectares of land until now. ( ABC News: Zoe Osborne )

Medical care in Cambodia is limited, particularly for the poor, and receiving treatment for a landmine injury can be very difficult.

Mr Sorn's family had to carry his brother-in-law out of his field in a hammock and onto a wooden cart to make the 60km journey to the provincial hospital.

Although there are now health centres in every commune, their quality is low and the price of medical care can make treatment impossible for Cambodia's vast rural poor. The Cambodian government has announced plans for a universal healthcare system, but this goal is a long way off.

CMAC de-miner holds an APOPO rat at the beginning of the day's work. ( ABC News: Zoe Osborne )

'It's like if you have a kid'

Efforts by NGOs and government mine action groups have brought accidents down from 1,573 in 1992 to just 42 in 2017.

While most of the mine clearance was achieved without rats, they offer a new option for clearing ground.

"Former conflict areas usually contain many metallic objects in the ground, so using a metal detector can take some time", says APOPO's Cambodian Program Manager MA, Michael Heiman. "APOPO rats are trained to indicate only the explosives, so work can be more efficient."

APOPO rats are bred from wild African giant pouched rats and trained in Tanzania.

Vendeline Shirima, (Mine Detection Rat Technical Adviser from Tanzania) with one of the APOPO rats. ( ABC News: Zoe Osborne )

"We choose rats because they are small ... so when they step on mines they don't easily explode," says Vendeline Shirima, Mine Detection Rat Technical Advisor. "It's also easier to house them, transportation is easier, food is cheaper..."

Rats have a highly developed sense of smell and are not as dependent on their handler as dogs, the animal more commonly used for mine clearance. They can work with anyone. But APOPO staff still share a strong bond with their animals.

"The handlers know the behaviour of their rats — it's like if you have a kid. Sometimes you can see he is not happy, you must identify why," says Mr Shirima.

Vendeline Shirima, (Mine Detection Rat Technical Advisor from Tanzania) with one of the APOPO rats. ( ABC News: Zoe Osborne )

With 1,640 square kilometres of potential minefields left to clear, a mine-free Cambodia remains a long way off, but the dream keeps Mr Theap and his colleagues going.

"Cambodians have been suffering for decades of war between Khmer and Khmer," Mr Theap says.

"It's time to love and help each other."