(CNN) -- Niko Mushi hated rats, as did most people in his village near Tanzania's Mt. Kilimanjaro -- until he learned the critters had a nose for land mines.

Mushi, 32, has been working with giant African pouched rats for almost seven years. He now enjoys their company -- "They're just like my friend," he says -- but he concedes he was skeptical when the man who conceived the idea for HeroRats first told him they could sniff out live ordnance.

"I thought maybe he was making some jokes," Mushi said. "I was amazed that rats could do such a thing."

Before he started working with rats, Mushi had a comfortable job teaching the Kiswahili language at a Lutheran seminary. He was terrified when he first took one of his long-tailed protégés into a Mozambican minefield.

He'd heard stories of accidents involving the mines, mostly leftovers from Mozambique's civil war, which ended in 1992. He was not emboldened by the skeletons of soldiers and others who'd taken unfortunate steps before him.

But his rat found 16 land mines that day.

"We are not a good friend to these creatures," Mushi said of his countrymen, "but after people see this work that we are doing, they change this position."

Bart Weetjens is the brain and Buddhist monk behind APOPO (a Dutch acronym meaning Anti-Personnel Land Mines Detection Product Development), which trains HeroRats. He said Mushi's initial repulsion is common.

Prejudice against rats is "deep in our psyche" and has roots in the Middle Ages when the rodents were blamed for the plague, Weetjens said. He quickly cited Black Death's rightful culprit: fleas.

The Belgian-born Weetjens, 43, is an apt candidate to change rats' unsavory image. A self-professed rodent lover, he was given his first hamster, Goldy, for his ninth birthday.

"Fascinated as I was by it, I wanted to have a female hamster. Soon, I had a nest of hamsters," he said. "Mother didn't like that too much, so I took them to the pet shop and they gave me money for those hamsters."

He soon found out pet shops paid even more for rats, and more still for gerbils and squirrels. It wasn't long before Weetjens had a "kind of breeding arrangement in my room" and was selling various rodents for walking-around money.

At 14, he gave up his enterprise when he was sent to boarding school, but he maintained his love for rodents.

Several of Weetjens' family members had worked in Africa, and Weetjens harbored a commitment to the continent. In the spring of 1995, he was analyzing the world's land mine epidemic -- a cause made vogue at the time by Britain's Princess Diana -- when he came across research that spoke to his childhood proclivity.

Scientists were studying the use of gerbils in land mine detection, but they were using a system involving brain electrodes that Weetjens found unsustainable. He wanted a locally based solution that might empower communities.

"Yes, rats can do that," he thought. "I knew I was right, even if it was very hard to defend."

See APOPO videos of the rodents at work

It's difficult to quantify the scourge of land mines in Africa. Experts are reluctant to give statistics, but it's safe to say there are single countries hosting millions of them.

The International Campaign to Ban Landmines says land mines and related devices were responsible for 73,576 casualties worldwide from 1999 to 2009. Campaign data from 2007 say there were 5,426 recorded casualties, with almost a fifth of them in 24 African countries.

Death and injury, however, are only two ramifications of the buried terrors, said land mine expert Havard Bach, formerly of the Geneva International Center for Humanitarian Demining.

Unexploded ordnance renders roads, highways and enormous swaths of land useless, Bach said. Fear lingers for years after a single accident, holding back growth, movement, development and opportunities for commerce and aid.

"One mine in an area is enough to prevent an entire population from making use of it," he said.

In a land where resources are scarce, Weetjens felt rats were suited to the task -- but he had to get past people laughing at his plan. Bach said he kept an open mind.

"I just thought it was a strange idea," Bach said. "You come across a lot of silly ideas that never result in anything when you work in this industry."

Upon study, the rats' advantages emerged.

Their olfactory senses are superb. They're native to Africa, so tropical disease is no problem, and they don't grow heavier than the 3 to 10 kilograms required to trip a mine, Bach said. It also helps that the mine-sniffing rats are not bonded to individual trainers or prone to ennui, as dogs are, he said.

"If you compare them to canine mine detectors, it's pretty much the same in terms of sensitivity and capability," Bach said, noting that dogs are better equipped to work in brush or high grass that might conceal a rat.

"Rats are not going to oust dogs in this industry, but it's a very positive complement," he added. "You could say they work for peanuts."

Indeed, said Weetjens, cost is especially an advantage in Africa. It takes limited skill and only six to eight months to train a rat -- or a year for the "slow" rats because "some rats are smarter than others," said trainer Mushi, who oversees 14 rats.

The cost to train a rat is 6,000 euros ($7,700), roughly a third of what it costs to train a dog. Where dogs need expansive kennel facilities and regular veterinary care because of African climates, APOPO's kennel facilities at Sokoine University of Agriculture in Morogoro, Tanzania, can house up to 300 rats. The rats see a single vet once a week and are much easier to transport than dogs, Weetjens said.

Training begins with socialization when the rats are 4 weeks old because "it's really important they learn man are friends," Weetjens said.

A system of "operant conditioning" follows. Trainers teach the rodents to associate a clicking noise with something tasty: a banana or peanuts. The same treats are used to teach them how to signal when they find a mine and how to detect the scent of TNT in tea balls.

The final phase before they're shipped to Mozambique for accreditation includes several trial runs in APOPO's training minefields, some of which contain tea balls, others live mines.

Nailing down the regimen was tricky. At one point in APOPO's early days, the rats performed perfectly in trials, making Weetjens suspicious. It turned out the rats were outsmarting the humans.

"They knew which samples had been touched by the trainers," he said. "We have to remain extremely vigilant not to bring in additional cues that help the animal find out what the rewarding samples are."

It hasn't been easy convincing the international community that mine-sniffing rats are viable, but donors are coming around. A partners list once consisting solely of Antwerp University and the Belgian government now includes about 30 groups, including the U.N. Development Program, World Bank Development Marketplace and the Schwab Foundation for Social Entrepreneurship.

APOPO also enjoys sponsorship from individuals through its Adopt-A-Rat program.

Learn more about adopting rats

In June, Bach left his position of 11 years at the Geneva International Center for Humanitarian Demining, another partner, to become APOPO's chief of mine action and human security. He said it's "rewarding to work for a small firm with great potential."

In 2008 and 2009, about 30 state-accredited HeroRats, their noses atwitter, scampered across more than a million square meters of Mozambican land, ferreting out almost 400 mines and other ordnance. The U.N. says 9.6 million square meters still needed to be cleared in 2009.

Bach said APOPO is considering taking its rats to other war-torn nations, such as Angola and eastern Congo. Also, HeroRats' sniffers are being employed to detect tuberculosis, and APOPO is working to apply its techniques to pinpoint gas leaks, narcotics, tainted food and people trapped in rubble.

Though APOPO says its methods are being refined and the time it takes to train the rats is diminishing, Mushi said even after seven years he remains anxious walking into minefields.

"When people tell you that mine is live, you are very scared," he said, but he welcomes the fright. "Fear keeps you to be very, very careful, makes you cautious in every step that you make."