How Rats Are Saving Human Lives With Their Noses

Forget the saying, ‘Like rats from a sinking ship.’ HeroRats are diving nose-first into danger zones and saving human lives as a result.
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You might not think there would ever be a good reason for combining the words ‘hero’ and ‘rats’ together, unless maybe you’re just an over-enthusiastic fan of Remy the rat’s cooking feats in Pixar’s Ratatouille.

One of APOPO’s future HeroRats in training. The rats are taught to only detect the scent of explosives, which helps eliminate the possibilities of false alarms that can slow down a human wielding a metal detector. Image Source: APOPO HeroRATS/Flickr

Since 1997, a non-profit organization headquartered in Tanzania and operating under the acronym APOPO (short for the mouthful of a Dutch name Anti-Persoonsmijnen Ontmijnende Product Ontwikkeling (or, as it is known by its English translation, Anti-Personnel Landmine Detection Product Development) has trained African giant pouched rats to detect two things that humans have the ability to but just not nearly as efficiently: landmines and tuberculosis.

APOPO’s founder, Bart Weetjens, is a Belgian-born hamster, mouse and rat aficionado who had been journeying across Africa as a student and witnessed firsthand the ongoing destruction and casualties in some of the most landmine-infested regions in the world. Estimates put the number of landmines buried across Africa at 37 million.

Over a dozen different landmine-clearing and awareness agencies are scattered across the continent, and according to the APOPO website over 60 countries “….are contaminated with hidden landmines and other explosive remnants of war.”

Why have landmines been a constant deadly thorn in the side of those who oppose their use? For one thing, it takes only one minute to plant/bury/hide 1,000 of them. They are inexpensive to produce — between $3 to $30.

In just one region of Africa, the Republic of Angola has over 70,000 amputees as a result of landmines being used within its borders, and over 8,000 of those amputees are children. Worldwide, it is estimated there are 110 million landmines currently buried in the ground right now, with that many produced and stockpiled but not yet placed. The cost to eliminate these deadly threats? Somewhere between $50-$100 billion.

Some of the landmines discovered by HeroRats. Explosive devices like those pictured above can still be found in almost 60 countries. Image: APOPO HeroRATS/Flickr

Tuberculosis (TB) is a much quieter threat, being airborne and contagious. Across the globe, TB is the deadliest infectious disease, claiming approximately 1.7 million lives annually. In sub-Saharan African countries, only half of those infected with TB are diagnosed and receive treatment.

Existing medical clinics are usually under-staffed, under-trained and lacking the proper funding to meet the diagnosis demands of entire regions. In turn, TB can quickly spread, with devastating social and economic results.

It takes nine months to train a HeroRat, but they can work in the field for years. Image: APOPO HeroRATS/Flickr

Looking into the feasibility of safely clearing areas of undetonated explosives (often referred to as “weapons of mass destruction in slow motion”) and upping the early detection rates of tuberculosis across Africa became a focus for Weetjens.

Initially, it started with trying to make the land safe to use for locals not wanting to become one of the estimated 8,605 victims landmines injure, maim or kill every year (according to the 2017 Landmine Monitor report). He found a study focused on gerbils being able to recognize the presence of explosives by their scent.

Armed with this discovery and his own experiences with various members of the rodent family, Weetjens sought out rodent expert Professor Ron Verhagen of the University of Antwerp. Verhagen recommended a lightweight, four-legged critter with the right nose for the job: the aforementioned African giant pouched rat.

These two-foot-long animals have several factors working for them when it comes to locating landmines and tuberculosis, despite having lousy eyesight. These include a canine-esque sense of smell that can detect as little as 28 grams (one ounce) of explosive material. They also have a long lifespan of 8 to 9 years, meaning they are well worth the $6,700 (in American dollars) cost of training one animal.

Humans can do the same job as a rat, but at a drastically slower pace due to metal detectors picking up constant false readings due in part to search areas already having shrapnel scattered everywhere from previously detonated mines. Image Source: APOPO HeroRATS/Flickr

Although they might have ‘giant’ in their name, one advantage these rats have over humans carrying mine detectors or their canine compatriots is their body mass. The average landmine will explode if there is 5 kilograms (11 pounds) of weight placed on it, but these rats usually weigh in at just under 1.5kg (3.5 pounds).

It turns out that most landmine producers (and placers) don’t like to waste their armaments on small wild animals who might happen to stumble into a minefield. It’s a design loophole that the APOPO HeroRATS are born to take advantage of.

Unlike bomb-sniffing dogs, HeroRats are not handler-loyal, which means a rat will work with anyone. The rat is harnessed and a lead attached that guides where the rat is needed to search. Image Source: APOPO HeroRATS/Flickr

So what does it take to become explosives or tuberculosis-sniffing rat? Almost 20 years into the program, litters of potential HeroRATS are bred from parents who are proven stars in the field. To prevent inbreeding and ensure genetic diversity, humanely trapped rats are occasionally introduced into the breeding pool. One litter can have upwards of five pups in it, and pups stay with their mother until they reach three weeks of age.

There are risks being on the frontlines, including skin cancer. HeroRats get their ears coated with sunscreen frequently wile detecting, and when they discover an explosive device they are rewarded with fresh fruit. Image Source: APOPO HeroRATS/Flickr

The first step in the training process involves socialization — handlers gently carry a pup so that it can become accustomed to interacting with humans. While this happens, different sounds and smells get introduced, and then the basics of positive-reinforcement training begin. Like canines, clickers are used to teach the pups to associate one sound with food.

That food is given as a reward for completing a task, which will eventually become sorting through environmental smells to pick out a target scent. In the case of potential mine-detecting rats (MDR), it’s TNT. For tuberculosis detectors of a litter (TBDR), it’s B-positive sputum samples.

Tuberculosis samples are placed for a rat to sniff. A simple scratch on the floor of the test area means a positive hit. Image Source: APOPO HeroRATS/Flickr

While technically the working conditions are not as dangerous, these rats also have APOPO-trained relatives working to save human lives in a laboratory setting, too, sniffing out tuberculosis in spit samples at an astonishing pace in areas like Tanzania and Mozambique.

A single TB-detecting rat can work through more samples in ten minutes than a lab technician can do in a day. Image Source: APOPO HeroRATS/Flickr

Not to mention they’re bright enough to know that if they’re going to be asked to do life-risking work like scratch at the dirt on top of an explosive when they find it they should at least be given a hunk of banana as a reward and a decent retirement package when they decide to hang up their harness.

They can also clear in 20 minutes an area that would take a team of their two-legged cohorts 25 hours to do, thanks to their laser-like focus on sniffing for explosive materials only; shrapnel or metallic scrap doesn’t set off false warnings to slow them down like it can a team armed with metal detectors.

The surroundings may be drastically different, but the overall concept is the same: find the bad stuff, get a yummy reward. Image Source: APOPO HeroRATS/Flickr

In total, the TNT-detecting skills of the APOPO HeroRATS have helped in finding over 105,000 landmines and the clearing of nearly 22 million square meters of land.

Now being used in other mine-laden countries like Cambodia (4930 landmines discovered and neutralized), Vietnam (four mobile teams have removed almost 19,000 mines and ordinances) and Thailand (662 landmines cleared and an additional 934 explosive devices neutralized) not one of APOPO’s 111 mine-detecting rats has been lost in the line of duty.

While technically the working conditions are not as dangerous, the APOPO-trained relatives of the MDR field workers are saving thousands of human lives in a laboratory setting, too, sniffing out tuberculosis in spit samples at an astonishing pace in areas like Tanzania and Mozambique. One TBDR can screen in 20 minutes the same number of samples as a lab technician would require four days to assess.

In Tanzania, the TB rats are now being used in 21 medical centers. During the initial stages of rats being involved with the TB screening process in Mozambique, they were responsible for a 44% increase in the detection of the disease.

Overall, TB clinics across Africa using HeroRATS have seen their detection rates jump by 40%. In total, 11,000 additional cases of tuberculosis have been diagnosed from over 400,000 samples screened.

Like their landmine-seeking brethren, the TB rats are trained to look for specific ‘red flags’; in the case of tuberculosis, it’s the scent of molecules associated with Mycobacterium tuberculosis. Considering TB kills more than 40 times as many people in Africa a year compared to landmines, the potential for HeroRATS to be a positive game changer in substantially lowering tuberculosis-related deaths is enormous.

However, HeroRATS are not yet endorsed by the World Health Organization (WHO) as stand-alone TB detectors, as efforts are still ongoing to improve their accuracy rates. One area where rats hold an advantage over traditional testing methods is evident when dealing with samples from HIV-positive patients. The HeroRATS ignore the presence of HIV in samples, which is something microscopy testing can not always do.

After life in the field, HeroRats get to lay back, relax and maybe even start a family. Image: APOPO HeroRATS/Flickr

According to APOPO, it’s not all work for HeroRATS. When not on the clock, the rats spend their day in ventilated interconnected cages and are often paired up with a sibling for company. All of the cages include clay pots with bedding, which mimic the rats’ natural underground sleeping arrangements.

There are also running wheels and toys, and every rat gets at least twenty minutes daily to play outside in an enclosed area. Rats get fed fresh fruit and vegetables, pet pellets, peanuts, sun-dried sardines and fresh water. They are also given extra vitamins and minerals to help boost their immune system and undergo health checks every week, performed by a university veterinarian.

APOPO HeroRats all enjoy a peaceful retirement after their active field duty is over. Want to help keep these rats comfy during their golden years? Consider contributing a monthly adoption donation to APOPO here.

Watch APOPO founder Bart Weetjens explain the HeroRats concept during a 2010 TED Talks presentation.

Watch: How Rats Are Saving Human Lives With Their Noses