Monday, February 21, 2022

Rats to the Rescue!

What has been able to save many lives by detecting land mines and explosives quickly and safely? The explosives-sniffing African giant pouched rat.

One in particular, named Magawa, was awarded the PDSA Gold Medal in September 2020 for bravery, an honor that acknowledges animals’ devotion to duty. Magawa was born in 2013 and died of old age in January 2022 at the age of 8. The rodent helped to clear more than 22.5 hectares (56 acres) of land in Cambodia between 2016 and 2021, detecting 71 land mines and 38 items of unexploded ordnance. The 1.2 kg (2.6 lb), 70 cm (28 in) long rat was trained by the Belgian NGO APOPO, based in Tanzania, that has been raising the animals, known as HeroRATs, to find land mines since the 1990s. The animals are trained for a year to detect a chemical compound in the explosives.

Although much larger than many other rat species, the giant pouched rat is still small and light enough to not trigger mines when it walks over them. Once it finds an explosive, it scratches the top of the ground to alert a human co-worker.

Man feeding a rat at APOPO in Tanzania (photo by Thukuk, Creative Commons Attribution-Share Alike 4.0 International license)

The non-profit  APOPO (Anti-Personnel Landmine Detection Product Development Organisation) trains giant pouched rats to detect not only land mines but also tuberculosis (TB). According to the organization, “innovative scent detection technology has a massive potential to relieve human suffering and promote development when deployed in the fight against tuberculosis and landmines, as well as other applications under development.” The rodents have been put to work in medical centers in Dar es Salaam, Tanzania, to discover the existence of TB in humans, and in the Mozambique capital of Maputo, to double-check 75% of potential TB samples from medical centers there. This method is particularly beneficial in low-income countries in Sub-Saharan Africa and South East Asia, where TB is most widespread and appropriate detection tests are in short supply.

One scientific article in The Behavior Analyst provides more information: “APOPO is exploring the use of African giant pouched rats (Cricetomys gambianus) to detect the presence of TB. These large and long-lived rats, which are native to much of Africa and have an excellent sense of smell, detect TB by sniffing sputum samples. They are trained to respond consistently in one way (pause) if the sample contains the TB bacillus (is positive) and respond in another way (not pause) if the sample does not contain the bacillus (i.e., is negative). Each rat can test hundreds of samples each day, allowing inexpensive testing.”

So using rats is much cheaper and faster than the usual technique employed to detect the disease in many developing countries, where lab technicians use microscopes to look at the sputum samples, or mucus, of potentially infected people to see if TB bacteria are present. This cost savings and increased speed is very good news because, according to the World Health Organization, TB is the “13th leading cause of death and the second leading infectious killer after COVID-19.” In one recent study, described in Medical News Today, “The standard [microscopy] tests detected TB in 34 [of 982 screened] children, but when the researchers used rats, a further 57 cases were found and confirmed. This amounts to almost 68 percent more cases.” Other research continues to collect the evidence needed to confirm the effectiveness of the technique using these rats. 

African giant pouched rats have a long tail with a white tip and white paws. Their body is covered with buff-gray fur, with underparts that are slightly paler. They have long, dark whiskers. These rats have cheek pouches they use to carry food back to their burrows, where they eat or store it.

Featured image: Cricetomys gambianus named Arthur (image by Louisvarley, Creative Commons Attribution-Share Alike 4.0 International license)

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