Scientists at the Sokoine University of Agriculture in Morogoro in Tanzania trained rats to detect tuberculosis (TB) in human saliva by smell. They used the techniques first developed by a Belgian non-governmental organisation, APOPO, to teach giant rats to find landmines in Mozambique.
APOPO trains African giant pouched rats to sniff out explosives in land mines by conditioning them to associate the scent with rewards of food. The scientists in Tanzania exposed the (not giant) rats to the smell of the saliva of TB patients and associated the smell with reward of food.
The landmine-detecting rats weigh about as much as a small domestic cat. Their weight is light enough to allow them move over terrain without setting off the mines. The team of mine removal experts only expose the rats to the smell that they need to recognise and the team of mine removal experts follows them with metal detectors. The rats scratch at the ground when they smell a land mine to alert their human handlers to mines.
According to Alson Majanzota, a leader of one of APOPO’s rat handling teams. The rats are quick learners and “easy to work with,” He adds that they can check 200 square metres of land for mines in 30 minutes while a human with a metal detector could take up to three days to do the same job.
These rats do amazing jobs like super heroes in movies. While a laboratory technician, using a microscope, can analyse only 20 samples of saliva a day, a trained rat can analyse about 120 to 150 samples in just 30 minutes with accuracy, is this not amazing?
Easy Rat Training
According to the rat handlers, it requires little human skill to train them; the rats are quick learners and “easy to work with”. Both wild and laboratory-bred rats required four to six months of training to be able to detect TB bacteria successfully. While the giant rats undergo nine months of training, learning to sniff out explosives in old landmines buried underground.
Last year, APOPO received international funding of US$4.5 million from various donors and cleared 250 hectares of mined land in Mozambique. This year it is redeploying 78 rats to continue the work. Sokoine University of Agriculture has already sent 20 rats to Mozambique to help the country detect mines.
The university has already trained about 300 rats to detect landmines, but only a few are trained to detect TB bacteria. The World Bank grant will make it possible to train up to 400 rats for TB detection.
Cheap and Affordable Technique
Researchers and the rat handlers observed that the trained rats detect land mines and TB with speed and accuracy, that the use of trained rats to detect TB is a cheap and affordable technique, as the animals have a highly developed sense of smell, and are easy to tame and train, as well as to maintain and transport. Rats are found all over the African continent and adapt easily to new environments, and appear to enjoy performing repetitive tasks.
Landmine and Tuberculosis in Africa
Land mines kill and injure civilians and render lands impassable and unusable for decades. Many African countries have landmine problems. This is because warring parties used land mines during various internal and regional conflicts in these countries.
Top on the list of African countries with landmine problems are Egypt, Angola, Mozambique and Somalia. Tesfazghi Tewelde, manager of APOPO’s mine clearance programme in Mozambique, says land mines can still be found in an area the size of 1,400 football pitches in Mozambique.
Mozambique experienced 16 years of civil war between 1977 and 1992. Although the fighting has stopped, the tens of thousands of landmines left behind continue to claim lives. “Although the number of accidents drops as we get closer to the end, where there are landmines, the threat is real as people are still being killed or maimed,” Tewelde says.
According to the World Health Organisation, TB is a top infectious disease killer worldwide. Worldwide deaths from tuberculosis are expected to increase from 2 million this year to 8 million by 2015. Africa carries the most severe burden of new TB cases globally.
The close association between TB and HIV/AIDS has exacerbated the situation. There were estimated 1.2milion HIV positive new cases globally in 2014 about 74% of these people lived in Sub-Sahara Africa.
The director of the rat project in Tanzania, Bart Weetjens, points out that about 40 per cent of the 60,000 Tanzanians suffering from TB are HIV-positive and that detecting TB at an earlier stage raises the chance of securing effective treatment for both diseases.