Our wonderful animals have done it again. This time the rat is helping to save millions of lives by detecting Tuberculosis in human saliva, using their remarkable scenting ability. A group of researchers at the Sokoine University of Agriculture in Tanzania have successfully trained African Pouched rats (Cricetomys gambianus) to detect and diagnose TB, using techniques first developed to teach the animals to find landmines.

These rats have a highly developed sense of smell and are easy to breed, tame, transport and maintain. They do not strike, down tools or demand salary increases and are very happy to work for peanuts!

Furthermore, they are found all over the African continent, adapt easily to new environments and appear to enjoy performing repetitive tasks. These little fellows weigh in at just over a kilo and, sporting mini harnesses, are already sniffing out deadly landmines across fields and roads in Mozambique, in an effort to clear the devices that still kill and maim people after past wars.

Another plus is that they are easily deployed in large numbers, due to their small size, light weight, and the fact that one trainer can work with many animals, whereas a dog-handler will usually work with only one, or at the most two, dogs.

Now please don’t think the dog is about to become redundant because that’s just not true. We all know our canines can be taught many amazing tasks over and above the traditional drug, explosive and substance detection … not forgetting their lesser-known skills, such as cancer detection in humans long before it’s diagnosed, finding underground gas leaks in frozen soil and locating corpses under water. And recently, not to be outdone by modern forensics, dogs are also using their finely tuned noses at Crime Investigation Scenes to detect semen, human blood and fire accelerants, to mention only a few of their endless talents.

But maybe the time has come for man’s best friend to roll over and make way for the lowly rodent which has emerged as a true professional and is hungry to succeed at sniffing out odours. These dainty, whisker twitching, African pouched rats are proving extremely accurate at diagnosing TB, as well as getting the job done in a fraction of the present time and cost. Furthermore, lab technicians, using a microscope, can analyse only 20 samples of saliva a day, whereas a trained rat can analyse about 120 to 150 samples in just 30 minutes.

“Millions of people worldwide suffer from TB,” says the project director, Bart Weetjens. “To them and their relatives, this discovery is very good news, and we have started to receive calls from all over the world.” Also according to Weetjens, both wild and laboratory-bred rats can be trained in about 4 to 6 months, and require minimum human skill.

So How Are Rats Trained To Achieve This Phenomenon?

Well, actually it’s really quite simple, as they are trained in much the same way as dolphins and most performing animals are - by using a Clicker. In essence, Clicker Training is a reward based, conditioning technique. A single click indicates a correct or desirable response, which is always followed by a food reward. Because favoured treats are used, the subject quickly learns the appropriate response required to earn a prize. The result is a keen candidate very willing to work for its supper, so to speak.

Now Picture This

A large, specially made, stainless-steel tray, with a number of shallow recesses in which marked specimens of saliva are hidden so only the scent permeates.

Now, enter the African pouched rat, who has probably been kept on short rations in order to make sure he works for his keep. With twitching nose and quivering whiskers, he hurries up and down busily sniffing each specimen as he tries to locate the scent which he knows will bring forth the peanuts or a squirt of banana pulp from a syringe. And then, “Yippee!”… the familiar bacteria odour to which he had been pre-conditioned and with which he associates treats.
Now he gets very excited and scratches at the hollow, indicating a positive hit, and is immediately rewarded with a yummy titbit - positive reinforcement at its best.

Now compared to our rats, even the smallest dog is cumbersome, subject to tropical diseases and takes 62 days to produce puppies. But our little heroes, on the other hand, gestate babies in only 27 days which gives them the edge on canines - so good or bad, there could never be a shortage of these African Giants because … er, they breed like rats!