Sniffer rats are used to sense land mines and tuberculosis in Tanzania and Mozambique

A baby rat in a small harness twitches its pointed nose incessantly, probing a field where it is being trained by a pioneering Dutch Non Governmental Organisation in Tanzania to sniff out deadly landmines. Other rats trained under the same scheme have already helped out clear large swathes of land in neighbouring mine-infested Mozambique.

The two-month-old baby rat walks unsteadily across the feeble patch followed by two trainers rolling a bar that teaches her to go back and forth across the patch in straight lines. With an acute sense of smell and easily motivated by food rewards, giant African pouched rats have been found to be highly efficient in mine detection by APOPO, the Dutch non-governmental
organisation that launched the training project - the first of its kind - in this Tanzanian town.

The rodents are trained to detect the TNT in landmines through behavioural psychology: a click sound to signal a food reward whenever they make the correct recognition. "Detection is the most difficult, risky and expensive part of mine action. Since rats are much easier to train than dogs, rats in this environment are much more apt," said Bart Weetjens, the founder of APOPO.

It takes two deminers a day to clear a 200 square-metre (2,150 square-feet) minefield, but if they work with two rats they can sweep up it in two hours. "They are very efficient. We have very high victory rates. So far they have helped re-open almost two million square metres of land" in Mozambique, said Bart Weetjens. Other rats in the same project undergo a different type of exercise - they learn to sniff out tuberculosis in laboratory sputum samples, providing a second-line of showing for hospitals in Tanzania where lab testing has 60 percent accuracy.

Training begins at four weeks old when the baby rats are out in the open to humans to rid them of their fear of people and new surroundings, after which they are taught to associate a click sound with food. Once that is achieved, they are then trained to differentiate TNT scent from other smells. When they successfully differentiate it, the click is sounded and they are given a bit of banana, thus reinforcing the link between positive TNT recognition and food.

In all, it takes nine months of painstaking on- and off-field training for a rat to be organized for mine detection