Source: herorat.org
In East Africa trained rats are being used to find mines or detect tuberculosis. The HeroRATs, as they are called, are giant pouched rats that are trained by means of clickertraining.
The giant pouched rats (Cricetomys gambianus) are only very distant relatives of rats. They become up to 25-45 cm long and have a tail that is just as long as their bodies or even longer. They weigh 1 to 1.5 kg.
The idea comes from the Belgian Bart Weetjens, who had always had rats as a child. He thought of his rats when trying to find a solution for the global problem of landmines. He thought about how good the animals’ sense of smell is, how well rats can be tamed and how their slight weight can be an advantage in tracing mines.
He chose to work with the giant pouched rat. As this species is native to Africa it is accustomed to the African climate and it is resistant to the local diseases.

In training these rats a connection is first made between a click sound and food. Subsequently, tracking down a certain scent is connected to this click and food (a peanut or a piece of banana). Some of the rats are trained to detect mines and they work in the field. Others are trained in finding tuberculosis (TB) in samples of saliva. The rats are much faster in detecting mines and TB than humans are. This enables us to make areas of land mine-free sooner and to diagnose and treat humans with TB sooner.

For more information on HeroRATS or about the mother organisation APOPO see the links below.
Link to APOPO