In Tanzania, Africa, rats are being trained by a Dutch Non Governmental Organisation (APOPO) to sniff out landmines, having already been used successfully in Mozambique for this purpose. Out of nearly 2,000 species in the order of rodents, the Giant African Pouched Rat (Cricetomys gambianus), is the favoured animal, as it is found everywhere in sub-Saharan Africa and is resilient to most tropical diseases. They are a cost effective and efficient way of undertaking what is otherwise a highly dangerous task for human operatives. The work is much less dangerous for rats as they are much lighter and therefore unlikely to trigger a mine. Training the rats to recognise the smell of TNT explosive takes around nine months and two rats can clear an area of 200 square metres (2,150 square feet) in two hours, whereas human mine clearers would need a day for the same area. Such rats have already cleared almost two million square metres of land in Mozambique. The rats can also be trained to detect tuberculosis in human sputum samples.