African giant pouched rats trained by the Belgian non-governmental organisation APOPO are widely known for their work sniffing out landmines, and are now developing a reputation in east Africa for their skill and speed at detecting TB too.
APOPO, with funding from the United States Agency for International Development (USAID,) plans to recruit and train more rats to screen prison inmates.
Charlie Richter, APOPO’s US director, said: “We believe our unique TB Detection Rat technology will prove itself as an effective mass-screening tool.”
The rats undergo a rigorous training process that begins when they are four weeks old. As soon as the rats open their eyes, they are introduced to various stimuli and learn how to socialise and interact with people.
The rats learn to recognise the presence of TB in samples of sputum, mucus that is coughed up from the patient’s lower airways, and rewarded when they succeed.
The testing process starts when a rat is presented with a row of 10 sputum samples, and when it detects TB the rat hovers over the sample for 3 seconds, Richter said.
The rats’ accuracy at detecting TB is almost 100%, but they cannot distinguish between normal and drug-resistant strains, APOPO scientists say.
While a laboratory technician may take four days to detect tuberculosis, a trained rat can screen 100 samples in 20 minutes, and a rat screening can cost as little as 20 US cents when APOPO operations are running near capacity, he said.