Sniffing out tuberculosis in seconds

In APOPO's Tuberculosis (TB) lab, rats are also trained on a daily basis to detect the TB agent Mycobacterium Tuberculosis, in human sputum samples. New sputum samples are collected every week by APOPO from the DOTS (Directly Observed Treatment Strategy) centres, which are the "first point of care" clinics for TB in Dar Es Salaam, Tanzania. APOPO also receives the smear microscopy results from these samples, which identify the number of known TB positive samples "typically ranging between 10 and 25%" among the whole sample set.

The initial training stages for TB detection rats are similar to that of the mine detection rats. In a similar three-choice discrimination setup, correct indications of TB positive samples are reinforced with a food treat. From there, the rats work in a Line setup, where they evaluate a large batch of sputum samples for the presence of TB.

While this program is currently in a training and research phase, the rats frequently indicate and identify TB positive samples among the TB negative samples that came from the DOTS centres. These samples are returned to the laboratory for re-examination by microscopy, and a large number of them are confirmed as TB positive. These results are then returned to the DOTS clinics who recall the patients for further examination and treatment. In 2008, the TB detection rats increased the detection of the collaborating DOTS centres by approximately 30%.

Training and test results are carefully analyzed to determine the sensitivity and specificity of the rats, among other parameters. While in the research phase APOPO is providing a second line screen of TB sputum samples, however, the aim is to use the technology for first line screening and early TB detection in a proactive case-finding strategy.