In 2016 APOPO studied the accuracy of detection rats by comparing them with 1) the standard technology used in clinics (smear microscopy), 2) GeneXpert (very accurate but expensive) and 3) the gold-standard definitive culture (slow and expensive). This study found that the rats are significantly more sensitive than the smear microscopy used in clinics, that is, they are more likely to find TB-positive samples.
Volatile Organic Compounds (VOCs)
APOPO is continuing fundamental research into what the rats actually smell through collaboration with the Max Planck Institute and Braunschweig University. Detection rats make their decisions based on what VOCs have been paired with food in the past, but human sputum samples contain many other substances that emit VOCs in addition to the TB bacteria.
APOPO conducted research to evaluate the potential for detection rats to serve as the initial test for mass-screening activities of high-risk populations. For this study, 4,000 prisoners in Maputo and Morogoro were tested by the rats and by GeneXpert. In these populations, actual prevalence of TB is very low, ranging from 0.3% to 2%, as opposed to the 10% to 25% at TB clinics.
Generalization and indication times
Over the years, APOPO has developed and partially automated its “line cage” for training and deploying TB-detection rats. APOPO is also currently using this apparatus to investigate the basic variables that influence training success as well as explore alternative training paradigms. This research is conducted with well-defined scent samples commonly used in the fragrance industry, and is generously supported by the Firmenich Family.
Illicit wildlife detection
Pangolins are one of the most widely trafficked mammals in the world and African species are now facing possible extinction due to illegal trade. In late 2016, APOPO established a partnership with Endangered Wildlife Trust of South Africa to collaborate on a proof-of-principle experiment, funded by the US Fish and Wildlife Services, to examine the abilities of our African giant pouched rats to detect illegally trafficked pangolins and African hardwoods.