Giant rats to the rescue, again

You've probably seen those African giant pouched rats used as landmine detectors before, and it turns out they are good at detecting disease too:

Rats are able to detect whether a child has tuberculosis (TB), and are much more successful at doing this than a commonly used basic microscopy test. These are the results of research led by Georgies Mgode of the Sokoine University of Agriculture in Tanzania.

The study, published by Springer Nature in Pediatric Research, shows that when trained rats were given children's sputum samples to sniff, the animals were able to pinpoint 68 percent more cases of TB infections than detected through a standard smear test. Inspiration for investigating the diagnosis of TB through smell came from anecdotal evidence that people suffering from the potentially fatal lung disease emit a specific odour. According to Mgode, current TB detection methods are far from perfect, especially in under-resourced countries in Sub-Saharan Africa and South East Asia where the disease is prevalent, and where a reasonably cheap smear test is commonly used. Problems with this type of test are that the accuracy varies depending on the quality of sputum sample used, and very young children are often unable to provide enough sputum to be analysed.

"As a result, many children with TB are not bacteriologically confirmed or even diagnosed, which then has major implications for their possible successful treatment," explains Mgode. "There is a need for new diagnostic tests to better detect TB in children, especially in low and middle-income countries."

Previous work pioneered in Tanzania and Mozambique focussed on training African giant pouched rats (Cricetomys ansorgei) to pick up the scent of molecules released by the TB-causing Mycobacterium tuberculosis bacterium in sputum. The training technique is similar to one used to teach rats to detect vapours released by landmine explosives. In the case of TB, when a rat highlights a possibly infected sample, it is analysed further using a WHO endorsed concentrated microscopy techniques to confirm a positive diagnosis.