The diagnosis of pediatric tuberculosis (TB) is challenging in itself but especially so in resource-limited areas. A relatively inexpensive smear test is commonly used, but the accuracy varies depending on the quality of sputum sample supplied, and very young children are often unable to provide enough sputum to be analyzed.

As a result, many children with TB are not bacteriologically confirmed or even diagnosed, which points to the need for new diagnostic tests to better detect the disease in children, particularly in low and middle-income countries.

Enter the African giant pouched rat (Cricetomys ansorgei) as the clinician’s new diagnostic detective.

Anecdotal evidence indicates that people suffering from TB emit a specific odor. Past research conducted in Tanzania and Mozambique focused on training African giant pouched rats to pick up the scent of molecules released by the TB-causing Mycobacterium tuberculosis bacterium in sputum. This inspired researchers from Sokoine University of Agriculture, Tanzania, to pursue this rodent-based disease detection approach.

How does one train an African giant pouched rat? The training technique is similar to that used to teach rats to detect vapors released by landmine explosives. In the case of TB, when a rat highlights a possibly infected sample, it is analyzed further using a WHO endorsed concentrated microscopy technique to confirm a positive diagnosis.

Sputum samples were obtained from 982 children under the age of five who had already been tested using a microscopy test at clinics in Dar es Salaam, Tanzania. Smear tests indicated that 34 children had contracted TB. When the same samples were placed out for the rats to examine, an additional 57 cases were detected and then confirmed after being examined under a more advanced light-emitting diode fluorescence microscope.

The rats were able to pinpoint 68 percent more cases of TB infections than detected through a standard smear test.

The study was published in Pediatric Research.