A man lies unmoving, slumped in the rubble of a simulated earthquake, as an unlikely rescuer approaches: a rat with a backpack.

Whiskers waving, the rat breezes past garbage, toppled furniture and scattered clothes to find him and pull a trigger on its pack, alerting searchers above.

Then a resounding click. A survivor has been found. The search in Morogoro in Tanzania’s Uluguru Mountains is over and the rat scurries out of the abandoned building to be rewarded with a banana.

A successful mission is complete for this African giant pouched rat being trained for search and rescue operations.

"They are small and so they can penetrate rubble which is something that search and rescue dogs cannot do," said Fabrizio Dell’Anna, an animal behaviorist at APOPO, a Tanzania-based nongovernmental organization that trains the rats for lifesaving applications.

"So they can only smell from the surface of the debris. And they can carry a small backpack and that allows the operators that are outside the debris to communicate with the victim

From detecting land mines to sniffing out tuberculosis, these “hero rats” have become unlikely, and sometimes unrecognized, front line responders in Tanzania and beyond.

For decades APOPO has trained these rats, which have one of the most sensitive noses in the animal kingdom.

Since 2003, the rats have been finding land mines and, more recently, have been turned on to trafficked wildlife and earthquake survivors.

The rats begin training shortly after birth for specific missions and, with a longer-than-average rodent life span of almost a decade, can spend years carrying out their work. The cost of training each rat runs around 6,000 euros.

While the rats focused on explosives or survivors buried in rubble get all the glory, it is a group of rats inside a lab that are arguably the most impactful lifesavers.

These are not typical lab rats, but rather, as their proponents would argue, one of the world’s most effective detectors of tuberculosis.

Tuberculosis is an ancient respiratory disease that continues to run rampant despite centuries of research and treatment.

The World Health Organization said last October in its most recent TB report that the disease had resurged as the top infectious disease killer, with 1.25 million deaths and a record 8.2 million infections in 2023.

In sub-Saharan Africa, only about half of TB patients receive a diagnosis, according to a study by researchers in the UK and Gambia published in the National Library of Medicine, and this leaves them liable to spread the disease. Tanzania struggles with one of the highest global TB burdens, according to the WHO.

APOPO expanded into TB detection in 2007 and its rats have been deployed in Tanzania, Ethiopia and Mozambique.

The group works with 80 hospitals in Tanzania, collecting samples daily and bringing them to the lab rats.

"They have been collecting samples that our laboratories missed to detect tuberculosis," said Felista Stanesloaus, a doctor at a TB clinic in Morogoro

"Some of those samples are found to be positive, meaning there are people who have a problem that we did not detect. So, the rats help us to increase detectability of tuberculosis."

False negatives remain a persistent issue in TB detection and suppression because each infected person can spread the disease to 10 to 15 more people each year.

With their sensitive noses, the rats sniff out samples of sputum from patients, looking for positive TB cases that had been marked as negative.

Research suggests the rats are picking up on six unique volatile organic compounds in positive TB samples, said Cox.

The more existential challenge for these “hero rats'” comes from regulators and a wider health community who doubt this unconventional method of disease detection.

APOPO’s rats are not classified as primary diagnostic tools by the WHO. Instead, they are a second line of defense.