Giant rats helping to sniff out TB

They have proven their worth in detecting landmines but Africa's giant pouched rats have a lesser-known but equally critical vocation - saving lives by speeding up tuberculosis detection.

It's all in the nose, says the Belgian non-governmental organisation APOPO. Its founders, in 1997, saw potential for these abundant rodents with a sense of smell as keen as a dog's but dismissed as pesty vermin -- or a potential meal.

"The biggest obstacle has been the negative perception that people have of the rat," said APOPO director Christophe Cox, whose NGO has been based in Morogoro in Tanzania's eastern highlands since 2000.

Yet 83,000 landmines have been neutralised in Africa and Asia thanks to the rodents, APOPO says, saving countless lives where explosives still maim and kill up to 20,000 people -- many of them children -- each year.

Eyebrows were raised when the group -- whose acronym stands for Anti-Personnel Landmines Detection Product Development -- branched out in 2007 to use rats for TB detection, under contracts with local authorities.

Today, more than 29 hospitals in Dar es Salaam and Morogoro send the Morogoro lab sputum samples. Another dozen clinics in the Mozambique capital Maputo send samples to an APOPO centre opened in that country in 2013.

The NGO says it has detected 10,000 missed TB cases, identified by workers like Oprah and Violet, whiskers bristling as they move along a row of test tubes.

"The big advantage is how quick the rats are. They can go through 100 samples in about 20 minutes, and this is what a lab technician will take four days to do," said Cox.

During TB detection, rats are presented with a mix of negative and positive samples, the latter decontaminated for safety "but the smell remains", said training director Haruni Ramadhan.

When a rat identifies a "true" positive, it is rewarded with a banana-peanut butter mixture. "We can only reward the rat if we are certain it is right," Ramadhan said.