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Mine Heir

Indigenous African rats prove adept at sniffing out trouble for people.

Today in Mice recently sounded the alarm about calls by researchers to move beyond the mouse model of studying human disease and begin using vast databases of human health information — or larger animals like pigs and dogs — in our quest to cure the ailments that afflict us.

But before anyone grows too distraught over the prospect of out-of-work rodents (or bloggers), consider this: a Belgian organization is using rats to alleviate two of Africa's greatest scourges: land mines and tuberculosis.

Antwerp-based APOPO has trained African giant pouched rats to use their highly developed sense of smell - which they employ in the wild to find their way back to food they've stored in their subterranean burrows -to detect land mines. The rats are sniffing in Mozambique, where mines are the deadly legacy of the country's war for independence and civil strife.

In addition to its olfactory prowess, Cricetomys gambianus also offers the advantage of being indigenous and therefore resistant to tropical diseases. Their relative heft (up to 3.3 pounds) makes it easy for handlers to keep an eye on them in the field, but they are still light enough not to trip the explosives they are searching for. Rats can be trained more quickly and cheaply than mine-detecting dogs, are easier to transport, and can be interchanged more readily among human handlers.

APOPO very diplomatically refrains from suggesting that rats will supplant dogs in the mine-detection business, noting that mine-detecting rats and dogs "are complementary tools within the mine action technology toolbox." The European Union for Humanitarian Demining has suggested that the best use of rats in mine detection may in fact be in the lab (where they sniff for explosive residue in air and soil samples from suspected minefields), due to the rodents' small size and inability to learn commands limiting their effectiveness in the field.

But there might be other job prospects available for rats looking for work.

Hypothesizing that TB bacteria emit signature chemical markers in the same way explosives do, APOPO decided to try training rats to sniff out the TB bacterium in human sputum samples, in an effort to combat Tanzania's growing TB problem.

The laboratory technique for diagnosing TB cases (microscopic examination of dye-stained biological material spread on a glass slide) has changed little in more than a century, and it's relatively slow and costly, and not especially accurate. According to an APOPO research brief, "Tanzania's chances of success to fight TB in the future depend very much on its capacity to detect TB cases quickly and correctly."

According to APOPO, preliminary results have "shown that trained rodents are potentially more reliable ... faster, and more cost-effective in detecting TB infected sputum than the standard smear microscopic test." (Lest anyone smell a, ahem, rat, APOPO has partnered with universities and government institutes to validate its results.)

Mine detection, of course, is hazardous duty - one job that humans probably wouldn't mind having outsourced to a rat. No word yet on how lab technicians feel about being nosed out of their jobs by rodents. But as long as APOPO doesn't start training the rats how to sniff out a story, we're all for this latest advance in "vapor detection technology."