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Rats, hated pests now life savers

BY EBELE ORAKPO
YOU see them everywhere! In homes, offices, market places, places of worship, on the streets, in the gutters, dumpsites, just name it, they are there live! They come in all shapes, sizes and colours. There are the locals and the expatriate variety popularly called Belgium rats which by the way, came into Nigeria ‘legitimately’ with all the travel documents complete, courtesy of the importers’ containers.

In Lagos, they are known as landlords or tenants depending on how daring they are. Some only come out to the sitting room when you have visitors, announcing their presence boldly.

Although all these may sound funny, but the fact is that they are dangerous as they have been reported to be reservoirs of the bacterium which causes Leptospirosis, a disease considered the most widespread disease that is transmitted by animals in the world.

Like Eneke the bird said in Prof. Chinua Achebe’s Things Fall Apart, since men have learned to shoot without missing, he has learned to fly without perching and so has the fierce battle between man and rats been as the rats are becoming wiser by the day and refusing to be caught by the various traps set by man to destroy them.

However, it is not all bad news.  Rats are useful after all, according to APOPO, a Belgian NGO with headquarters in Tanzania. This group researches, develops and disseminates detection rats technology for humanitarian purposes. This has once again proved that nothing in creation is totally useless. These researchers have found a means of putting the ‘bad guys’ to good work.

A report on the website of The Neu Afrika said in Tanzania, rats instead of being killed through traps and poisons, are fed, housed and trained to be able to sniff out land mines and tuberculosis and in so doing, lives are saved. These rats are called Hero Rats.

The report went on to say that rats were chosen because of their exceptional sense of smell as they can detect explosives if well trained. Comparing the use of Hero Rats to the use of metal detectors for the job, the report said: “Unlike metal detectors, they can detect both metal and plastic-cased landmines.

They save lives by detecting unexploded land mines which can then be handled safely. “Once fully trained, a Hero Rat can pinpoint the location of landmines quickly and effectively, or sniff out deadly tuberculosis (TB) faster than traditional laboratory microscopy.

Not only that, they work for peanuts! In short, Hero Rats provide a simple, innovative and cost-effective solution to some of the complex global problems facing humankind today. The rats can evaluate 40 sputum samples in just seven minutes, equal to what a skilled lab technician will do in a full day’s work.”

In the same vein, “two of APOPO’s mine detection rats, working with two human handlers, can cover 300 square meters of land in one hour while it will take two full days for two manual de-miners using metal detectors to cover same.”

Hero Rats are not only faster, they are also more accurate. In the area of tuberculosis diagnosis, the rats are very useful. The World Health Organisation has said that tuberculosis kills1.7 million people each year, with 9.4 million new cases a year. In Africa, over 50 per cent of cases go undetected. Once fully trained, a Hero  Rat can sniff out deadly tuberculosis (TB) faster than traditional laboratory microscopy.

In their 2010 annual report, the Head of Operations, APOPO, Mr. Håvard Bach said “APOPO has trained and internally accredited more than 150 rats for landmine detection.  “In Mozambique, APOPO has cleared more than twice the area of land in 2010 as the previous year and the aim is to clear between 1.5 and 2 million square meters of land in 2011.

Operational land release

APOPO is continuing to refine its operational land release methodology, which will likely result in the release of additional areas in Mozambique through a combination of non-technical and technical surveys.” It will be recalled that Mozambique is one of the 66 countries affected by mines and explosive remnants of war (ERW) after nearly 30 years of conflict that ended in 1992.

Reports Think Africa Press, an online magazine, “APOPO has managed to train rats to accurately identify the TB virus in human sputum samples and, after successful trials earlier this year, is set to take its cost-effective, virus-detecting rodents to Mozambique, a country with a high TB incidence of an estimated 431 cases per 100,000 people.”

The New York Times of January 3, 2011, reported that researchers have found a new way of testing for tuberculosis that is fast, cheap and widely available: large rats that can smell the bacteria in a sputum sample.” But while the Gambian rat is accepted as a diagnostic tool in Tanzania, “the medical community is still skeptical,” said a researcher.

Conventional method of diagnosing tuberculosis involves expensive and complicated laboratory tests which many people cannot afford. Recently, the World Health Organisation endorsed a new machine that can give accurate results in less than two hours.

But the machine costs $17,000, and each test requires a $17 cartridge which is way beyond the reach of many. Not only that, smear microscopy, the most commonly used detection method in developing countries, is not very sensitive unless there is a high concentration of the bacterium. The result is that between 60 and 80 per cent of positive cases go undiagnosed.

So the use of Hero Rats is a blessing as they are affordable, fast and accurate.

A Hero Rat, according to reports, “can smell the difference between tuberculosis bacilli and the myriad other germs that inhabit human phlegm.

Alan Poling, a professor of psychology at Western Michigan University and the lead author of one study on the rats said:“while the animals had been accepted as a reasonable diagnostic tool in Tanzania, “the medical community is still skeptical.”

In the December issue of The American Journal of Tropical Medicine and Hygiene, Dr. Poling and his colleagues report a test of the rats using samples that were confirmed by laboratory culture as either positive or negative.

“The animals’ sensitivity- that is, their ability to detect the presence of tuberculosis- ranged as high as 86.6 per cent, and their specificity, or ability to detect the absence of the germ, was over 93 per cent. In another test that compared the rats’ success to microscopy, the rats picked up 44 per cent more positive cases.

Enumerating the advantages of using Hero Rats over metal detectors and the microscope to detect landmines and tuberculosis, the report said that apart from the rats having an exceptional sense of smell, and can easily be trained to detect explosives, the animals “provide a low-tech solution to the landmine problem, especially in low-resource environments.

They are light-weight (approximately 1.5 kg or less) therefore, will not set off mines when they stand on them (it typically takes 5 kg to set off a pressure-activated landmine). Rats are very sociable and easy to train, and they don’t mind performing repetitive tasks in exchange for a reward!.

When a rat spends at least five seconds at a positive sample, it is rewarded with peanuts and bananas. Eventually, the rats learn that a longer sniff at a positive sample gets a reward, and that negative samples are unproductive and should be skipped over quickly.

“Rats are small and very cheap to feed, maintain, and transport. They are motivated by food, and are less emotionally tied to their handlers than dogs – it is therefore easier to transfer them between handlers.  Rats require little veterinary care, are resilient to many tropical diseases and are highly adaptable creatures.

African giant pouched rats have a long life span (6-8 years) which means a solid return on the initial training investment.”

According to APOPO’s annual report, in 2010 alone, 26,665 sputum samples were evaluated by Hero Rats, 12,347 patients second-line screened by Hero Rats, 716 tuberculosis patients detected only by rats. There was 43 per cent increase in case detection rate at partner hospitals and 7,160 new TB cases potentially prevented.


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