Kitten-sized
rats are being used by scientists to detect tuberculosis-causing bacteria in a
project which hopes to save both time and money
The Guardian, AFP, Tuesday 24 March 2015
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| A giant rat used to detect tuberculosis-causing bacteria at Apopo research centre in Eduardo Mondlane University in Maputo, Mozambique. Photograph: Adrien Barbier/AFP/Getty Images |
Giant rats
may strike fear and disgust into the hearts of homeowners worldwide, but
researchers in Mozambique are improbably turning some of them into heroes.
At Eduardo
Mondlane University in the capital Maputo, nine giant rats are busy at work –
sniffing out tuberculosis-causing bacteria from rows of sputum samples.
These are
no ordinary rats, as they have undergone six months of training in Tanzania.
Their most distinguishing asset is their impeccable sense of smell.
Placed
inside a glass cage, a rat darts from sample to sample, then stops or rubs its
legs, indicating that a sample is infected with a TB causing bacteria.
Once the
task is complete, it is given a treat through a syringe for a job well done.
“Within 30
minutes, the rat can test close to a hundred samples, which normally takes a
laboratory technician four days,” said Emilio Valverde, TB program director at
APOPO, the organisation leading the research.
The
project, which started in February 2013, has brought hope to thousands of TB
sufferers who sometimes receive false results and test negative using the
standard laboratory system.
In 2006,
tuberculosis was declared a national emergency in Mozambique, with 60,000
people in 2014 said to be infected, according to the ministry of health.
That number
was a 10 percent increase from 2013.
Samples
delivered to the university for testing are collected from 15 health centres
across Maputo.
Belgian
group APOPO is planning to expand the program to other parts of the country,
while working on getting the system approved by the World Health Organization.
The
organisation claims rat testing is more cost effective than other conventional
methods.
Each rat
costs around $6,700 to $8,000 to train, with a six-to-eight-year life span.
The cost is
lower compared to rapid diagnostic test GeneXpert, which costs up to $17,000
per device, setting the state back between $10 and $17 per test.
They are
light enough to cross terrain without triggering the mines, and are followed by
de-mining experts who reward the rats with bananas.
The rats
weigh up to 1.5 pounds and are said to be “easier to catch and train” –
according to Valverde.
Samples pointed
out by the rats to contain TB bacteria are then sent for further tests using
fluorescence microscopy, a more sensitive laboratory technique.
The results
are sent back to health centres, allowing patients to start treatment early.
Although TB
is a treatable disease, in underdeveloped countries like Mozambique it can be
deadly if left untreated and is particularly harmful to people living with HIV.
Mozambique
is one of the countries worst affected by TB and 1 in 10 adults is
HIV-positive.
With World
Tuberculosis Day being marked on Tuesday, the Mozambican Ministry of Health
said it was cautiously monitoring the APOPO work.
“This
technique has to be compared to others that are available and already WHO
approved, such as GeneXpert or LED microscope,” said Ivan Manhica, who heads
the national programme for tuberculosis at the health ministry.
According
to the WHO, TB killed 1.5 million people in 2013.
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