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Tanzania: Rats Sniff Out TB

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Project Stories

Rats Sniff Out TB

Trained sniffer rats could be the new weapon in the battle against the quickly rising number of tuberculosis (TB) patients that go undiagnosed each year in Africa.

Nineteen African pouched rats have been bred and trained in the past three years to detect and diagnose TB, with funding from a 2003 Development Marketplace grant. The unusual idea is being developed into what could be one of modern times most useful medical technologies by a group of Belgian and Tanzanian researchers and animal trainers.

The approach is very simple: rats sniff a series of holes, under which human sputum samples are lined up for evaluation and pinpoint the samples which contain TB bacteria.


Bart Weetjens of APOPO, a Belgian non-commercial agency that started its first research in early 1998, trained a couple of hundred rats to sniff and detect unexploded landmines. And then he realized the potential of using trained rats to solve disease epidemics.

An Apopo employee trains a rat to detect TB.

I was on a plane and heard in the news that the World Health Organization (WHO) made the announcement that this year, 2002, 2 million people died of TB, mostly in Africa. And they projected that by 2015 that number will increase to 8 million, Weetjens said. At this point it became clear to me that it was really worth trying to see if rats could detect TB, because the social benefit would be enormous."

With funds from the DM, APOPO built a research facility in Tanzania, which is linked to the Sokoine University of Agriculture and began pilot research and training of rats for TB detection. In partnership with the leading national TB programs, APOPO has since set up a sample collection program in six regional health centers that administer TB treatment. About 900 sputum samples are collected weekly, and used for comparative testing of the rats.

Rats are highly effective in diagnosing TB, Weetjens said. While a lab technician using a microscope can take a full day to analyze just 20 samples, a trained rat can go through several hundred in less time. APOPO's model of using trained rats to diagnose TB has been scientifically proven.

TB is treatable, but millions die of the disease because it goes undetected. One of the main reasons for the low detection rate is the lack of a cheap and reliable diagnostic tool that can handle big volumes of samples.

Sniffer rats may offer a solution. They have a highly developed sense of smell, are easy to tame, breed and train. Rats are also cheap, widespread, easily adaptable to different environments, and simple to maintain and transport.

Prior to deployment, the rats are trained to distinguish samples containing TB cultures from TB free samples. Their correct indications are rewarded with a food treat.

We are trying to develop a screening tool to massively screen vulnerable populations like refugee camps, slums and such, so that suspected cases can be immediately referred and treated in existing WHO structures, Weetjens said.

After winning a DM grant in 2003, APOPO received grants from Johnson and Johnson, a private trust, and more recently the National Institute of Health. The group employs 126 people, 15 of whom focus on the TB program.

There is plenty of possibility here, Weetjens said. Because the main priority in a country like Tanzania is health. 

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