Laboratories in Kenya and Tanzania train rats to detect tuberculosis

In laboratories in Tanzania and Nairobi, rats have been trained to sniff out tuberculosis.

Already known for finding land mines, the rodents could now transform the way the disease is detected.

The African giant pouched rats work with scientists at the APOPO Project, a Belgian non-profit organisation in Tanzania, because they can detect the smell of the deadly disease.

A study conducted by APOPO in 2016 compared the accuracy of the rats to that of standard methods used in laboratories such as smear microscopy, bacteria culture tests and Genexpert - a rapid test for tuberculosis.

Joseph Soka, programme manager for TB at APOPO, said: "The sensitivity of these rats is as high as compared to microscopes and as compared to other tests, their sensitivity is independent of HIV status. 

"That is, they can easily identify tuberculosis in people living with HIV, keeping in mind that these people living with HIV, it is very difficult to be diagnosed by the standard test, including Genexpert in microscopes."

APOPO is already known for training rats to find landmines but training them to detect TB was new territory when they adopted the programme back in 2008.

Now the animals work in 21 medical centres in the Tanzanian capital Dar es Salaam as they are thought to be faster at detecting the illness than standard methods.

Many developing countries heavily rely on old TB detection techniques that entail the use of microscopes to examine the sputum of potentially infected patients. Dhaval Shah, veterinary pathologist at Pathologists Lancet Kenya, said rats can speed up the process. 

"So, the conventional laboratory techniques can take anywhere from two hours to even 14 days per sample, depending on what technique you use," he said. "While the rats will be able to complete testing of fifty samples within two hours and this would be ideal in far places or remote places like Mozambique or places in Mozambique which are rural."

According to the WHO, TB claimed the lives of 1.6 million people in 2021 including 187 000 people with HIV. The disease is the 13th leading cause of death globally and the second leading infectious killer after COVID-19.

The WHO estimates that in 2018, 162,000 people (551 cases per 100,000 people) contracted tuberculosis in Mozambique. The figures highlight the need for a speedy, reliable and affordable technique to detect the TB causing bacteria.

It is hoped the use of rats might do away with the need for time-consuming microscope testing.