Photograph — ADRIEN BARBIER/AFP/Getty Images

With about two billion people currently living with Tuberculosis worldwide, and the race to meet the target of a 20 percent reduction in TB cases by 2020, the world is in constant search of ways to effectively combat the disease with early and swift detection atop the list.

Following closely on the heels of the World Tuberculosis Day commemorated a little over a week ago, comes the news of a new and improved way to detect TB – rats, or super rats as some describe them. Giant African rats are being trained by a Belgian non-governmental organisation, APOPO, to quickly and easily detect TB.

The NGO is exploiting the intelligence plus the exceptional sense of smell possessed by rats to save lives. According to them, when rats are trained, their sensitivity for a specific scent increases. Not to mention their long life span and the low cost of maintenance.

The training process

At the age of four weeks, the rats are exposed to human interaction and to get accustomed to different stimuli. Then they are trained to differentiate scents and be rewarded with food at the sound of a click, this is described by the NGO as “click training and scent conditioning.” The next stage is that of multiple sample evaluation where they learn to evaluate large numbers of sputum samples.

The detection process

Suspected TB patients leave their sputum samples in the clinic. Checked samples are collected by the NGO, they get a set of positive and negative samples with the codes of correlating patients. The samples are inactivated to ensure that they are not contagious to the trainers and rats, after which they are presented to the rats for screening. They hover over positive samples for three seconds to let the scientist know the status of the sputum. One rat screens 100 samples in less than 20 minutes, a task that would take a lab technician about four days. To cap it all, a rat’s detection of TB is almost 100 percent accurate.

TB is the world’s leading cause of death from an infectious disease, killing more people each year than HIV and Malaria combined. The rat detection method of TB screening is, therefore, a huge leap in the health sector, particularly for heavily burdened developing countries. Currently, APOPO has trained 58 accredited rats and has 33 trained research staff. And with funding from the United States Agency for International Development, the NGO plans to train more rats and researchers. So far, mass screening for Tuberculosis is been conducted among prison inmates in Tanzania and Mozambique.


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