Giant Rats Can Detect Tuberculosis!

Rats aren’t all bad!

TB kills half a million people a year in Africa. That’s 1,5000 every day!

As a pest control company it is our business to keep on top of what pests are doing, no matter where they are in the world. AGPR (African Giant Pouched Rats) trained by the Belgian non-governmental organization APOPO are renowned for their ability to sniff out landmines. Due to their incredible sense of smell, they have developed a reputation for their skill and speed at detecting TB.

TB is the leading cause of death after HIV from an infectious disease. Over 9 million cases are recorded every year and the death toll hits around 2 million according to the World Health Organisation.

Poverty halts TB detection

People who are less fortunate, living in impoverished areas and those who dwell in prisons rarely show up for TB screenings due to lack of money and/or awareness. This creates a knock-on effect which in turn, creates a burden for health authorities that are actively trying to tackle the disease. Due to these services and facilities sometimes lacking speed, efficiency and accuracy when detecting TB, many cases go undiagnosed.

However, APOPO is tackling this issue, and with great success. APOPO is a social enterprise that researches, develops and implements detection rats technology for humanitarian purposes such as Mine Action and TB detection. Their headquarters is situated in Tanzania and they have operations covering Mozambique, Thailand, Angola and Cambodia.

APOPO, with the help of the USAID,hopes to recruit and train more rats to conduct prison screenings and offer aid to people who simply cannot afford to visit medical centres. Whilst this may seem like a last resort and an unconvincing medical practice, rats are not only faster than doctors at detecting the virus, but they are also better and far more reliable.

APOPO’s incredible rat-training program


The Process

From 4 weeks old, the rats are put through rigorous training exercises. The rats learn to recognise the presence of TB in samples of sputum, which is mucus that a patient coughs up from their lower airways. The rats are then rewarded with a treat if they succeed!

Every time they identify a positive sample, the trainers make a click sound, and a food reward of mashed banana or other fruit follows. The click-and-reward concept is introduced to the rats almost immediately, as this embeds the idea into their brains and remains there indefinitely.

“This is the instrument that communicates with the animal, the moment when the animals hears this sound, it has to stop what he is doing and come for food.”Mark Shukuru, APOPO

They then have to learn that sniffing in a hole will lead to the food reward.

“After the rat learns how put put their nose in the hole, then it will be easier when I present the sample in that hole. That’s how the rat learns the task!” – Shukuru

There are further stages to accustom the rats to the smell of the virus and to indicate when they have smelt it. Once this is done, the rats know that a whiff of TB results in a tasty treat.

The training at APOPO is highly effective. What would take a human scientist all day to diagnose, takes the rats 7 minutes! They’re also extremely accurate. People have actually asked for the rats to test them as opposed to medically trained scientists and doctors. Purely because the rats can genuinely sniff-out cases that doctors and scientists may easily miss.

So what makes a rat’s sense of small so superior to a human’s?

Whilst some humans are very good at identifying types of cheese (as an example) simply from their smell, rats sniff in stereo.

They can differentiate two very similar smells with just one sniff. About one in every one-hundred of a rat’s genes are given over to odour detection. Humans have to make do with one in every thousand. From a droplet of urine left by another rat, rats can determine gender, sexuality maturity and reproductive status.

Rats are also very clever animals and they’re easily trainable!

For the last three years, APOPO have been using rats in detection experiments for TB. The experiments have been met with roaring success, because on a weekly basis APOPO are able to pick up 10 patients that the hospitals would have otherwise missed or even misdiagnosed.

Is the process worth it?

The APOPO system is fast, cheap and has the potential to greatly lower screening costs in poor countries. While a doctor, scientist or lab technician may take a few days to detect TB in a patient, a trained rat can accurately determine 100 samples in 20 minutes. The cost of this process? 20 pence.

APOPO’s current program has screened more than 350,000 TB samples which has consequently eradicated 36,000 infections.

“Experiments show that these rats can detect a sample with TB parasites in a second and evidence has shown that they are able to sniff out even those with very minimal parasites.” – Khadija Abraham

In truth, rats are not only a more cost-effective way to detect TB, but they are more reliable. TB is usually detected by sputum smear microscopy, this is a slow and costly process that isn’t even that accurate. WHO insists that a lab technician should not test more than 20 patients a day, (due to fatigue) if they do, they risk a higher chance of misdiagnosis.

What do you make of all this? Would you prefer a rat diagnosing you if it was more accurate than a human?

Let me know in the comments below!



2 thoughts on “Giant Rats Can Detect Tuberculosis!”

  1. The APOPO system has been working very well in Cambodia and has the potential to do great things in Africa. This is an excellent article Alan, thank you for writing it.

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