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Three animals that can detect diseases – News

You might be surprised to learn that you could share a home with a powerful disease-detecting agent.

When it comes to accurately diagnosing disease, you might think that you need expensive, high-tech machinery and equipment capable of observing what is happening in the body at great depth, but while these high-tech instruments are amazing, they are not the only instruments capable of detecting disease.

There are numerous cases of pet owners who unwittingly learned they had a health problem from their pet. Some examples include dogs licking, sniffing, and even trying to chew spots on their owner’s skin, spots that were later diagnosed as malignant melanoma.

In fact, many animal species – from the microscopic worm C. elegans to ants, mice and dogs – have successfully demonstrated the ability to detect diseases in people and biological samples during experiments.

The diseases detected are diverse: from cancer and urinary tract infections to Covid-19 and the gastrointestinal infection, Clostridium difficile.

Many of these diseases are potentially serious, especially in vulnerable and immunosuppressed patients, so early and accurate detection is essential.

These are just some of the amazing animals that can detect diseases in humans:

DOGS

Dogs are perhaps the best-known example of an animal capable of detecting a variety of diseases, including Parkinson’s disease, bladder cancer and malaria. Specially trained medical alert dogs can also detect epileptic seizures and low blood sugar levels in diabetic patients.

It seems that dogs’ impressive sense of smell is key to their ability to detect specific odours, even at incredibly low concentrations. In fact, dogs’ sense of smell is thought to be more than 10,000 times better than our own. They can even use their nostrils independently to investigate new scents.

Biodetection and medical alert dogs are initially trained to associate specific odors with a positive reward, such as a tasty treat or toy. They are then trained to recognize changes in odor or physical and behavioral changes in their handler that predict a seizure (or other health problem).

Biodetection dogs often freeze when they recognize a scent and wait for their reward. Medical alert dogs often interact with their handler, perhaps kicking or nudging them to signal that they need to take steps to protect themselves.

RATS

Rats are also excellent at detecting specific odors.

In Mozambique, the African giant rat has been trained to detect the scent of landmine explosives. These rats are also proving to be valuable medical detection partners, playing an important role in detecting tuberculosis in sputum samples recovered from suspected cases.

Rats are fast: it takes just 20 minutes to analyse 100 patient samples. They use their sniffing ability to detect the distinctive chemical signature of tuberculosis in the samples.

Payment for a job well done is a treat of avocado and banana. This makes these trained rats a valuable option in places where time and money may be limited for diagnostic and detection facilities. These rats have an incredible success rate, accurately detecting positive TB cases 81% of the time.

BEES

Even bees can detect signs of certain diseases in samples, including lung cancer, tuberculosis and Covid-19.

Bees are extremely sensitive to low concentration odors, allowing them to detect chemical changes in a similar way to dogs and rats.

Researchers have successfully trained bees to respond to the presence of specific odors by sticking out their tongues to receive a sugar reward. With training, this response becomes consistent and highly sensitive to odors associated with pathological states.

This ability makes bees useful for detecting diseases in the same way as other animals. Their size could make them an even more efficient and low-cost option for rapid sample analysis.

HIGHER SENSES

But how are animals able to identify the presence of specific diseases? This has to do with the ability of many animals to detect small changes in the chemical profile of a person’s scent.

Many species (including dogs, rats, and bees) can detect very subtle changes in substances called volatile organic compounds (VOCs) that the body releases at very low levels, even when healthy. In fact, exhaled human breath contains about 3,500 different VOCs. The composition and concentration of VOCs the body releases varies depending on a person’s health, and will be different if they are fighting an infection or dealing with a health problem.

The ability of animals to detect disease doesn’t just benefit humans. Not only can the C elegans worm detect cancer in human samples, but its superior olfactory sense means it can also detect cancer in samples from dogs and cats.

The ability of different species to accurately detect diseases could make trained detection animals an effective, noninvasive, fast and inexpensive way to detect certain diseases. It could even further enhance positive interactions between people and animals.

It is worth noting that due to regulations, animals used for disease detection are currently only considered detection “tools” that can be used in conjunction with medical diagnostic techniques. But if regulatory frameworks allow, detection animals could one day become a key component of diagnosis.

In fact, sniffing dogs were faster (and cheaper) at analyzing samples for COVID-19 than standard polymerase chain reaction (PCR) tests. By understanding the detection capabilities of animals, we may be able to help further improve laboratory diagnostic testing by applying some of their incredible skills.

While harnessing animals’ sniffing abilities can be useful to us, it is important to remember that the health and welfare of the animals involved must also be prioritised. The ethics of working animals must always be taken into account alongside considerations of the cost, safety and efficiency of any widespread disease detection programme involving them. – The Conversation

  • *Jacqueline Boyd is a Senior Lecturer in Animal Science at Nottingham Trent University.

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