The animal kingdom holds many surprises, but perhaps none as fascinating as its members' ability to detect diseases in humans. From ants and bees to dogs and rats, a range of creatures can sniff out illnesses with astonishing accuracy.

These animals use their keen senses to identify volatile organic compounds (VOCs) produced by diseases, offering a non-invasive, efficient means of early detection.

Ants: Tiny but Mighty Detectives

The silky ant, Formica fusca, commonly found across Europe, has been shown to detect breast cancer in urine.

Researchers at the University Sorbonne Paris Nord discovered that these ants could distinguish between the scent of urine from mice with human breast cancer tumors and that of healthy mice. This is due to their ability to perceive VOCs, which are chemicals produced in exhaled breath, sweat, urine, and blood that change when a person has a disease.

Baptiste Piqueret, a postdoctoral researcher at the Max Planck Institute for Chemical Ecology, expressed surprise at how quickly ants could be trained.

"In just ten minutes one ant can be trained," he told National Geographic.

 

Dogs: Man's Best Medical Friend

Dogs are perhaps the most well-known disease detectors. Their olfactory senses are estimated to be between 10,000 and 100,000 times more sensitive than humans'. Dogs can detect various cancers, including melanoma, breast, and lung cancer, with high accuracy. They are also capable of sensing other conditions like malaria and Parkinson’s disease, Treehugger reports.

In the U.S., dogs have even been used to screen people for COVID-19 at public events and schools.

Cynthia Otto from the University of Pennsylvania School of Veterinary Medicine highlighted the dogs' ability to detect chronic wasting disease in deer, which affects the brains of these animals and is usually only detectable through autopsy, according to National Geographic.

Medical Detection Dogs, a British charity, has trained dogs to detect a record 28 diseases. Treehugger reports.

Rats: Unlikely Heroes

The African giant pouched rat has been trained to detect landmines and tuberculosis (TB). In Mozambique, these rats have helped clear over 150,000 landmines since 2004. In Tanzania, which has high rates of TB, these rats have detected thousands of cases missed by local clinics.

According to APOPO’s head of training and innovation, Cindy Fast, who spoke to National Geographic, the rats can screen about a hundred samples in just 20 minutes.

In 2021, researchers in Korea found that trained rats could detect toluene, an odor-producing compound indicating lung cancer, with 82% accuracy. The rats communicated their findings by jumping onto a floating ledge when they detected toluene in human breath samples, Listverse reports.

Bees: Not Just for Honey

Honeybees have shown potential in detecting COVID-19. Dutch researchers trained bees to associate the virus's scent with a sugary reward.

Bees, like ants, can be trained in minutes and check a test in seconds, making them useful in remote areas where traditional testing is challenging. Their ability to detect diseases like tuberculosis and diabetes has also been demonstrated, Listverse reports.

Worms: Tiny but Effective

The nematode Caenorhabditis elegans, a tiny worm, has also been shown to detect cancer. Japanese researchers found that these worms could detect pancreatic cancer cells, while Italian studies showed they could recognize breast cancer cells.

The worms were drawn to cancerous samples in experiments, moving toward cancer cells and away from healthy ones, National Geographic reports.

Pigeons: Surprisingly Accurate

In a unique study, pigeons were trained to distinguish between cancerous and non-cancerous tissue images.

Despite their small brain size, they performed as well as humans in identifying cancerous cells in microscope images. Their ability to recall images and distinguish subtle differences makes them useful for validating future image-based cancer detection methods, Listverse reports.

Fruit Flies: Glowing Diagnosticians

Genetically modified fruit flies can detect cancerous cells. German and Italian researchers modified these flies to glow when they sensed cancerous cells, providing a clear visual indication. This unique method could enhance early cancer detection techniques.

Locusts: Brainy Bugs

Researchers at Michigan State University found that locusts could differentiate between healthy and cancerous cells. Electrodes attached to the locusts' brains detected the different gases produced by cancerous and healthy cells. This method could lead to innovative, non-invasive cancer detection tools, Listverse reports.

 

Humans: Smelling Superpowers

Joy Milne, a former nurse, noticed a change in her husband's scent years before he was diagnosed with Parkinson’s disease, The Conversation reports.

Clinical trials confirmed her ability to detect Parkinson’s-related molecules in sebum, a substance produced by the skin. This remarkable sense of smell could also pave the way for new diagnostic techniques. Animals’ ability to detect diseases offers a promising non-invasive diagnostic tool.

While more research is needed to understand the mechanisms behind their abilities, the potential for these natural diagnosticians in healthcare is vast. Their keen senses could revolutionize early detection and treatment, saving countless lives.