Animals and Insects That Can Detect Cancer and Disease

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July 12, 2014 | 40,560 views

Story at-a-glance

  • Dogs have been used for decades to sniff out chemical vapors from bombs, find missing children, and more recently to detect malignancies, all through their powerful sense of smell. Other animals are now being tapped for similar purposes.
  • Fruit flies have a wide range of highly developed odorant receptors. Scientists using calcium imaging technology found that cancer compounds elicit a sensory response when placed on fruit fly antenna, even at low concentrations.
  • The giant African pouched rat’s keen sense of smell is now being tapped for landmine searches. Among the benefits: Rats are cheaper and easier to transport than dogs, and because they weigh less, they don’t trip the bombs upon discovery.
  • Extremely contagious, avian flu has devastated domestic poultry in Asia and the Middle East. Mice are now trained to detect avian flu-infected excrement of birds and poultry by smell, and can be taught to recognize other deadly pathogens as well.
  • Honeybees can be “conditioned” to pick up the scent of explosives. Their natural sensitivity can detect bomb residue even to a part-per-trillion ratio.
  • Artificial and biological robots are being developed as “electronic noses” for cancer and bomb detection, similar to that of extra-sensory animals. However, the natural ability of animals is still superior, at least for now.

By Dr. Becker

You already know that dogs have a sense of smell so powerful, law enforcement relies on them to sniff out drugs and explosives and track missing children. Domestic canines are also used to detect the presence of VOCs (volatile organic compounds) from all kinds of cancers and other diseases, sometimes before doctors have a clue.1

How do they do it? Scientists have determined that a dog's smell sense is at the very least 10,000 times more powerful than a human's.2 Dog noses have as many as 300 million olfactory receptors, while we only have about six million, and the area of their brains dedicated to odor evaluation is 40 times greater than ours.

But other creatures have proven just as adept in the nose category. Incredibly, the proboscis power many animals possess is racking up more than just a collection of interesting factoids; their scent perception is benefitting mankind in amazing and sometimes surprising ways.

Mouse Detectives

While dogs are useful in sniffing out malignancies in humans, mice, also, can detect illnesses in fellow creatures that threaten to devastate such industries as farming and beekeeping.

Avian flu3 is an extremely contagious disease that has stricken domestic poultry in some areas of Asia and the Middle East. To combat it, mice have been successfully trained, similarly to dogs, in how to differentiate between the excrement of birds and poultry infected by the disease. Scientists from the USDA explained how they rewarded mice with water each time they sniffed the feces of an avian flu-infected duck until eventually, the mice could distinguish which feces was contaminated.4

Researchers reported that mice are able to sniff out other pathogens, as well, which could be a significant breakthrough in ensuring quicker response time to potentially deadly virus outbreaks.

Get a Whiff of This: Fruit Flies Can Find More Than Fructose

Seemingly within moments of cutting into a watermelon, fruit flies can show up in your kitchen and wreak havoc. But science has found a way to turn this annoyance into a boon to the healthcare industry, using calcium imaging technology.

Because their metabolisms differ, cancerous and non-cancerous cells release distinctive volatile compounds, making it possible for malignant cells to be detected by scent. Insects, particularly fruit flies, have a wide range of highly developed and sensitive odorant receptors. With this in mind, scientists conducted tests and found that cancer odors elicit a response in fruit flies, even at low concentrations.5 In the trials, compounds applied directly to the fruit flies' antenna lit up with the increase of calcium, indicating cancer cells via a fluorescing sensor. Once again, the technology is transforming the way the medical community is improving cancer detection.

Rats to the Rescue

Experts estimate that as many as 80 million unexploded mines are buried in more than 60 countries.6 The Landmine Survivors Network in Washington, D.C., reports up to 50 people are killed every day around the world, many of them children, after stepping on explosives that sometimes have been hidden for years.

In Mozambique, torn by decades of civil war, authorities were concerned by the many land mines still lacing cities, countrysides and railways. In a quest to find a cost-effective way to detect these and other underground explosives, scientists at a Belgian company tapped into the highly sensitive smell sense of the giant African pouched rat.

Trained to detect the odor of TNT and other incendiaries, the one-and-a-half to three-pound rats are led on leashes by "handlers" and can cover 180 square yards in thirty minutes. Indicating buried explosives by scratching and biting at the ground, twenty rats once sniffed out nine unexploded mines along the heavily traveled Limpopo Railway in a single day.

A rat trained for this purpose costs around $2,000 – about $10,000 less than a dog with the same skills. Using rats to sniff out bombs not only discourages the use of canines for bomb detection, the rats are smaller and easier to transport and they're light enough to keep from tripping the explosive. They also have a natural resistance to tropical diseases.

Honeybees Are the Bomb… Squad

Dogs and mice aren't the only members of the animal kingdom scientists have trained to put the word out on possible perils. British scientists at Inscentinel Ltd. used the art of insect olfaction technology to teach honeybees to sniff out explosives. Amazingly, the training takes only minutes using "conditioning" methods. Bees, it turns out, have the sensitivity to sniff out bomb residue to a part-per-trillion ratio.

The initial study involved squads of 36 bees strapped to individual sensors. At the same time trace chemical vapors from explosives were released into the air, the bees were given food to encourage the automatic response of extending their proboscises to eat. That was an indication that bees could be trained to respond the same way when encountering explosive substances, scientists explained.7 In the field, when enough bees react simultaneously, an alarm sounds, alerting authorities.

Animals Show Robots How It's Done

Medical and law enforcement communities are already taking steps to use artificial and biological sensors in the development of similar "electronic noses" for cancer and bomb detection. Also called gas sensor arrays, the chemical analyzers are designed to search out cancer markers in a patient's breath and cell cultures, and perceive the presence of bomb-making materials.

Scientists say the ultimate goal is to get the robots' sniffing sensitivity to be as precise as an animal's, but while a hybrid of some variety may integrate nature and machine, they admit the natural scent-ology of animals is far superior to anything man-made. The up side is that at least an electronic sensor won't need to be fed.

[+]Sources and References [-]Sources and References

  • 1 Greenwood Veronique What Does Cancer Smell Like? Nov. 19, 2013
  • 2 Tyson Peter Dogs’ Dazzling Sense of Smell, Oct. 4, 2012
  • 3 Gao H Clinical Findings in 111 Cases of Influenza A (H7N9) Virus Infection, June 13, 2013
  • 4 Boyle Rebecca Dogs and Mice Could Be Trained as Roving Biosensors to Sniff Out Disease Before It Spreads, Study Says, Aug. 25, 2010
  • 5 Strauch Martin Lüdke Alje et al, More than apples and oranges – Detecting fruit flies with a fruit fly’s antenna, Jan. 6, 2014
  • 6 Mott Maryann Bees, Giant African Rats Used to Sniff Landmines, Feb. 10, 2004
  • 7 Inscentinel trains bees to detect bombs, June 11, 2007