The Economist July 31st 2021 pp67|Science & technology|Screening for disease| “The nose knows” “Flies, worms and bees offer a novel approach to detecting illness”
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c. elegans from Leica-microsystems.com
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We all know that the sense of smell is a towering-strength for a dog. But we probably didn't realize just how effective they are being able to detect even a drop of scent in an Olympic-size swimming pool. Dogs can “sniff out explosives, and drugs, track missing people, and even guide truffle-hunters to their prizes. They can also detect illnesses, including cancer, malaria, Parkinson’s disease and covid-19” reportedly with high success like 94% for covid-19 and 97% for blood specimens taken from lung cancer patients. But dogs are about a coin-toss in training, half make it, half don't. Dogs also easily lose focus getting readily bored of the task at hand. Also, as a disease detection model, dogs aren't really very practical or scalable.
So enter other less familiar options from the animal kingdom like fruit flies, bees and nematode worms. Studying these simpler systems will more likely lead to laboratory-type devices for detecting disease by using their foundational molecular or cellular systems.
Studies by Giovanni Galizia (University of Konstanz) have achieved proof of concept using fruit flies for disease detection. Now Dr. Galizia is delving deeper by searching to “find combinations of [the functionally sensitive and selective] chemical-receptor proteins that can distinguish between urine from people with and without cancer. Those proteins could [then] be integrated into sensors on silicon chips.”
Using nematode worms Hirotsu Takaaki (Kyushu University-Japan) found that in a petri dish “worms (c. elegans) tended to crawl toward urine from cancer patients and shy away from urine from the healthy.” The process and analysis has been automated and Takaaki and team are genetically modifying the worms to further increase their effectiveness in cancer detection. They hope to “offer a test specific to pancreatic cancer next year.” Pancreatic cancer is not typically screened today but early detection for this and certain other cancers is key to increasing survival from the disease.
Image from Leica-micosystems.com
Whether these approaches will become mainstream is unclear but “having a little olfactory assistance from invertebrates might be no bad thing.”