Detecting illness - Deploy insects!

Science is now using insects, worms and bees to detect diseases!

 Detecting illness - Deploy insects!

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• The story: Smell is a powerful sense. Dogs smell things at concentrations of one part in a trillion. Trained 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, before obvious symptoms appear. Researchers in Germany trained dogs to pick out saliva samples collected from those infected with SARS-CoV-2, from uninfected samples, with a success rate of 94%.
• Dogs versus insects: Training dogs takes time. Handlers must be paid. The animals themselves get tired and bored. Dogs are not a practical answer to the question of how to detect illness quickly, before it gets a grip. Fruit flies are better!

1. Tiny nematode worms called Caenorhabditis elegans may also be helpful
2. Unlike dogs, all are cheap and expendable, and their senses are just as good
3. They could provide economical, easy and non-invasive ways of detecting cancer, and also offer an alternative to laboratory tests for covid

• How far: Today, only four cancers — of the breast, cervix, colon and rectum, and sometimes the prostate — are screened for routinely, and only in places that can afford it. They account for only a quarter of the world’s cancer deaths. For many unscreened-for tumours, like cancers of the pancreas, stomach and oesophagus, early detection is vital. Animal-based diagnostics could extend the range of screening tests available.
• Fruit flies at work: Fruit flies smell things using their antennae, and researchers genetically modified the flies so that when they detect odiferous molecules, the resulting brain activity generates fluorescence under a microscope. The exact pattern depends on what the fly is smelling. With the help of machine learning, experts can recognise the patterns generated by odours from healthy cells and those generated by cancerous ones.

1. For experiments, researchers are using cancerous cells grown in a dish. Collecting such cells from people would require a biopsy. The ambition is to detect cancer in urine rather than cells.
2. Some are also keen to dispense with the flies, for looking at fly brains down a microscope is fiddly. Instead, they hope to find combinations of chemical-receptor proteins that can distinguish between urine from people with and without cancer. Those proteins could be integrated into sensors on silicon chips.

• Worms at work: Detection by worm relies on whole organisms, though the detection itself is automated. Researchers found that the worms tended to crawl towards urine from cancer patients and shy away from urine from the healthy. In new test centres, robots drop spots of urine onto the edges of Petri dishes, and then add clusters of worms at the centre. This process is repeated dozens of times per patient. If most of the worms crawl towards the urine, then the patient in question is likely to have one of 15 kinds of cancer.
• Bees at work: Detecting covid with bees involves a method that goes back to Ivan Pavlov and his dogs. The insects are offered sugar-water alongside SARS-CoV-2-infected saliva samples, but not with uninfected samples. They thus learn to extend their probosces when they sniff covid. One day, local apiarists may provide armies of bees for the training machines, just one of which can train more than 100 bees a day.
• Summary: Which of these ideas will come to fruition remains to be seen. Medical regulators will have to be convinced that what may seem wacky at first glance is actually sensible. Taking olfactory assistance from invertebrates might be the future of diagnostics!

 

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