Friday, November 2, 2018
A few years ago, British entomologist Steve Lindsay landed at an American airport and was immediately struck by all the furry creatures running around the baggage claim area.
"I was stunned to see sniffer dogs looking for fruit and vegetables," says Lindsay, who studies malaria at Durham University in the UK.
Recent studies have shown that people who carry malaria release a characteristic odor. "So I thought," If a dog can smell fruits and vegetables in their luggage, could they smell malaria in a person? "" Lindsay says.
So he set about creating the ultimate disease dogs – dogs that can smell living parasites Within People.
Then, as people descend from international flights, these watchdogs might sniff the skin and paw of those who may be carrying a parasite. "The person can be taken with a blood test and possibly examined for the disease," explains Lindsay.
Sound far fetched? Well, maybe it's not as far from reality as you think.
At a scientific conference on Monday, Lindsay provided preliminary evidence that dogs can tell if a person carries the malaria parasite in their blood by merely sensing their scent – or rather, sniffing a small piece of their sock. The researchers trained the dogs by rewarding them with a snack when they correctly identified them and sat next to a malaria-infested sock.
Lindsay and his colleagues trained two dogs – Sally the Labrador Retriever and Lexi, a hybrid of Golden Retriever and Labrador. Although the study was small, the results were encouraging. Overall, Sally and Lexi had a success rate of around 70 percent when they found out the socks worn by people with malaria. Each dog has identified at least 21 of the 30 samples correctly.
The dogs were better off with the socks worn by uninfected people. Each dog identified at least 131 of the 145 negative samples, which corresponds to a pass rate of about 90 percent.
Of course, larger studies are needed, says Lindsay. However, the performance of the dogs is not too shabby considering the performance of some commercial tests. For example, one study found that in rapid tests, malaria correctly detected malaria in 60 to 90 percent of cases, depending on the conditions. And the tests identified the negative samples about 90 percent of the time – which is similar to the performance of the dog.
And Sally and Lexi can improve, says Lindsay. "We made it hard for the dogs," he says. "We did not have many rehearsals to train them – just 30 socks worn by people with malaria."
Lindsay hopes that trained dogs could one day work in ports of entry to help countries prevent malaria from entering malaria, especially in places where the parasite is to be disposed of or has just been eliminated.
"Right now, detecting malaria depends on taking a person's blood off with a pinprick, but not everyone can reach that's reaching a limit," says Lindsay. "The malaria dogs would be a non-invasive method to ingest the parasite."
But there is still a lot to do before Sally and Lexi sniff at customs areas and baggage claims on their legs. First of all, the researchers do not know whether the dogs can pick up the smell on a person's skin in addition to their socks – and whether the dogs can distinguish between a malaria infection and an infection caused by another pathogen.
Finally, Lindsay and his team have not tested whether the dogs can detect various species or malaria strains in different parts of the world.
But if you think about it, the dogs do something remarkable, says Lindsay: They discover the presence of a microscopic organism that lives in the blood of a human or a liver just by sniffing at a sock.
Copyright 2018 NPR. More information can be found at http://www.npr.org/.
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