How dogs could prevent the spread of malaria

November 7, 2018

Several years ago, British entomologist Steve Lindsay landed at an American airport and was intrigued by the sniffer dogs searching for fruits and vegetables in the baggage claim area.

Seeing as studies have shown that malaria releases a signature scent, Lindsay, who studies malaria at Durham University in the UK, wondered if dogs could smell malaria in a person.

He set out to train canines to smell parasites living inside people.

As people hop off international flights, these watchdogs could take a few sniffs at each person’s skin and paw at the people who might be carrying a parasite.

“The person can be taken aside and possibly tested for the disease with a blood test,” Lindsay explains.

At a scientific conference on Monday, Lindsay presented preliminary evidence that dogs can detect whether a person is carrying the malaria parasite in their blood by just sniffing their odor – or more specifically, sniffing a small piece of their sock. The researchers trained the dogs by rewarding them with a snack when they correctly identified and sat next to a malaria-tainted sock.

The two trained dogs are Sally, a Labrador retriever, and Lexi, a golden retriever-Labrador mix. Despite the small sample size, the results were encouraging. Overall, Sally and Lexi had a success rate of about 70% for picking out the socks worn by people with malaria. Each dog correctly identified at least 21 of the 30 samples.

The dogs did better with the socks worn by people not infected. Each dog correctly identified at least 131 of the 145 negative samples, for a success rate of about 90%.

While larger studies are needed, the dogs’ performance isn’t too badcompared to some commercial tests. For example, one study found rapid diagnostic tests correctly detected malaria 60% to 90% of the time, depending on the particular conditions. And the tests correctly identified the negative samples about 90% of the time – which is similar to the dogs’ performance.

“We made it hard for the dogs,” Lindsay said.

“We didn’t have many samples to train them with – just 30 socks worn by people with malaria. ”

Lindsay hopes that trained dogs could, one day, work at ports of entry to help countries keep malaria from entering, especially in places that are trying to eliminate the parasite or have just gotten rid of it.

“At the moment, malaria detection relies on taking a person’s blood with a pinprick, but you can’t do that to everyone coming across a border. The malarial dogs would be a noninvasive method of picking up the parasite.”

There’s still quite a few studies to be done before sniffer dogs for parasites are a thing. For starters, the researchers don’t know whether the dogs can actually pick up the scent on a person’s skin in addition to their socks, or different species or strains of malaria found in various parts of the world, and whether the dogs are able to differentiate between a malaria infection and an infection caused by another pathogen.

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