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Freya, a springer spaniel, was trained in the detection of malaria parasites in sock samples taken from children in The Gambia.
Freya, a springer spaniel, was trained in the detection of malaria parasites in sock samples taken from children in The Gambia.
Photo: Durham University / Medical Detection Dogs / London School of Hygiene and Tropical Medicine
Freya, a springer spaniel, was trained in the detection of malaria parasites in sock samples taken from children in The Gambia.
Freya, a springer spaniel, was trained in the detection of malaria parasites in sock samples taken from children in The Gambia.
Photo: Durham University / Medical Detection Dogs / London School of Hygiene and Tropical Medicine
Steven Lindsay, a public health entomologist from Durham University in England, has been conducting research on malaria control for decades. His preferred approach, he says, is to "sit on the edge", giving off ideas that others could not.
It is perhaps not surprising that his latest project is inspired by the baggage claim area at Dulles International Airport. If the Beagles could use their noses to detect explosives or contraband in their suitcases, he wondered, could they also be trained to detect an incurable disease that kills more than 400,000 people each year?
Lindsay ended up addressing this issue as part of a project involving the dirty socks of hundreds of African children and a trio of sniffer dogs in England – and the answer clearly indicated yes. Dogs correctly identified socks worn by children infected with malaria in 70% of cases and those worn by uninfected children in 90% of cases.
"I think it's pretty extraordinary," said Lindsay, a senior scientist from a study presented Monday at the annual meeting of the American Society of Tropical Medicine and Hygiene. "We put these socks on African children for 12 hours, we remove them and freeze them for 15 months before we start training, and then the dogs can pick up that smell."
The project was funded by the Bill and Melinda Gates Foundation, which has launched a call for research on noninvasive malaria testing, in contrast to current tests that rely on blood samples. Lindsay and colleagues have focused on asymptomatic carriers, as they play a key role in the persistence of malaria, acting as hidden reservoirs. But finding them is a challenge because current methods make mass testing impractical.
Lindsay and her colleagues gave nylon socks to nearly 600 children tested for malaria in The Gambia, where the disease is endemic, and asked them to wear them overnight. The researchers ended up with 30 socks of asymptomatic malaria carriers and 145 socks of children whose screening test for the disease was negative. These were then wrapped in aluminum foil, frozen and sent to England, where they were stored at the London School of Hygiene and Tropical Medicine while a charity called Medical Detection Dogs formed the mutts.
Malaria modifies the volatile compounds that make up a person's odor, and previous research has shown that mosquitoes that spread the disease are more attracted to carriers, including asymptomatic ones.
"If a mosquito can do it," says Lindsay, "why not a dog?"
After all, dogs have proven their ability to detect cancer, narcotics, human remains and even killer whale feces. Jennifer Essler, a postdoctoral fellow who works with dogs who detect ovarian cancer at the Penn Vet Working Dog Center, points out what they feel when they detect an illness.
"We introduce them to the blood plasma," said Essler, referring to his own research. "Does that mean that they detect the body's response to cancer? Does cancer contain something in the blood? We're not really sure."
The Essler team is working with scientists at the Monell Chemical Senses Center in Philadelphia to discover what smells smell of ovarian cancer-sensing dogs. Indeed, the ultimate goal, she said, is not to have dogs tracked in dogs, but to take what dogs have learned to create an "electronic nose" that could detect ovarian cancer.
"For many reasons, you can not deploy dogs in many places," she said. In addition, "they are still beings, there are still days when they come in and have a bad day."
But malaria research provides another compelling example of dogs' potential, said Essler: "It's great that people recognize the capabilities of their dogs and how they can be used to help people."
Regarding malaria, Lindsay said he did not envision canine squadrons patrolling villages in sub-Saharan Africa. Electronic noses detecting malaria are also one of the possible outcomes of future research, he said. But in the shorter term, dogs detecting malaria could work at entry points in countries that have eliminated the disease and want to keep it.
There, dogs could identify porters before they arrive, Lindsay said. The training of sniffer dogs costs many thousands of dollars, he acknowledged, but "it is inexpensive compared to the cost of reintroducing malaria in your community".
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