Malaria-Sniffing Dogs May Be the Key to Early, Life-Saving Detection

Some very good boys are training to save lives by doing what they do best: sniffing socks. It sounds weird, but it could be a medical breakthrough.

Malaria, a disease caused by a parasite that commonly infects human-biting mosquitos, annually sickens an estimated 300 to 600 million people. It can be fatal, especially if the patient is a child. According to the United Nations International Children’s Emergency Fund, malaria kills one child every 30 seconds. Fortunately, new research released Monday shows that the key to identifying people with the disease for treatment very well rest with man’s best friend.

At the annual meeting of the American Society of Tropical Medicine and Hygiene in New Orleans, a team of researchers presented a new proof-of-concept study demonstrating the disease-detecting power of dogs. Dogs are already used to diagnose some types of infections and maybe even cancer, as well as detect seizures and low blood sugar. Now, it appears that dogs can be trained to identify people infected with malaria, simply by sniffing their socks.

After four months of training, dogs were presented with socks that belonged to malaria-infected and uninfected children from Gambia. Researchers froze the samples for several months while the dogs were being trained. Despite this span of time, the dogs correctly identified 70 percent of the infected children and 90 percent of the uninfected children. When the dogs thought they detected malaria, they froze in place — just like they’d been trained to do.

The socks used in the study came from children with malaria who had not yet developed fevers. The team, which consists of experts from the London School of Hygiene & Tropical Medicine, the Medical Research Council Unit The Gambia, and the charity Medical Detection Dogs, hopes that in the future dogs can help identify which individuals are developing malaria before their symptoms worsen. As of now, the only way to identify and treat “asymptomatic carriers,” who can still cause new infections by passing along their malaria parasites to the local mosquito population, is to test or treat the whole community. Ideally, putting malaria detection dogs to work will significantly increase early malaria detection and help avoid unnecessarily medicating people who aren’t infected.

These good boys’ knack for disease detection comes down to their sense of smell. Lieutenant Colonel Eileen Jenkins, an active duty US Army veterinarian who has studied dog olfaction, tells Inverse that dogs have several unique features that allow them to smell better than we do — their sense of smell is about 10,000 to 100,000 times that of humans.

“The anatomy of the dog nose creates very efficient airflow and allows dogs to use each nostril independently, which helps them locate odor sources well,” Jenkins explains. “When smelling odor, dogs sniff rapidly — roughly the equivalent of breathing in and out about 400 times per minute — which brings a large volume of air into the nose to improve sense of smell.”

Here, the dogs were smelling distinct skin odors since people who carry malaria parasites produce volatile molecules from their skin. Because the parasite goes through several stages of development as the malaria infection worsens, the scientists think the odor changes even further when the parasite reaches a certain stage of maturity.

Dogs, canine cognition expert Alexandra Horowitz, Ph.D. tells Inverse, are better equipped to pick out different smells than we are — while humans can smell plenty of things, we need to be trained to identify certain scents. Meanwhile, dogs don’t need training; they only need to be taught to tell us when they’ve found a smell.

This new study claims the malaria-sniffing dogs may even get better at sniffing out the disease. This study was to simply show that it was possible — in the future if they were exposed to children actually sick with the same type of parasites, rather than just socks, the researchers expect their success rate to increase.

Nathaniel Tall, Ph.D., a Texas Tech University assistant professor whose lab studies dogs’ sense of smell, says that dogs are a “great first step” when it comes to diagnosing illnesses.

“As we learn more about the use of volatile chemicals as potential signals of disease, dogs will likely be at the forefront of that development,” Tall tells Inverse. “In the future, specifically engineered equipment may replace the dog’s role in a laboratory setting. The dog, however, is likely to remain particularly successful in comparison to electronic sensors when deployed in remote areas because they work very well outside of a ‘clean’ laboratory environment.”