Dogs can sniff out malaria, study shows

New research shows that sniffer dogs can diagnose malaria quickly and accurately.

(Online) - New research shows that sniffer dogs can diagnose malaria quickly and accurately, even when people do not exhibit any symptoms.

New research shows that sniffer dogs can diagnose malaria quickly and accurately, even when people do not exhibit any symptoms.

Dogs can pick up odors that develop on human skin due to malaria parasites.

Malaria was responsible for445,000 global deaths in 2016, according to the World Health Organization (WHO). In total, 216 million infections were registered worldwide that year.

In the United States, doctors diagnose about 1,500 cases of malaria each year, according to the Centers for Disease Control and Prevention (CDC).

Although the number of infections is relatively small, a delay in diagnosis is the primary cause of death among people with malaria in the U.S. Currently, a person’s physical symptoms determine diagnosis, but, ideally, the CDC recommends that laboratory tests such as microscopic analyses of blood smears should confirm the symptoms.

New research, however, shows that dogs can diagnose the infection quickly, accurately, and in a noninvasive way. Steven Lindsay, a public health entomologist at the Department of Biosciences at Durham University in the United Kingdom, is the lead investigator of the new study.

Lindsay summarized the findings at the American Society of Tropical Medicine and Hygiene (ASTMH) Annual Meeting, which this year took place in New Orleans, LA.

"People with malaria parasites generate distinct odors on their skin, and our study found dogs, which have an incredibly sensitive sense of smell, can be trained to detect these odors even when it’s just on an article of clothing worn by an infected person."

As the study’s lead author explains, the research began in The Gambia, where specialists tested hundreds of school children for malaria parasites and gave them a pair of socks to wear overnight.

The researchers collected the socks the next day, sorted them according to the children’s status of malaria infection, and stored them in a freezer for several months. Lindsay and colleagues only collected socks from children who had malaria but did not develop fever, as well as children who did not have the parasite.

In the meantime, experts at the Medical Detection Dogs charity trained dogs to freeze if they detected malaria, or move on if they did not. In this experiment, using the sock alone, the dogs accurately identified 70 percent of the malaria infections and 90 percent of the children who did not have the disease.

The researchers report that the levels of parasites identified by the dogs were lower than those required by existing "rapid diagnostic tests," which offer a diagnosis in 2–15 minutes.

Also, Lindsay says that the diagnostic accuracy rate might have been even higher if the children were all carrying parasites that were in a similar stage of development.

The researcher explains that as the infection advances, the parasite goes through different stages, and when it reaches a level of maturity, its odor on the human skin might change. The dogs were not trained to detect these mature parasites.

Finally, the researchers think that the accuracy rate would have also been higher if the dogs had access to more recently worn socks, rather than frozen socks.