Currently, in order to check if someone has malaria but isn't showing any symptoms yet, a blood sample has to be drawn and analyzed. Thanks to an ongoing research project, however, it may soon be possible to detect the disease on the spot within seconds – using sniffer dogs.
Led by scientists from the UK's Durham University, an international team of scientists gathered foot odor samples from a group of 175 seemingly-healthy children aged five to 14 in the Upper River Region of The Gambia in West Africa. Each child was asked to wear a pair of nylon socks overnight for one night, after which the socks were collected, frozen, and sent to the Medical Detection Dogs facility in Britain.
The children were also each subjected to a finger-prick blood test, in order to determine if they were unknowingly carrying the Plasmodium falciparum malaria parasite in their bloodstream. It turned out that 30 of them were infected.
While the socks were in cold storage for several months, two dogs at the facility – a labrador-golden retriever cross called Lexi and a labrador called Sally – were trained to distinguish between the body odor of children infected with the parasite, and those who were not. When the trained dogs subsequently sniffed the socks, they were 70 percent accurate at indicating those that came from the 30 infected children, and 90 percent accurate at telling which ones came from the 145 non-infected individuals.
It is thought that the accuracy rates would be considerably higher if the dogs were able to smell the children directly, or if the socks hadn't been kept frozen for so long. Additionally, while the dogs had been trained to detect the human body scent caused by the parasite when it's at a fairly early stage of its life cycle, the parasites in some of the infected children were at a more advanced stage, so they likely produced a different odor.
The scientists believe that with additional training and more samples to work from, sniffer dogs could approach the accuracy of traditional blood tests. They could then be used not only in resource-poor regions that lack lab equipment, but also in ports of entry such as airports, where they could keep malaria-carrying travellers from entering malaria-free countries and spreading the disease.
The research was presented this Monday at the American Society of Tropical Medicine and Hygiene Annual Meeting, in New Orleans.
Sources: Durham University, American Society of Tropical Medicine and Hygiene