Disease-detecting dogs and mice may be trained to sniff out bird influenza and other deadly illnesses before they spread, suggests new research reported today at the National Meeting of the American Chemical Society.
Rodents on little leashes marching through airplanes might at first seem unlikely, but trained rats have already been recruited to detect land mines. Bloodhounds, cadaver dogs and other canines already use their noses to benefit humans, so disease detection may be a logical next step.
Project leader Bruce Kimball, a U.S. Department of Agriculture scientist, told Discovery News that if the research continues to progress, "we envision working dogs trained to identify the presence of avian influenza in bird populations by having them search for signals in the environment -- basically anywhere that feces may be present."
"We have plans to extend this same sort of inquiry to detection of diseases that may be transmitted to livestock through wildlife," Kimball added.
The key to the whole process is smelly poop.
As it turns out, the excrement of infected animals smells different than the feces of healthy individuals.
To see if mammals could be trained to identify infected dung, Kimball and scientists at the Monell Chemical Senses Center placed mice in a maze and gave the rodents a refreshing drink of water every time they zeroed in on a feces sample from an infected duck. Eventually, the mice became experts at identifying such infected excrement.
To protect the mice and people during the experiment, the scientists irradiated the feces to inactivate all shed viruses.
"However, the mice are never in contact with the feces," explained Kimball. "They are only exposed to the volatile odors released from feces, thus it remains possible to detect avian influenza infection without the animals having to come in contact with the virus."
"Of course, we have to determine if irradiation significantly contributed to the production of the odor indicative of infection," he added.
The research is part of a collaboration involving the USDA, Monell, Animal and Plant Health Inspection Service, Wildlife Services and the National Wildlife Research Center to prevent the spread and transmission of disease.
From pathogens in eggs to avian flu, zoonotic diseases have been on the rise in recent years, so there is interest now in developing diagnostic tools that use odor as a means to detect disease.
Excrement may be just one source of that odor.
Prior research led by Michael McCulloch of the Pine Street Foundation and Tadeusz Jezierski of the Polish Academy of Sciences determined that dogs smell disease on a person's breath. In this case, the researchers focused on lung and breast cancer. Dogs sniffed out the cancers with 88 to 97 percent accuracy.
It remains unclear as to what chemical compounds produce the disease odors in both breath and feces, but the researchers hope to eventually identify those and create an artificial electronic nose that could handle disease surveillance in future.