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2011-04-14

Animals as Sentinels

Can animals help us detect threats to human health? Dr. Larry Glickman has convinced me that they can be part of the system to detect and understand threats to humans. (If I make any errors or misrepresentations with the following, the fault is mine.)

Everyone has heard of the practice of taking a canary down into a coal mine to check for toxic gases. Larry referred to that practice in a presentation sponsored by the Triangle Global Health Consortium One Health Collaborative. He noted that canaries have been used as sentinels for detecting harmful levels of carbon monoxide and methane in coal mines since 1918. As late as 1995, canaries were used in Japan to detect harmful gases in environmental disasters.

Why canaries? It has to do with their greater sensitivity to noxious gases compared to human beings. Why other animals? That has as much to do with our lifestyles as the animals' sensitivity to health threats. We live with lots of animals as companions. More than a third of American households have dogs and almost that proportion have cats according to the AVMA. With over 150 million dogs and cats literally living with us, we should be looking to that population as health sentinels.

Larry mentioned several instances where animal populations are useful in understanding threats to human health. Ticks bring a number of diseases into the human sphere including Rocky Mountain Spotted Fever and Lyme Disease. Larry described techniques for using dogs to assess the tick population to develop advance warning of Lyme Disease.

One of his most compelling explorations was using dogs and cats as sentinels in the aftermath of an unintentional release of propyl mercaptan from a waste-processing facility in Fairburn, Georgia. The concern was that human beings might ascribe unrelated medical issues to the disaster. Larry led a team that sought to find a better way to seek the truth by looking at the dogs and cats in the area of the disaster. He used veterinary medical information from a chain of clinics that used the same electronic medical records to look for symptoms that would be produced by the chemical released. In fact, he and his colleagues found that the release "showed no conclusive and consistent evidence of adverse health effects." No smoking gun, but at least we had an independent and verifiable way to get to the truth.

Can we use animal health data to look for ongoing threats to human health. You bet. More on that topic to come.