April 10, 2009
Infrared thermography (IRT) cameras can see what human eyes can't: heat. That is why scientists at the Agricultural Research Service (ARS) Plum Island Animal Disease Center (PIADC) at Orient Point, N.Y., are using the technology to identify cattle that may have been infected with foot-and-mouth disease (FMD).
The United States hasn't had an outbreak of FMD since 1929, but there is no way to guarantee that this very contagious disease is gone forever-as the United Kingdom learned in 2001, when an outbreak of FMD ended a 34-year, disease-free streak. The disease spreads rapidly and wreaks havoc on trade and transportation, so being prepared for an outbreak is a priority for the U.S. government. An essential component of containment and eradication is the ability to quickly assess the scope of an outbreak.
Luis Rodriguez, PIADC research leader, and his colleagues evaluated a new method for rapidly and accurately detecting animals at risk of infection. Their method, which uses IRT cameras to quickly identify potentially infected animals, is not intended to be a diagnostic test. Rather, it enables scientists to concentrate their resources by quickly isolating animals that require further testing with a disease-specific method.
IRT cameras can identify at-risk cattle 48 hours before they begin to show any clinical symptoms. In the event of an outbreak, this technology could facilitate rapid containment of the disease.
How does it work? Objects of all temperatures above absolute zero (about -460°F) emit infrared radiation. The hotter the object, the higher the emissions, and IRT cameras make those emissions visible.
Foot temperatures rise in cattle infected with the FMD virus, resulting in a visible difference in IRT photographs. In an IRT photograph of a group of cattle, the hooves of healthy animals appear blue-green, whereas infected cattle have orange-red feet. This easy visual distinction could allow scientists and veterinarians to identify potentially infected cattle in large groups without examining animals individually. The technology is cheaper and faster than existing screening methods, which involve individual clinical examinations for every animal.
The full story is available at www.ars.usda.gov/is/AR/archive/apr09/