When chronic wasting disease was discovered south of Hayden in 2002, Northwest Colorado residents and the Colorado Division of Wildlife scrambled to establish a local testing facility.
Residents anticipated economic impacts caused by a loss of hunters, who might be scared off by CWD. In months, the facility was established, and supporters applauded the notion that hunters could find out if the animals they harvested were free of the disease.
Last fall, more than 15,000 deer, elk and moose heads were tested for chronic wasting disease statewide. Thousands of tissue specimens were taken at a sampling site at the north end of Yampa Avenue in Craig.
The samples provided the Division of Wildlife with valuable information about the prevalence of the disease and its geographic distribution.
But according to a 2004 report by the U.S. Department of Agriculture, the screening cannot be considered a food safety test.
"(A) negative test result is not necessarily a reliable indicator that an animal is free of the disease," the report stated. The next sentence, which is underlined in the report, reads, "Indeed, at this time there is no test that can be used reliably on individual animals to determine whether that animal is free from CWD."
DOW spokesman Todd Malmsbury said the DOW admits that fact in print, in its annual big game brochure and on its Web site. From the DOW's standpoint, the tests serve as a surveillance tool, Malmsbury said.
Some hunters, however, may be under the impression that a negative test means a disease-free animal.
The USDA reported that "the demand for test results to provide to hunters implies food safety testing."
"The tests for CWD are not meant to be food safety tests," said Suzan Holl, a spokeswoman for the USDA's Animal and Plant Health Inspection Service. "The tests are specifically for surveillance purposes."
The disease's long incubation period could mean that some animals that have the disease do not test positive for it. "False negatives," may occur during the early stages of infection, according to the USDA.
"In addition, relatively little is known about the distribution of the CWD agent, so an animal whose brain and nervous system tissue tests negative actually might be carrying the infective agent in other tissues," the USDA reported.
The "infective agent," thought to be a misshapen protein called a prion, has not been found in muscle tissue. It is concentrated in the lymph nodes, brain, spinal column and other tissues.
In deer and elk, the disease causes emaciation, abnormal behavior, loss of bodily functions and death. Malmsbury reiterated that there is no evidence of a link between CWD and human health risks.
CWD is related to mad cow disease in cattle, which has been shown to infect humans.
Health officials and the DOW advise people not to eat meat from animals known to be infected. The DOW also advocates precautions, such as using rubber gloves when field dressing big game.