An ongoing testing program conducted by the Colorado Division of Wildlife has found that chronic wasting disease is still confined to a small portion of northeastern Colorado. It has not spread to deer herds elsewhere in the state.
“Based on our testing, CWD is still confined to the endemic area in northeastern Colorado,” said Division veterinarian Mike Miller. “We’ve examined more than 1,500 animals from throughout the state including Middle and North Park, the Gunnison area, the Uncompahgre Plateau, San Luis Valley the Piceanace Basin, the Colorado Springs and Canon City areas, and other areas in northwestern Colorado over the past four years,” Miller said. “None have been infected with wasting disease.”
Chronic wasting disease is a transmissible spongiform encaphelopathy, or TSE, that includes such diseases as scrapie in sheep, bovine spongiform enceophalopathy (BSE) in cattle, Creutzfeld Jacobs Disease (CJD), a rare brain disease in humans, and Kuru once found among New Guinea tribesmen who ate the brains of their dead relatives.
Miller has worked closely with state and federal health officials because BSE, dubbed “mad cow disease” in Great Britain, has been linked to more than 80 fatal cases of a new variant of Creutezfeld Jacobs disease in humans.
State and federal officials say there is no evidence to link chronic wasting disease to naturally occurring TSEs in humans.
More than 200 animals taken by hunters last fall were examined, Miller said. Tests conducted this fall in the area in northeastern Colorado where wasting disease already exists shows the incidence of the disease remains about five percent.
“The level of infection hasn’t changed appreciably since we began testing five years ago,” Miller said. “The pathogen seems to be firmly established in the endemic area, but transmission does not appear to be accelerating.”
Chronic wasting disease attacks the brains of infected deer and elk and is fatal. Infected animals appear disoriented, lose weight and lose control of bodily functions as their overall body condition deteriorates. The animal dies within a few weeks or months of the first symptoms.
The disease was first noted in the late 1960s but was likely present prior to that. Wildlife officials don’t know how it began and why is has only been found in portions of northeastern Colorado and southeastern Wyoming. Infection rates in deer have ranged from one to 15 percent in those areas.
Experiments underway in several states to determine if CWD could be transmitted to cattle has shown that it is extremely difficult to infect cattle with the pathogen. The only way researchers have been able to infect cattle is to directly inject the CWD pathogen into the brains of test animals. Cattle that have been in close contact with infected deer or have ingested the pathogen have not developed the disease. “Based on this research, it appears that there is a good biological barrier between the transmission of CWD between deer and cattle,” Miller said.
BSE, or mad cow disease, has never been found in the United States, nor have their been any cases of the new variant of CJD in the U.S. Other TSEs, including scrapie in sheep, have existed in the U.S. for decades, but health studies have found no link between scrapie and any human disease.
The Division continues to recommend that hunters not take animals that appear to be sick no matter the cause. Animals that appear to be diseased should not be consumed. They also recommend that the brain and nervous tissue of deer and elk not be consumed. The consumption of these organs by humans does not normally occur.
Hunters who field dress game animals should wear protective gloves, especially if they have open cuts or wounds on their hands. They should also carefully wash knives and other tools used to field dress game.
Miller said hunters have reported a number of animals that appear to be sick. Most have been ill with other diseases such as hemorragic disease and other bacterial or viral infections, injuries or old age. “If hunters, landowners or others see ill animals, they should report them to the local Division office,” Miller said.
Last November, the Colorado Wildlife Commission approved a late deer hunting season in Game Management Unit 9 north of Fort Collins as part of the DOW’s efforts to reduce the incidence of chronic wasting disease. Only deer hunters who had previously obtained permission from private landowners were allowed to purchase a deer license at the Division’s Fort Collins office. “If hunters don’t have permission for this hunt from a private landowner, they may not participate,” Miller said.