Tom Morang
03-22-2002, 06:36 PM
First live animal test for chronic wasting
disease succeeds
By Environmental News Network
Wednesday, December 12, 2001
For the first time, a live animal test has been developed for a disease
related to mad cow disease. The test has been used to detect chronic
wasting disease in live elk and deer.
A test for chronic wasting disease that samples tonsil tissue from live
mule deer has been developed by the Colorado Division of Wildlife
(DOW), providing a new tool to help prevent the spread and reduce the
prevalence of the disease in wild and captive deer herds.
Chronic wasting disease is a fatal illness found in wild deer and elk in
northeastern Colorado and southeastern Wyoming. Two wild deer with
the disease have been found in extreme northwestern Nebraska and
two were found in western Saskatchewan earlier this year.
The Colorado Division of Wildlife, working with Colorado State
University in Fort Collins and the University of Wyoming in Laramie,
began a research project earlier this year to determine if the live test
would be accurate and effective.
"The availability of a reliable test for diagnosing chronic wasting
disease in live mule deer offers us several opportunities for advancing
both the understanding and management of this important wildlife
disease," said DOW veterinarian Mike Miller, who led the study in
collaboration with DOW researcher Tom Hobbs.
"Early detection and removal of chronic-wasting-disease-infected
animals appears to be the most effective method for managing CWD,"
Miller said. "Selective culling of positive animals and animals in contact
with these positive individuals should help reduce the prevalence rates
in endemic areas."
Chronic wasting disease — thought to be caused by infectious proteins
known as prions — was first recognized as a clinical wasting syndrome
in 1967 in mule deer in a wildlife research facility in northern Colorado.
It was identified as a transmissible spongiform encephalopathy (TSE) in
1978.
The disease attacks the brains of infected deer and elk, causing the
animals to become thin, display abnormal behavior, lose bodily
functions, and die.
About 5 percent of deer and less than 1 percent of elk are infected with
chronic wasting disease in the endemic areas of Colorado. The disease
has never been found in wild deer and elk in other parts of the state.
Elizabeth Williams, a professor of veterinary science at the University of
Wyoming and a pathologist at the state veterinary laboratory said the
disease is also present in captive herds in five states.
The first positive farmed herd in the United States was detected in
1997 in South Dakota, said the U.S. Agriculture Department's Animal
and Plant Health Inspection Service (APHIS). Since then, 16 additional
positive herds have been found: 6 in South Dakota, 3 in Nebraska, 5 in
Colorado, and 1 each in Oklahoma and Montana. As of October 2001, 6
of these 17 positive herds remained under state quarantine. APHIS said
that 10 of the herds have been depopulated or have been slaughtered
and tested, and the quarantine has been lifted from one herd that
underwent rigorous surveillance with no further evidence of disease.
There is no known cure for chronic wasting disease, and researchers
don't know how the disease began. It is related to bovine spongiform
encephalopathy (BSE), commonly known as mad cow disease, which is
also caused by infectious prions. A live animal test for BSE has yet to
be found.
Miller cautioned that the new test will not work in all situations and
won't replace the current testing of animals after they have been killed
by hunters or wildlife managers.
"Despite some promising aspects, we recognize the test's practical
limitations," Miller said. "The need to capture, anesthetize, and
precisely sample individual deer limits the broad implementation of this
testing approach in managing free-ranging deer populations infected
with chronic wasting disease."
The new test on tonsil tissue is more sensitive than examining the
brain tissue of animals killed by the illness — the current standard test
for chronic wasting disease — because prions congregate in the tonsils
early in the disease's development. Testing of tonsil tissue is equally
effective in both live deer and deer who have been killed by hunters or
during culling efforts.
But the test isn't effective for elk because the disease develops
differently in the two species. There still is no live test for elk.
Research was conducted last spring and summer on 160 mule deer in
the Estes Park and Livermore areas along Colorado's northern Front
Range. The effort began because researchers knew from earlier studies
that prions accumulate in the tonsils early in the disease and remain in
the animal. The tests involve tranquilizing deer, taking biopsies from
the animals' tonsils, then collaring and releasing the deer. The biopsies
are then analyzed in a laboratory.
Miller said the new test may be particularly useful where hunting
doesn't occur, such as urban and suburban areas and inside Rocky
Mountain National Park.
The new live test may allow wildlife managers to determine if the
illegal feeding of deer is a factor in spreading the disease. Feeding by
humans attracts many animals to small areas, increasing the chance
that chronic wasting disease will spread.
Feeding of deer may be a factor in the high incidence of the disease in
urban areas and subdivisions in Estes Park and locations northwest of
Fort Collins.
Colorado and federal health officials say that it is unlikely that chronic
wasting disease is naturally transmissible to humans or to animals
other than deer or elk. They also note that mad cow disease has never
been found in the United States.
disease succeeds
By Environmental News Network
Wednesday, December 12, 2001
For the first time, a live animal test has been developed for a disease
related to mad cow disease. The test has been used to detect chronic
wasting disease in live elk and deer.
A test for chronic wasting disease that samples tonsil tissue from live
mule deer has been developed by the Colorado Division of Wildlife
(DOW), providing a new tool to help prevent the spread and reduce the
prevalence of the disease in wild and captive deer herds.
Chronic wasting disease is a fatal illness found in wild deer and elk in
northeastern Colorado and southeastern Wyoming. Two wild deer with
the disease have been found in extreme northwestern Nebraska and
two were found in western Saskatchewan earlier this year.
The Colorado Division of Wildlife, working with Colorado State
University in Fort Collins and the University of Wyoming in Laramie,
began a research project earlier this year to determine if the live test
would be accurate and effective.
"The availability of a reliable test for diagnosing chronic wasting
disease in live mule deer offers us several opportunities for advancing
both the understanding and management of this important wildlife
disease," said DOW veterinarian Mike Miller, who led the study in
collaboration with DOW researcher Tom Hobbs.
"Early detection and removal of chronic-wasting-disease-infected
animals appears to be the most effective method for managing CWD,"
Miller said. "Selective culling of positive animals and animals in contact
with these positive individuals should help reduce the prevalence rates
in endemic areas."
Chronic wasting disease — thought to be caused by infectious proteins
known as prions — was first recognized as a clinical wasting syndrome
in 1967 in mule deer in a wildlife research facility in northern Colorado.
It was identified as a transmissible spongiform encephalopathy (TSE) in
1978.
The disease attacks the brains of infected deer and elk, causing the
animals to become thin, display abnormal behavior, lose bodily
functions, and die.
About 5 percent of deer and less than 1 percent of elk are infected with
chronic wasting disease in the endemic areas of Colorado. The disease
has never been found in wild deer and elk in other parts of the state.
Elizabeth Williams, a professor of veterinary science at the University of
Wyoming and a pathologist at the state veterinary laboratory said the
disease is also present in captive herds in five states.
The first positive farmed herd in the United States was detected in
1997 in South Dakota, said the U.S. Agriculture Department's Animal
and Plant Health Inspection Service (APHIS). Since then, 16 additional
positive herds have been found: 6 in South Dakota, 3 in Nebraska, 5 in
Colorado, and 1 each in Oklahoma and Montana. As of October 2001, 6
of these 17 positive herds remained under state quarantine. APHIS said
that 10 of the herds have been depopulated or have been slaughtered
and tested, and the quarantine has been lifted from one herd that
underwent rigorous surveillance with no further evidence of disease.
There is no known cure for chronic wasting disease, and researchers
don't know how the disease began. It is related to bovine spongiform
encephalopathy (BSE), commonly known as mad cow disease, which is
also caused by infectious prions. A live animal test for BSE has yet to
be found.
Miller cautioned that the new test will not work in all situations and
won't replace the current testing of animals after they have been killed
by hunters or wildlife managers.
"Despite some promising aspects, we recognize the test's practical
limitations," Miller said. "The need to capture, anesthetize, and
precisely sample individual deer limits the broad implementation of this
testing approach in managing free-ranging deer populations infected
with chronic wasting disease."
The new test on tonsil tissue is more sensitive than examining the
brain tissue of animals killed by the illness — the current standard test
for chronic wasting disease — because prions congregate in the tonsils
early in the disease's development. Testing of tonsil tissue is equally
effective in both live deer and deer who have been killed by hunters or
during culling efforts.
But the test isn't effective for elk because the disease develops
differently in the two species. There still is no live test for elk.
Research was conducted last spring and summer on 160 mule deer in
the Estes Park and Livermore areas along Colorado's northern Front
Range. The effort began because researchers knew from earlier studies
that prions accumulate in the tonsils early in the disease and remain in
the animal. The tests involve tranquilizing deer, taking biopsies from
the animals' tonsils, then collaring and releasing the deer. The biopsies
are then analyzed in a laboratory.
Miller said the new test may be particularly useful where hunting
doesn't occur, such as urban and suburban areas and inside Rocky
Mountain National Park.
The new live test may allow wildlife managers to determine if the
illegal feeding of deer is a factor in spreading the disease. Feeding by
humans attracts many animals to small areas, increasing the chance
that chronic wasting disease will spread.
Feeding of deer may be a factor in the high incidence of the disease in
urban areas and subdivisions in Estes Park and locations northwest of
Fort Collins.
Colorado and federal health officials say that it is unlikely that chronic
wasting disease is naturally transmissible to humans or to animals
other than deer or elk. They also note that mad cow disease has never
been found in the United States.