POSITIVE CHRONIC WASTING DISEASE TEST CONFIRMED
Laboratory testing verifies state’s first occurrence of disease in wild deer
PRATT -- The National Veterinary Services Laboratory in Ames, Iowa has verified the preliminary lab test conducted last week, which was positive for Kansas’ first occurrence of chronic wasting disease (CWD) in a wild deer. Tissue samples from the deer, taken by a resident hunter in Cheyenne County during the state’s firearms season in December, were initially tested at a Kansas State University lab, then submitted to the lab in Iowa for confirmation.
Kansas Department of Wildlife and Parks biologists will sample additional deer in Cheyenne County to help determine whether the disease exists in other deer in the vicinity, a strategy outlined in a contingency plan the department first developed in 2003 after CWD expanded in Colorado, Wyoming, and Nebraska. CWD has been documented in ten states. The department also is planning to conduct a public meeting in St. Francis to provide more information on CWD and strategies to minimize the potential for spread of the disease.
CWD attacks the central nervous system of infected animals, and is within a group of similar diseases known as transmissible spongiform encephalopathies (TSE). While CWD can spread among deer and elk, it is not known to transmit to humans, livestock, or other animals.
KDWP biologists have collected tissue samples from deer taken by Kansas hunters since 1996 to monitor deer herd health. During the past firearms deer season, tissue samples were collected from deer in five western deer management units, covering most of the western half of the state. Western units were sampled because biologists anticipated that was where an occurrence would most likely be found.
The department will post updated information on its website as further sampling and evaluation occurs. Contact Bob Mathews at KDWP’s Pratt office (620/672-5911 or email) for more information. More information on chronic wasting disease is also available on the Internet at http://www.cwd-info.org.
PUBLIC MEETING PLANNED ON CHRONIC WASTING DISEASE
Cheyenne County Fairgrounds site of Feb. 2 informational discussion
The Kansas Department of Wildlife and Parks will conduct an informational meeting at 7 p.m. Feb. 2 at the Cheyenne County Fairgrounds in St. Francis. KDWP and Kansas Animal Health Department officials will discuss the occurrence of chronic wasting disease (CWD) in a deer taken by a hunter in Cheyenne County during the 2005 firearms deer season.
Department and cooperating agency staff will provide more information on CWD, outline strategies to monitor the disease in Kansas, and answer questions from meeting participants.
On Jan. 23rd, the National Veterinary Services Laboratory in Ames, Iowa notified KDWP that it had verified the preliminary lab test, which was positive for Kansas’ first occurrence of chronic wasting disease (CWD) in a wild deer.
CWD has been documented in ten states. The disease attacks the central nervous system of infected animals, and is within a group of similar diseases known as transmissible spongiform encephalopathies (TSE). While CWD can spread among deer and elk, it is not known to transmit to humans, livestock, or other animals. Since 1996, KDWP biologists have annually collected tissue samples from deer taken by Kansas hunters, to monitor deer herd health.
The department will post updated information on its website as further sampling and evaluation occurs. Contact Bob Mathews at KDWP’s Pratt office (620/672-5911) for more information. More information on chronic wasting disease is also available on the Internet.
Kansas plans hunt to evaluate wasting disease
By ROXANA HEGEMAN
Associated Press writer Friday, January 27, 2006
WICHITA, Kan. -- Researchers plan to kill and test deer to determine how widespread the infestation of chronic wasting disease is in the state's wildlife population now that Kansas has confirmed its first case of the brain-destroying ailment.
Biologists at the Kansas Department of Wildlife and Parks began meeting Wednesday to decide how many brain tissue samples they must collect from whitetail and mule deer in the area where the first case was found, said Bob Mathews, spokesman for the department.
Because no test exists for live animals, enough deer will have to be killed to obtain a statistically reliable sample, Mathews said.
"We aren't going to dodder on this thing. We are going to move as quickly as possible on whatever additional sampling will occur in the next few weeks," he said.
A decision on the length and regulations for the 2006 deer season is typically made at the April meeting of the Wildlife and Parks Commission. Wildlife officials currently have nothing under consideration that would limit hunting anywhere in the state.
"First we have to establish whether this occurrence was limited to a single animal or whether it may occur to others in that vicinity. That is why we are sampling," Mathews said.
Subject: Prions in Skeletal Muscles of Deer with Chronic Wasting Disease [SCIENCE FULL TEXT]
Date: January 26, 2006 at 12:23 pm PST
Prions in Skeletal Muscles of Deer with Chronic Wasting Disease
Rachel C. Angers,1* Shawn R. Browning,1*† Tanya S. Seward,2 Christina J. Sigurdson,4‡ Michael W. Miller,5 Edward A. Hoover,4 Glenn C. Telling1,2,3§
1Department of Microbiology, Immunology and Molecular Genetics, 2Sanders Brown Center on Aging, 3Department of Neurology, University of Kentucky, Lexington, KY 40536, USA. 4Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA. 5Colorado Division of Wildlife, Wildlife Research Center, Fort Collins, CO 80526, USA.
*These authors contributed equally to this work.
†Present address: Department of Infectology, Scripps Research Institute, 5353 Parkside Drive, RF-2, Jupiter, Florida, 33458, USA.
‡Present address: Institute of Neuropathology, University of Zurich, Schmelzbergstrasse 12, 8091 Zurich, Switzerland.
Prions are transmissible proteinaceous agents of mammals that cause fatal neurodegenerative diseases of the central nervous system (CNS). The presence of infectivity in skeletal muscle of experimentally infected mice raised the possibility that dietary exposure to prions might occur through meat consumption (1). Chronic wasting disease (CWD), an enigmatic and contagious prion disease of North American cervids, is of particular concern. The emergence of CWD in an increasingly wide geographic area and the interspecies transmission of bovine spongiform encephalopathy (BSE) to humans as variant Creutzfeldt Jakob disease (vCJD) have raised concerns about zoonotic transmission of CWD.
To test whether skeletal muscle of diseased cervids contained prion infectivity, Tg(CerPrP)1536 mice (2) expressing cervid prion protein (CerPrP), were inoculated intracerebrally with extracts prepared from the semitendinosus/semimembranosus muscle group of CWD-affected mule deer or from CWD-negative deer. The availability of CNS materials also afforded direct comparisons of prion infectivity in skeletal muscle and brain. All skeletal muscle extracts from CWD-affected deer induced progressive neurological dysfunction in Tg(CerPrP)1536 mice with mean incubation times ranging between 360 and ~490 d, whereas the incubation times of prions from the CNS ranged from ~230 to 280 d (Table 1). For each inoculation group, the diagnosis of prion disease was confirmed by the presence of PrPSc in the brains of multiple infected Tg(CerPrP)1536 mice (see supporting online material for examples). In contrast, skeletal muscle and brain material from CWD-negative deer failed to induce disease in Tg(CerPrP)1536 mice (Table 1) and PrPSc was not detected in the brains of sacrificed asymptomatic mice as late as 523 d after inoculation (supporting online material).
Our results show that skeletal muscle as well as CNS tissue of deer with CWD contains infectious prions. Similar analyses of skeletal muscle BSE-affected cattle did not reveal high levels of prion infectivity (3). It will be important to assess the cellular location of PrPSc in muscle. Notably, while PrPSc has been detected in muscles of scrapie-affected sheep (4), previous studies failed to detect PrPSc by immunohistochemical analysis of skeletal muscle from deer with natural or experimental CWD (5, 6). Since the time of disease onset is inversely proportional to prion dose (7), the longer incubation times of prions from skeletal muscle extracts compared to matched brain samples indicated that prion titers were lower in muscle than in CNS where infectivity titers are known to reach high levels. Although possible effects of CWD strains or strain mixtures on these incubation times cannot be excluded, the variable 360 to ~490 d incubation times suggested a range of prion titers in skeletal muscles of CWD-affected deer. Muscle prion titers at the high end of the range produced the fastest incubation times that were ~30% longer than the incubation times of prions from the CNS of the same animal. Since all mice in each inoculation group developed disease, prion titers in muscle samples producing the longest incubation times were higher than the end point of the bioassay, defined as the infectious dose at which half the inoculated mice develop disease. Studies are in progress to accurately assess prion titers.
While the risk of exposure to CWD infectivity following consumption of prions in muscle is mitigated by relatively inefficient prion transmission via the oral route (8), these
results show that semitendinosus/semimembranosus muscle, which is likely to be consumed by humans, is a significant source of prion infectivity. Humans consuming or handling meat from CWD-infected deer are therefore at risk to prion exposure.
All of us, at one time or another have gone on a hunting trip and had what we call “Blue Bird” weather. Warm evenings and almost hot days. We hunt in our t-shirts and enjoy the sunshine. We are way up in the mountains and have a whole week to hunt. How could it get any better?
That is, until we score on that big buck or bull. We work to get it out of the field and skinned as quickly as possible to cool it down. But try as we might, we just can’t get...