Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of deer, elk (wapiti), and moose. TSEs are caused by unusual infectious agents known as prions. To date, CWD has been found mainly in cervids (members of the deer family). 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 TSE in 1978 and has spread to a dozen states and two Canadian provinces.^[1] CWD is typified by chronic weight loss leading to death. There is no known relationship between CWD and any other TSE of animals or people. Although there have been reports in the popular press of humans being affected by CWD, a study by the CDC failed to find any relationship.^[2] Transmissible spongiform encephalopathies (TSEs, also known as prion diseases) are a group of progressive conditions that affect the brain and nervous system of humans and animals and are transmitted by prions. ... This article is about the ruminent animal. ... For other uses, see Elk (disambiguation). ... For other uses, see Moose (disambiguation). ... This false-colored electron micrograph shows a malaria sporozoite migrating through the midgut epithelia. ... For the bird, see Prion (bird). ... Genera About 15 in 4 subfamilies. ... Year 1967 (MCMLXVII) was a common year starting on Sunday (link will display full calendar) of the 1967 Gregorian calendar. ... Binomial name (Rafinesque, 1817) The mule deer (Odocoileus hemionus) is a deer whose habitat is in the western half of North America. ... Official language(s) English Demonym Coloradan Capital Denver Largest city Denver Largest metro area Denver-Aurora Metro Area Area  Ranked 8th in the US  - Total 104,185 sq mi (269,837 km²)  - Width 280 miles (451 km)  - Length 380 miles (612 km)  - % water 0. ... Year 1978 (MCMLXXVIII) was a common year starting on Sunday (link displays the 1978 Gregorian calendar). ... The Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, is recognized as the leading United States agency for protecting the public health and safety of people. ...

Clinical signs

Most cases of CWD occur in adult animals. The disease is progressive and always fatal. The most obvious and consistent clinical sign of CWD is weight loss over time. Behavioral changes also occur in the majority of cases, including decreased interactions with other animals, listlessness, lowering of the head, blank facial expression, and repetitive walking in set patterns. In elk, behavioral changes may also include hyperexcitability and nervousness. Affected animals continue to eat grain but may show decreased interest in hay. Excessive salivation and grinding of the teeth also are observed. Most deer show increased drinking and urination. For other uses, see Hay (disambiguation). ...

Causative agent

The agent responsible for CWD (and other TSEs, such as scrapie and bovine spongiform encephalopathy) is a prion, an abnormal form of a normal protein, known as prion protein (PrP), most commonly found in the central nervous system (CNS), and is capable of spreading to the peripheral nervous system (PNS), thus infecting meat, or muscle, of deer and elk. The abnormal prion protein infects the host animal by promoting conversion of normal cellular prion protein (PrP^C) to the abnormal prion form (PrP^CWD). The build-up of PrP^CWD in the brain is associated with widespread neurodegeneration. Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. ... Classic image of a cow with BSE. A notable feature of such disease is the inability (of the infected animal) to stand. ... For the bird, see Prion (bird). ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... A diagram showing the CNS: 1. ... The Peripheral nervous system resides or extends outside the CNS central nervous system (the brain and spinal cord) to serve the limbs and organs. ... Neurodegenerative disease (Greek νέυρο-, néuro-, nerval and Latin dēgenerāre, to decline or to worsen) is a condition in which cells of the brain and spinal cord are lost. ...

Diagnosis

Research is being conducted to develop live-animal diagnostic tests for CWD. Currently, definitive diagnosis is based on postmortem examination (necropsy) and testing. Gross lesions seen at necropsy reflect the clinical signs of CWD, primarily emaciation. Aspiration pneumonia, which may be the actual cause of death, also is a common finding in animals affected with CWD. On microscopic examination, lesions of CWD in the central nervous system resemble those of other TSEs. In addition, scientists use a technique called immunohistochemistry to test brain tissue for the presence of the abnormal prion protein to diagnose CWD. For the former Death Metal band called Autopsy, see Autopsy (band). ... Aspiration pneumonia is a specific form of lung infection (pneumonia) that develops when oral or gastric contents (including food, saliva, or nasal secretions) enter the bronchial tree. ... Immunohistochemistry or IHC refers to the process of localizing proteins in cells of a tissue section exploiting the principle of antibodies binding specifically to antigens in biological tissues. ... For other uses, see Brain (disambiguation). ...

Epidemiology

The origin and mode of transmission of the prions causing CWD is unknown, but recent research indicates that prions can be excreted by deer and elk, and is transmitted by eating grass growing in contaminated soil.^[3][4] Animals born in captivity and those born in the wild have been affected with the disease. Based on epidemiology, transmission of CWD is thought to be lateral or from animal to animal; although maternal transmission may occur, it appears to be relatively unimportant in maintaining epidemics. Research has recently shown that an infected deer's saliva is able to spread the CWD prions.^[5] Epidemiology is the study of factors affecting the health and illness of populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine. ...

In the mid-1980s, CWD was detected in free-ranging deer and elk in contiguous portions of northeastern Colorado and southeastern Wyoming. Soon after diagnosis of the disease as a TSE, Colorado and Wyoming wildlife management agencies stopped the movement of deer and elk from their research facilities; wild cervids have not been translocated from the endemic area. In May 2001, CWD was also found in free-ranging deer in the southwestern corner of Nebraska (adjacent to Colorado and Wyoming) and later in additional areas in western Nebraska. The limited area of northern Colorado, southern Wyoming, and western Nebraska in which free-ranging deer, moose, and/or elk positive for CWD have been found is referred to as the endemic area. The area in 2006 has expanded to six states including parts of eastern Utah, southwestern South Dakota, and northeastern Kansas. There are also non-contigious (to the endemic area) areas in central Utah and central Nebraska. The limits of the affected areas are not well defined since the disease is at a low incidence and the amount of sampling may not be adequate to detect it. In 2002, CWD was detected in wild deer in south-central Wisconsin and northern Illinois and in an isolated area of southern New Mexico. In 2005, it was found in wild White-tailed deer in New York and West Virginia. It is also found in the Canadian provinces of Alberta and Saskatchewan. Official language(s) English Capital Cheyenne Largest city Cheyenne Area  Ranked 10th  - Total 97,818 sq mi (253,348 km²)  - Width 280 miles (450 km)  - Length 360 miles (580 km)  - % water 0. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... For other uses, see Nebraska (disambiguation). ... In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... This article is about the U.S. state. ... Official language(s) English Capital Pierre Largest city Sioux Falls Area  Ranked 17th  - Total 77,116[1] sq mi (199,905 km²)  - Width 210 miles (340 km)  - Length 380 miles (610 km)  - % water 1. ... This article is about the U.S. state. ... Also see: 2002 (number). ... This article is about the U.S. state. ... Official language(s) English[1] Capital Springfield Largest city Chicago Largest metro area Chicago Metropolitan Area Area  Ranked 25th  - Total 57,918 sq mi (140,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ... Official language(s) None Spoken language(s) English 68. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Binomial name Zimmermann, 1780 The White-tailed deer (Odocoileus virginianus), also known as the Virginia deer, or simply as the whitetail, is a medium-sized deer found throughout most of the continental United States, southern Canada, Mexico, Central America and northern portions of South America as far south as Peru. ... This article is about the state. ... Official language(s) English Capital Charleston Largest city Charleston Largest metro area Charleston metro area Area  Ranked 41st  - Total 24,244 sq mi (62,809 km²)  - Width 130 miles (210 km)  - Length 240 miles (385 km)  - % water 0. ... For other uses, see Alberta (disambiguation). ... This article is about the Canadian province. ...

Chronic wasting disease in North America

CWD also has been diagnosed in farmed elk and deer herds in a number of States and in two Canadian provinces. The first positive farmed elk herd in the United States was detected in 1997 in South Dakota. Since then, additional positive elk herds and farmed White-tailed deer herds have been found in South Dakota (7), Nebraska (4), Colorado (10), Oklahoma (1), Kansas (1), Minnesota (3), Montana (1), Wisconsin (6) and New York (2). As of fall of 2006, four positive elk herds in Colorado and a positive White-tailed deer herd in Wisconsin remain under State quarantine. All of the other 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. CWD also has been found in farmed elk in the Canadian provinces of Saskatchewan and Alberta. A retrospective study also showed that Mule deer exported from Denver to the Toronto Zoo in the 1980's were affected. For the band, see 1997 (band). ... Official language(s) English Capital Pierre Largest city Sioux Falls Area  Ranked 17th  - Total 77,116[1] sq mi (199,905 km²)  - Width 210 miles (340 km)  - Length 380 miles (610 km)  - % water 1. ... Binomial name Zimmermann, 1780 The White-tailed deer (Odocoileus virginianus), also known as the Virginia deer, or simply as the whitetail, is a medium-sized deer found throughout most of the continental United States, southern Canada, Mexico, Central America and northern portions of South America as far south as Peru. ... For other uses, see Oklahoma (disambiguation). ... Capital Saint Paul Largest city Minneapolis Largest metro area Minneapolis-St. ... This article is about the U.S. State. ... This article is about the state. ... For other uses see Quarantine (disambiguation) Quarantine is voluntary or compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. ... This article is about the Canadian province. ... For other uses, see Alberta (disambiguation). ... This article refers to the state capital of Colorado. ... The Toronto Zoo is a zoo located in the north eastern part of Toronto, Ontario, Canada. ...

Species that have been affected with CWD include elk, mule deer, white-tailed deer, black-tailed deer, and moose. Other ruminant species, including wild ruminants and domestic cattle, sheep, and goats, have been housed in wildlife facilities in direct or indirect contact with CWD-affected deer and elk with no evidence of disease transmission. There is ongoing research to further explore the possibility of transmission of CWD to other species. For other uses, see Elk (disambiguation). ... Binomial name (Rafinesque, 1817) The mule deer (Odocoileus hemionus) is a deer whose habitat is in the western half of North America. ... Binomial name Zimmermann, 1780 The White-tailed deer (Odocoileus virginianus), also known as the Virginia deer, or simply as the whitetail, is a medium-sized deer found throughout most of the continental United States, southern Canada, Mexico, Central America and northern portions of South America as far south as Peru. ... Trinomial name Odocoileus hemionus columbianus Richardson, 1829 Like all deer, black-tailed deer are herbivores. ... For other uses, see Moose (disambiguation). ... It has been suggested that this article or section be merged with Ruminantia. ... For general information about the genus, including other species of cattle, see Bos. ... Species See text. ... This article is about the domestic species. ...

References

The New York Times is a daily newspaper published in New York City and distributed internationally. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 277th day of the year (278th in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... April 8 is the 98th day of the year (99th in leap years) in the Gregorian calendar. ... The Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, is recognized as the leading United States agency for protecting the public health and safety of people. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... April 8 is the 98th day of the year (99th in leap years) in the Gregorian calendar. ... is the 260th day of the year (261st in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 139th day of the year (140th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 296th day of the year (297th in leap years) in the Gregorian calendar. ...

External links

• *This entry incorporates public domain text originally from the Animal and Plant Health Inspection Service, APHIS.
• Chronic Wasting Disease Alliance
• Chronic Wasting Disease (CWD) of Deer and Elk. Canadian Food Inspection Agency (2006-10-03). Retrieved on October 23, 2006.
• Elk Research Institute
• United States Geological Survey
• United States Department of Agriculture
• Colorado Division of Wildlife
• Illinois Department of Natural Resources
• Minnesota Department of Natural Resources
• Nebraska Game and Parks Commission
• New York State Department of Environmental Conservation
• Wisconsin Department of Natural Resources
• Wyoming Game and Fish
• Wildlife Disease Information Node Chronic Wasting Disease Factsheet and resources