Wednesday, August 05, 2009

Rate of CWD infection increases in core area WISCONSIN

Rate of CWD infection increases in core area

Weekly News Article Published: August 4, 2009 by the Central Office

MADISON – Testing of deer shot last year within the “core area” of chronic wasting disease (CWD) infection in southwest Wisconsin showed an increase in the rate of infection or disease prevalence.

Prevalence is the proportion of animals that test positive for CWD, the always fatal nervous system disease of white-tailed deer and other members of the cervid family.

In 2008, “estimates of prevalence (based on deer tested) in the South Central Wisconsin core area of infection showed increases in yearling and adult males,” said CWD project leader Davin Lopez.

The prevalence rate for adult bucks (2.5 years and older) in the western core area, which covers mostly western Dane County and eastern Iowa County, went from 10 percent in 2007 to 15.5 percent in 2008. The prevalence for yearling bucks went from 3 percent to 6 percent.

Recent studies of regional deer populations in Colorado and Wyoming -- states where CWD likely has infected wild deer for several decades -- are documenting high prevalence rates (20 to 40 percent) and lower survival of CWD-infected deer when compared to other deer in the populations. Authors of these studies suggest that CWD may be limiting deer numbers in these populations, according to Lopez.

“Five to ten years in the future, we will know better whether this was just a one year blip on the chart or the beginning of a trend of increasing disease prevalence in Wisconsin,” added population ecologist Robert Rolley.

Infection Rates

Epidemiological analyses of the prevalence data from the western core were conducted by Dennis Heisey of the U.S. Geological Survey-National Wildlife Health Center, Madison, and colleagues. Sophisticated statistical techniques that adjust for factors such as age and sex were used to estimate infection rates, more technically referred to as the force-of-infection.

They noted that the infection rates appear to show substantial random variability from one year to the next, but that there is evidence of a general underlying trend of increase at about 4 percent per year.

The statistical techniques also observed infection clusters and depended on age and sex. Their analyses suggested that the cause for the clustering is due primarily to when the disease arrives in an area.

Since 2002, DNR has analyzed almost 152,000 deer with a total of 1,172 free-ranging deer testing positive for CWD. All the positive deer were found within the CWD-MZ. Wisconsin has two separate epicenters of disease, one in the southwest part of the state, one in the southeast. The southeast CWD area is contiguous with a CWD area in northern Illinois where 256 CWD positive deer have been found since 2002.

In it for the Long Haul

“After seven years, it’s clear that there’s no easy answer to managing CWD, but we continue to believe that the stakes are high, it’s a statewide issue, and we take seriously our responsibility to manage the disease,” emphasized Lopez.

“We need to minimize the extent and spread of the disease in our treasured deer herd. Science tells us the only practical tool to do that is to reduce deer density and, therefore, deer to deer contact. To make that happen, everyone – DNR, landowners in the CWD zone, hunters, and people who cherish having robust, healthy wildlife in our state – needs to take a long term view of disease management,” he added.

CWD is an always fatal nervous system disease known to naturally infect white-tailed deer, mule deer, moose and elk. It belongs to the family of diseases known as transmissible spongiform encephalopathies (TSE) or prion diseases. Though it shares features with other prion diseases, like mad cow disease in cattle and scrapie in sheep, it is a distinct disease known to only affect members of the deer family. CWD has been discovered in wild deer or elk herds in 11 states and two Canadian provinces.

FOR MORE INFORMATION CONTACT: Davin Lopez, CWD Project Leader, Madison: 608-267-2948; Robert Rolley, Population Ecologist, Madison: 608-221-6341; Dennis Heisey, CWD Research Biologist, National Wildlife Health Center, Madison: 608-270-2478; Greg Matthews: (608)275-3317

Natural Resources Board to review plan for managing Chronic Wasting Disease in Wisconsin

Weekly News Article Published: August 4, 2009 by the Central Office

MADISON – A plan to manage chronic wasting disease (CWD) in Wisconsin will be presented to the state Natural Resources Board – the seven citizen member policy making body for the Department of Natural Resources – for consideration during its regular monthly meeting Aug. 12 in Hayward.

The plan asserts that without active disease management, the state will eventually experience lower deer populations and decreased opportunities to enjoy this valuable outdoor resource and Wisconsin’s state wildlife animal. CWD is always deadly to infected deer.

DNR’s goal over the next five years is to minimize the area of Wisconsin where CWD occurs and the number of infected deer in the state. The goal indicates a shift in the state’s management approach from attempting to eradicate the disease in the near term.

A Plan for Managing Chronic Wasting Disease in Wisconsin: The Next Five Years, a DNR product reviewed by citizens, stakeholders and conservation groups, notes that minimizing CWD “will require a commitment of human and financial resources over an extended period of time.” The plan reflects on seven years of CWD management in Wisconsin, and scientific and sociological challenges to managing the disease.

“Recent research shows a significant increase in the infection rate of bucks in the core CWD zone [see sidebar] – in that core zone, it appears one in eight adult bucks may have the disease. It is the consensus opinion of wildlife disease experts that without intervention, CWD will spread further in Wisconsin over time, and prevalence (the infection rate) of the disease will increase where the disease is currently found,” said Wildlife Director Tom Hauge.

The plan’s key strategies and measures are to:

Prevent New Introductions of CWD – stopping new disease establishment in wild deer herds is much less expensive and less damaging to the state than fighting diseases after they are established.

Respond to New Disease Foci – aggressively responding to newly discovered disease foci (locations) is the best option for disease control.

Control Distribution and Intensity of CWD – includes reducing deer herd in infected areas through hunting season structure and landowner permits as well as working with local citizens, the Conservation Congress and state Natural

Resources Board to conduct focused culling in areas of disease clusters along the edges of known CWD distribution.

Increase Public Recognition and Understanding of CWD Risks – it is important that Wisconsin’s citizens are kept informed of the latest scientific knowledge and recommendations for managing this disease.

Address the Needs of Our Customers – includes hunter deer testing, donating venison to food pantries, helping dispose of deer carcasses, monitoring for human prion diseases and examining potential risk to livestock.

Enhance the Scientific Information about CWD – conducting in-house research, directly funding university research and collaborating in studies conducted nationally and internationally.

“Control of CWD in a high density, free-ranging white-tailed deer population is unprecedented,” according to the plan, but DNR isn’t “willing to accept the eventual spread of chronic wasting disease across the state. CWD has the potential for significant impacts on the future of deer hunting in Wisconsin.”

CWD is a fatal nervous system disease known to naturally infect white-tailed deer, mule deer, moose and elk. It belongs to a group of fatal animal diseases known as transmissible spongiform encephalopathies, or TSE’s. Other TSE’s include scrapie in sheep, bovine spongiform encephalopathy (BSE or “mad cow disease”) in cattle, and Creutzfeldt-Jakob disease of humans. It was first identified in the Mt. Horeb area of Dane County in Feb. 2002.

FOR MORE INFORMATION CONTACT: Davin Lopez, CWD Project Leader, Madison: 608-267-2948; Greg Matthews: (608)275-3317.

CWD surveillance plan for 2009

Weekly News Article Published: August 4, 2009 by the Central Office

MADISON – State wildlife officials will again be sampling and testing hunter-harvested white-tailed deer this fall for chronic wasting disease (CWD). The sampling will be conducted primarily in the disease management zone of southern Wisconsin.

“Our goal is to monitor trends in disease prevalence and distribution patterns within the western monitoring area of western Dane and eastern Iowa counties and the eastern monitoring area in Rock and Walworth counties,” said Davin Lopez, CWD project leader for the Department of Natural Resources.

To that end, mandatory sampling of adult deer will take place in the western and eastern monitoring areas, and within an 84 square-mile area that encompasses Devil’s Lake State Park “where monitoring disease patterns is important to understanding disease dynamics,” noted Lopez.

Active surveillance using solicited but voluntary sampling will also be conducted along the northernmost known periphery of the disease in parts of Columbia, Crawford, Dane, Grant, Richland and Sauk counties.

Other surveillance goals include monitoring where and how many deer test positive for CWD at the edges of the known infected areas and at the borders of the CWD-Management Zone (CWD-MZ).

Besides the three locations where testing of adult deer is mandatory, DNR will focus sampling on the north and northwest quadrants of the CWD-MZ as part of its strategy to monitor along the disease periphery. DMU’s where hunters will be asked to submit deer for testing from selected townships include 73E-CWD, 71-CWD, 54B-CWD, 70-CWD, 70B-CWD, 70E-CWD, 70G-CWD and 76-CWD (see the above link to DNR’s web site).

Areas outside the CWD management zone are not scheduled for widespread CWD surveillance in 2009. Biologists and wildlife health officials will test car-killed deer and hunter-killed deer in a few small areas of Portage and Crawford counties near game farms that have had CWD positive deer in their herds. Testing of hunter-killed deer in these areas will be voluntary and locations of registration stations taking samples will be identified closer to the hunting season.

The CWD-MZ (pdf) covers all or parts of 18 counties and 22 deer management units (DMU) in southern Wisconsin.

Surveillance a Key Management Tool

Surveillance – the sampling and testing of deer – is one of the key components of DNR’s disease management strategy, according to agency biologists and researchers.

Wildlife biologists will also be asking for hunters to submit deer for sampling from an area around two deer farms outside of the CWD-MZ in Crawford and Portage Counties where positive captive deer have been found in the past.

Overall, DNR is planning to sample 8,250 adult deer in 2009. Through July 15, 2009, almost 152,000 free-ranging deer in Wisconsin have been analyzed for CWD with 1,173 testing positive for the disease. All positive deer were from within the current CWD-MZ.

FOR MORE INFORMATION CONTACT: Davin Lopez, CWD Project Leader, Madison: 608-267-2948; Greg Matthews: (608)275-3317

Tuesday, August 04, 2009

Susceptibilities of Nonhuman Primates to Chronic Wasting Disease

Thursday, July 23, 2009

UW Hospital warning 53 patients about possible exposure to rare brain disease


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