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From: TSS ()
Date: July 13, 2005 at 9:42 am PST


























CWD Positive Location

Herd Reduction Zone

Disease Eradication Zone


Chronic Wasting Disease


from the Wisconsin Department of Natural Resources March 2005

Wisconsin is wrapping up

its third season of CWD

management. Once again

landowners and hunters gave generously

of their time and talents to help

manage CWD in the state. We at the

Department of Natural Resources

(DNR) are so grateful for this help.

Strides are being made in managing

the disease but more work still needs

to be done. We are committed to

eradicating CWD in Wisconsin. It is

going to be a long-term process, and

a process that will continue to rely on

support and involvement from people

like you.

Surveillance continues to be a priority

in CWD management as we develop a

clear picture of the geographic extent

and prevalence of the disease. For the

2004-05 deer season, we concentrated

disease surveillance efforts in and

around the two DEZs, southeastern

Wisconsin, and in areas of CWDpositive

game farms. Over 18,000

deer have been sampled so far this

season. As of February 15, 2005, we

have received news of 99 positive

deer. A few positives were discovered

outside of the established DEZs. These

outlying positives will be taken into

consideration when deciding on CWD

management plans for next season.

Thanks to those who brought their

deer to a DNR collection station for

CWD sampling!

Data to date suggests that the western

DEZ and eastern DEZ are separate

disease events. Analysis of the geo-

Locations of CWD-Positive Deer in

Wisconsin and Illinois

Wisconsin data

updated 2/15/2005;

Illinois data updated


Researchers believe that the two areas of infection—one in the Dane-Iowa county

area and the other along the Wisconsin/Illinois border—may represent two separate

infection areas.

Continued on p. 2

graphic distribution of the western

DEZ outbreak shows that the pattern

of positives is not random, but is

tightly clustered. Although the western

DEZ is over 1,300-square miles

in size, more than 80 percent of the

positive deer are in a 126-square mile

area bounded by Spring Green, Mazomanie,

Black Earth, Mount Horeb,

and Ridgeway. Within this area of

concentrated disease, there is a core

of highest prevalence. A few sections

within this core had as high as 8 to

For more information on

chronic wasting disease, please


Click on "Chronic Wasting Disease

in Wisconsin."

2 Chronic Wasting Disease Update

12 percent of adult deer testing positive for


The eastern DEZ cases appear to be adjacent

to an outbreak in northeastern Illinois where

currently 75 CWD-positive deer have been

found since 2002. Surveillance data to date

indicates a more scattered pattern of disease

distribution in northern Illinois and southeast

Wisconsin, rather than the tight pattern of

disease distribution in the western DEZ. (See

map on front page for locations of CWD-positive


In addition to surveillance, herd reduction

remains a key component of CWD management.

For the 2004-05 season, we continued

to ask hunters to take as many deer off the

landscape as possible in an effort to drastically

reduce the herd size, and ultimately control

the spread of CWD. We heard from many

hunters that they wanted to help reduce the

herd, but taking more deer than can be used

goes against their hunting ethic. To address

the issue we funded a program where hunters

could donate DEZ deer to a food pantry. Over

1,800 deer have been donated by hunters to

the food pantry program. We also worked

with Valley of the Kings large-cat sanctuary

in Sharon, WI, to send hundreds of deer carcasses

not appropriate for the food pantry to

be used as lion food. Both options were well

received by hunters.

Please take the time to read the rest of this

newsletter for more updates on CWD in Wisconsin.

Additionally, more CWD information,

including the most up to date CWD surveillance

results, is available online at

Thank you once again for your interest

and help in managing CWD in Wisconsin!

Alan Crossley

CWD Project Leader

Farmed Cervid Update

The Department of Agriculture,

Trade, and Consumer Protection

(DATCP) regulates farm-raised

deer and elk in Wisconsin. There

are approximately 720 registered

deer and elk farms in the

state containing about 30,500

animals. The discovery of CWD

in Wisconsin has led to major

changes in the regulation of these

farmed deer and elk. Regulations


. It is no longer legal to accept

orphaned or injured deer from

the wild into farms or to fence

in property and capture wild


. Cervid farms must be enrolled

in the CWD monitoring

program to sell live animals.

The CWD monitoring program

requires an initial herd census

with offi cial individual animal

identifi cation and annual

reports accounting for where

every animal on the farm came

from or went in the past year.

About 550 herds are enrolled in

the monitoring program.

. All farms, whether enrolled in

the monitoring program or not

must CWD test every deer or elk

that is 16 months or older that

dies or goes to slaughter. More

than 10,000 farm-raised deer

and elk have been tested.

. Importation of deer and elk

into Wisconsin requires a

permit from the State

Veterinarian, a

certifi cate of


inspection, proof that they

are free of TB and brucellosis,

offi cial identifi cation

numbers on the animals, and

documentation that they come

from a herd with no evidence

of CWD in the past fi ve years.

This last requirement amounts

to a temporary moratorium

on many deer and elk imports

because most states did not

begin surveillance until


. Deer and elk farms are required

to meet fencing standards.

Producers are required to report

escapes within 48 hours. The

DNR has authority to kill

escaped farm-raised animals

if they are not immediately


As of January 2005, 27 farmraised

white-tailed deer and one

elk have tested positive for CWD

on seven farms. The latest was a

white-tailed deer on a Crawford

County farm. The herd was enrolled

in the CWD monitoring

program. The 19-month-old buck

was tested for CWD after it died

from respiratory causes.

Additionally, 20 herds are under

quarantine because they contain

animals that may have been

exposed to CWD. In some cases,

animals were bought from herds

later found to be infected with

CWD while others are within

Wisconsin’s wild deer CWD zones

and may have been exposed to

infected free-ranging deer.

For more information on CWD relating

to farmed deer, please visit

DATCP’s Web site at

CWD Update, Continued from p. 2

Chronic Wasting Disease Update 3


Research studies include topics such as:

. Deer dispersal, social behavior, and


. Disease ecology, including genetic

resistance of deer to the disease;

. Comparing Wisconsin CWD strains

to those found on other parts of the


. Spatial patterns and prevalence of CWD

in southwest and southeast Wisconsin;

. Transmission mechanisms, including

the effects of baiting and feeding and

between does and fawns before they are


. Dynamics of CWD prions in the soil;

. Susceptibility of other species, such as

cattle and scavengers, to CWD;

. Possible risks to human health,

including primate studies and

comparison of deer and human prion

genetic and molecular structures;

A comprehensive interagency CWD research

plan was developed in 2002 to determine

what was currently known about

CWD, CWD control strategies, and what

key information was needed to manage

the disease in Wisconsin. Compared to

many other diseases, relatively little was

known about CWD and effectiveness of

control strategies. Research priorities were

identifi ed in fi ve broad areas to increase

knowledge: disease ecology, deer ecology,

human ecology, diagnostics, and human

health implications of CWD.

Because of the need to implement the

disease control program quickly, an

adaptive management approach integrating

research and management activities

was identifi ed as a key component

of the CWD control strategy. By taking

this "learn-and-adapt" management

approach, we are able to incorporate

research and surveillance fi ndings into

management strategies as the information

becomes available.

In 2004, a total of 34 CWD research studies

were underway in Wisconsin. Another

12 studies were underway in other states

with which we are collaborating by providing

data and/or tissue samples. These

studies are being conducted and funded

by many partners such as University of

Wisconsin and the USGS National Wildlife

Health Center. Coordination of these

studies is being done by an interagency

team to insure research is focused on high

priority needs for managing CWD in Wisconsin,

to promote collaboration among

scientists, to facilitate data sharing, and

to promote joint problem solving.

. Attitudes, behavior, and desires of

hunters and landowners in relation to


. Analysis of deer removal efforts in

southwest Wisconsin and changes in

deer population size;

. Computer modeling to evaluate

alternate management strategies;

. Better diagnostic tools for detecting the


. Development of techniques to detect

CWD prion in the environment.

Information from these projects is being

used to evaluate the effectiveness of disease

control activities and in making management

decisions about future control strategies.

Research on diagnostic tests for CWD

has already resulted in the adoption of

screening tests that signifi cantly shorten

the time required to notify most hunters

of the status of their deer.

The following accounts give highlights

from a few of the CWD research efforts.

4 Chronic Wasting Disease Update

The Risk of CWD

Transmission with

Baiting and Feeding

Michael Samuel, Ph.D. and

Abbey Thompson

USGS Cooperative Wildlife Research Unit

University of Wisconsin-Madison

Tim VanDeelen, Ph.D

University of Wisconsin - Madison

Chris Yahnke

University of Wisconsin-Stevens Point

In this study the research team is

evaluating the role of supplemental

feeding in the direct and indirect

transmission of diseases like CWD in

white-tailed deer. They are using various

feeding techniques (trough, pile

and spread) and varying amounts of

corn at four supplemental feed stations

and two monitored natural feeding

areas within the fenced Sandhill

Wildlife Demonstration Area in Babcock,

Wisconsin. Disease transmission

rates are being estimated through

comparison of deer use, contact rates,

and fecal contamination at supplemental

feeding sites. Cameras are also

being used to capture information on

deer use and interactions occurring at

supplemental feeding sites and natural

feeding areas.

Biology and wildlife students at the

University of Wisconsin–Stevens Point

have been doing their part to quantify

CWD transmission risks associated

with baiting and feeding deer. They

compared 2.5-gallon versus 10-gallon

bait sites and piling the bait versus

spreading the bait over a larger area.

Using motion-sensing digital cameras,

the students, led by senior Casey

Wilke, found a signifi cantly higher

incidence of close deer-to-deer contact

at bait sites where the bait was piled

relative to sites where bait was broadcast.

Deer densities increased at all

bait sites relative to control sites where

only natural forage was available

The Dynamics of

CWD Prions in Soil

Joel Pedersen, Ph.D.

University of Wisconsin–Madison

Dr. Pedersen is trying to understand

what happens to CWD prions in soil.

This is important to understanding

the risks for environmental transmission

to deer and also to developing

practical and safe disposal practices.

Researchers are currently looking

at the persistence of prions and the

movement of prions through different

types of soil. They have found that

clay soils adsorb disease prions at a

much higher rate than sandy soils.

Researchers are using animal models

to estimate how long prions persist

in the soil and if infectivity declines

over time. They will also be exploring

what happens to prions in landfi ll and

wastewater systems.

Genetic Resistance

to CWD in

White-tailed Deer

Judd Aiken, Ph.D.

School of Veterinary Science

University of Wisconsin–Madison

Researchers are investigating whether

there is genetic CWD resistance in

deer by comparing CWD-infected and

non-infected wild deer. Conclusions

indicate that there is variability in

prion proteins among Wisconsin deer

and that at least 95 percent of Wisconsin

deer have genotypes known

to be genetically susceptible to CWD.

These results suggest that virtually

all Wisconsin deer are susceptible to

CWD and would not be genetically

resistant to the disease.

Chronic Wasting Disease Update 5


Dimensions Research

Jordan Petchenik, M.S.

Wisconsin Department of Natural Resources

Human dimensions researchers surveyed

hunters statewide in 2002, DEZ

hunters in 2003 and landowners in

the DEZ in 2004 to determine attitudes

towards CWD management, hunting

behavior in response to CWD,

their assessment of health risks, and

likelihood of future hunting participation.

Landowners and hunters are key

components to CWD management.

Their feelings and attitudes are very

important to understand and should

be carefully considered in making

management and communication


Wisconsin also is a participant in an

eight-state study of hunters’ responses

to CWD. The Western Association

of Fish and Wildlife Agencies is organizing

the study which will allow

comparison across states with an

emphasis on learning how CWD has

affected, if at all, hunting experiences,

and how future hunts may be affected

if conditions changed or CWD spread

to new areas.

2003 Report on Hunter

Effort and Attitudes

Robert Holsman, Ph.D. and

Ryan D. Meinerz

University of Wisconsin–Stevens Point

In an effort to better understand

hunter behavior in the western DEZ,

UW-Stevens Point researchers Holsman

and Meinerz mailed diary cards

over a three month period to 2,000

hunters in southern Wisconsin to

measure the amount of time they

spent in the fi eld.

The project is funded by the DNR and

UW-Stevens Point. It is an effort to be

responsive to hunter opinions and is

one part of the DNR’s learn-and-adapt

disease management plan.

The preliminary results show that

most gun deer hunters in the western

DEZ give the DNR a "B" or better

grade in their handling of the management,

despite the sacrifi ces hunters

have been asked to make to help

eliminate the disease. Survey results

also show widespread support for the

baiting and feeding bans.

These preliminary results provide

baseline data by which to compare

this and future fall gun deer hunts.

The study will track over the next

few years how hunter attitudes vary

as agency management does or does

not change within the DEZs.

The second year of the study is well

underway, collecting and analyzing

information related to signifi cant social

and psychological variables that

predict public concern about CWD

and support of control strategies put

in place by the DNR.

Human Prion

Disease Surveillance

James Kazmierczak, DVM

Department of Health and Family Services

Creutzfeldt-Jakob disease (CJD) is

a TSE that affects humans. First described

in the 1920s, CJD occurs sporadically

worldwide at a rate of about

one case per million population. The

Wisconsin Division of Public Health

maintains an ongoing surveillance

for CJD, consisting of case-reporting

by neurologists and hospital infection

control practitioners, as well as

reviews of death certifi cates. Suspected

cases are investigated, and whenever

possible, are confi rmed by autopsy.

From 1997 to date, there have been

17 autopsy-confi rmed cases and 20

possible/probable cases reported

through this surveillance. All of the

confi rmed cases are consistent with

the sporadic or familial form of CJD,

and do not have the characteristics of

variant CJD, the form of the disease

seen in Europe associated with bovine

spongiform encephalopathy ("mad

cow disease"). The average annual

incidence of reported CJD in Wisconsin,

including confi rmed, probable,

and possible cases, is approximately

one per million.




Department of Natural Resources

Bureau of Wildlife Managment

101 S. Webster Street

PO Box 7921

Madison, WI 53707-7921

Presorted Standard

U.S. Postage


Madison, WI

Permit 906

Are You Getting More than One Newsletter?

If you receive more than one of these newsletters each month, please

clip off the labels from each of the newsletters and send them back to

us so we can remove doubles from our mailing list: CWD Information,

Wisconsin DNR WM/6, PO Box 7921, Madison, WI 53707.

For more information on

CWD visit the following

Web sites:

and click on "Chronic Wasting

Disease in Wisconsin,"





or call the DNR’s toll-free

CWD information line

1-877-WISC CWD or


between 8 A.M.–4 P.M.


What should I do if I observe or harvest a deer

that I suspect might have CWD?

Call the local DNR offi ce right away.

The DNR will make every effort to collect samples

from the possibly affected deer for CWD testing.

Wisconsin State Agency Contacts

Department of Natural


Bureau of Wildlife



Department of

Agriculture, Trade and

Consumer Protection

Offi ce of Outreach and

Policy/Animal Health

and Safety Issues

608-224-5130 keyword:

chronic wasting disease

Department of Health

and Family Services



The Wisconsin Department of Natural Re sourc es

pro vides equal opportunity in its employment, pro-

grams, services and func tions under an Affi rmative

Action Plan. If you have any questions, please write to

Equal Opportunity Offi ce, Department of the Interior,

Wash ing ton, D.C. 20240.

This publication is available in

alternate format (large print,

Braille, audio tape, etc.) upon

request. Please call 608-266-

8204 for more information.


Does CWD pose a threat to human health?

James Kazmierczak, Epidemiologist, Wisconsin Department of Health

Hi, I'm Jim Kazmierczak. I'm with the state division of public health.

The single issue that I am going to try to address today is the issue of whether chronic wasting

disease poses any risk to human health. As you probably already heard earlier in the

presentation, chronic wasting disease belongs to a family of related diseases called transmissible

spongiform encephalopathies, or TSE's for short. These diseases are related in the sense that

they're all caused by this infectious protein that we call a prion, and also they're related in the fact

affected the all present the same sort of clinical disease as a result of the type of lesions that they

produce in the brain.

We know that different diseases in this family called TSE's, affect different species. For instance,

we have disease called scrapie that affects sheep and goats. We have a particular kind of prion

that affects mink. We have the bovine spongiform encephalopathy that's been in the news a lot,

the Mad Cow Disease that affects obviously bovines. We have chronic wasting disease that

affects deer and elk. And actually humans have their own unique type of spongiform

encephalopathy. That disease is called Creutzfeldt-Jakob Disease, or CJD. This is the disease

of humans that is similar, it's in the same group or family, as the other TSE's that we just


I want to talk a bit about Creutzfeldt-Jakob Disease in humans. I feel I need to cover this

because first of all, it's logical to assume that any prion disease that may in fact across the

species barrier to humans, will result in a similar type of disease as Creutzfeldt-Jakob Disease.

Also, you're going to need to know a little bit about Creutzfeldt-Jakob Disease and in order to

understand some of the points I'll make when I talk about the potential risk of chronic wasting

disease to humans.

Creutzfeldt-Jakob Disease is a nasty disease. It produces progressive dementia, confusion, lack

of coordination, and eventually death. This is an invariably fatal disease, and it usually kills its

victims within twelve months of onset. The incubation period of this disease-- that is, the time

between when one becomes exposed to the infectious protein, and when one actually develops

symptoms, can be very variable, and it can range from between 15 months to over 20 years. So

it can have an extraordinarily long incubation period.

As far as how Creutzfeldt-Jakob Disease is diagnosed in humans, the first thing you need to

know is that there is no test that can be applied to show that someone is in the incubation phase

of CJD. It's not until clinical signs appear that the disease can start to be diagnosed, and at that

point the diagnosis is based on clinical signs and symptoms, laboratory tests,

electroencephalogram patterns, and the definitive diagnosis is then made by actually looking at

sections of the brain microscopically either with a brain biopsy or with a post-mortem


I'm going to add another wrinkle to this. We've been looking at CJD or Creutzfeldt-Jakob Disease

until now as a single entity-- when in fact one could split CJD into two different forms. The first is

what we call classic Creutzfeldt-Jakob Disease. This form of the disease has been known to

occur for at least 70 years, and it was probably occurring long before that. So this is not a new

disease. It affects primarily older people. The vast majority of people to do get this disease are

over the age of 65, and it affects people worldwide at a rate of approximately one case per million

people. And that rate holds true here in the United States, including in Wisconsin.

How does one acquire this classic form of Creutzfeldt-Jakob Disease? In many cases it's just not

known with certainty; although there are some mechanisms that are well-known. The majority of

cases do appear to occur spontaneously for no apparent reason. There are, however, a

percentage of cases that apparently are familial; in other words, there is a family history of this, so

there is a genetic component to a certain percentage of these cases, and interviewing patient

families we can find a family history of this. It is also possible to acquire CJD through certain

medical procedures; procedures that involve the transfer of tissues or tissue extracts from an

infected patient (although obviously it's unknown to the medical providers at the time that the

person was infected). But it can be transmitted, for instance, to people who receive pituitary

extract; or certain brain covering tissue that is used for transplants. The infectious agent can be

transmitted from the sick individuals to the well individuals by these sorts of medical procedures.

And finally there's a small number of people who actually have developed this from ingestion.

You may think that's an odd way of acquiring it, but this was discovered upon study of a

Creutzfeldt-Jakob-like disease among some New Guinea tribesmen back several decades ago.

At that time they were still practicing some ritualistic cannibalistic practices, and that's how we

know the disease can also be transmitted by ingestion.

So that's sort of a summary of the classic form of Creutzfeldt-Jakob Disease. Again this is the

form of disease has been known to occur for decades, and has been occurring worldwide at a

rate of approximately one per million people. Now, what's new on the scene is a form of the

disease called new variant Creutzfeldt-Jakob Disease, or new variant CJD. This form of the

disease was first seen in England only about six years ago, and it is still limited to the United

Kingdom and some European countries. It has not been found in the United States. New variant

CJD is quite similar to the classic form that we've just finished talking, about it does tend to occur

in younger people-- people with an average age in their thirties, actually-- and it differs in some

ways-- subtly, though-- from the classic CJD in clinical signs. For instance, a neurologist would

normally be able to differentiate on a clinical basis and some laboratory work, whether one has

the classic form, or one has this new variant form of CJD. There's also enough difference in the

microscopic appearance of brain tissue, so the bottom line is that the two types of disease-- the

classic and the new variant forms-- can be differentiated.

So why has this new variant of Creutzfeldt-Jakob Disease appeared on the scene, seemingly of

nowhere? Well, most of you probably know that during the 1980s there was an epidemic of

bovine spongiform encephalopathy (better known as Mad Cow Disease) that occurred in Great

Britain. It certainly got tons of media coverage at the time. Hundreds of thousands of cattle at

that time were infected, many of which eventually found their way into the human food chain. The

best evidence suggests that the prion that causes the bovine encephalopathy somehow managed

to jump the species barrier and affect humans. Apparently when this prion did manage to infect a

different species (in other words did manage to get in to humans), it produced a different clinical

picture than the classic form of CJD.

By now you're probably wondering, "So what?" Now that we know the background about this

disease form in humans, let's go back to the original question about the potential for chronic

wasting disease to affect human beings. First of all, as far as we know there's never been the

case of new variant Creutzfeldt-Jakob Disease here in this country-- and people have looked.

The Centers for Disease Control began looking for the new variant form of Creutzfeldt-Jakob

Disease several years ago. What they're doing is looking at people with compatible symptoms to

Creutzfeldt-Jakob Disease who are under the age of 55. If you recall, I said that this disease

tends to occur mostly in younger people, so onset at a young age would be a tip-off that we may

be seeing this new variant form of Creutzfeldt-Jakob Disease.

The other bit of information that is somewhat reassuring as far as looking at the human health

potential of chronic wasting disease, is that the classic form of CJD which does occur in this

country, does not occur at any increased rates in the states out west that have had chronic

wasting disease in their deer and elk herd for decades. Those states are not seeing any increase

in Creutzfeldt-Jakob Disease, compared to states that don't have this disease in their deer herds.

Furthermore, both the World Health Organization and the Centers for Disease Control state that

there's no scientific evidence to prove any sort of link between chronic wasting disease and any

human health affects. And finally, researchers have never been able to demonstrate infectivity of

muscle tissue, whether that's from CWD infected deer or elk, or BSE infected cattle, they've never

been able to show that muscle tissues actually is infective as far as transmitting this disease.

So those are all fairly reassuring points, but-- as we mentioned earlier it appears that at least

once in the past, a prion disease has been able to jump the species barrier and affect humans.

This is what happened in Great Britain with the Mad Cow problem. And in a study that was just

recently published, mice that were injected with a strain of the prion protein that was actually

adapted to grow in rodents, they found that when they infected these mice they were actually able

to transfer the infection by way of their skeletal muscle. So at least under these laboratory

conditions, skeletal muscle can be infectious in those circumstances. Whether that's truely

relatable to what happens in the real world, frankly we just aren't sure. So can one say with

certainty that chronic wasting disease will never cause human disease? Unfortunately, not. None

of us has a crystal ball, and its actually very difficult, as you might expect, to be able to prove a

negative-- to prove that CWD will never affect humans. I do think that if there is any risk-- and I

said if-- it's likely to be quite low, based on the fact that first of all chronic wasting disease has

never been known to affect humans, and also based on what we know about the epidemic of

BSE in England and the new variant form of CJD in humans there. Here we are about a decade

and a half after the outbreak in cattle, and even today there's only approximately 120 cases in all

of Europe of the new variant Creutzfeldt-Jakob Disease. So that's fairly reassuring. I do wish I

could quantify this risk in some way and try to put it in some perspective-- like perhaps comparing

it to, say, the risk of cigarette smoking or the risk of drinking and driving. But it's impossible to try

to quantify an event that's never occurred-- and again, CWD has never been known to result in

human illness. As far as anyone knows, this is strictly a disease of deer and elk.

Finally, the question is, "Is it safe to eat venison from deer that are harvested from this area?"

Even though there is no evidence that CWD has ever caused human disease, because of the

uncertainty about how it's transmitted, experts in the World Health Organization do advise that no

part of any deer or elk that's known to be infected with CWD, be consumed by people. It also

suggests that people avoid consuming certain tissues of any deer or elk-- and that would include

tissues like brain, spinal cord, eyes, spleen, tonsils and lymph nodes-- because that's where the

prion tends to congregate, in those tissues. So although the World Health Organization does

state that there's never been any scientific evidence to demonstrate that CWD can cause illness

in humans, they do recommend not eating any venison from known infected deer. So are they

hedging their bets? Well, sure they are-- even though the scientific evidence so far does not

indicate a risk, no one can give you that absolute guarantee of future safety. The best that I could

do is to try to accurately convey to you what's known about the potential risk, and then let each

person decide how comfortable he or she is with that small degree of uncertainty about the safety

of venison. Unfortunately there just are no easy answers.


Chronic Wasting Disease and Potential Transmission to Humans
Ermias D. Belay,* Ryan A. Maddox,* Elizabeth S. Williams,† Michael W. Miller,‡ Pierluigi Gambetti,§ and Lawrence B. Schonberger*
*Centers for Disease Control and Prevention, Atlanta, Georgia, USA; †University of Wyoming, Laramie, Wyoming, USA; ‡Colorado Division of Wildlife, Fort Collins, Colorado, USA; and §Case Western Reserve University, Cleveland, Ohio, USA

Suggested citation for this article: Belay ED, Maddox RA, Williams ES, Miller MW, Gambetti P, Schonberger LB. Chronic wasting disease and potential transmission to humans. Emerg Infect Dis [serial on the Internet]. 2004 Jun [date cited]. Available from:


Chronic wasting disease (CWD) of deer and elk is endemic in a tri-corner area of Colorado, Wyoming, and Nebraska, and new foci of CWD have been detected in other parts of the United States. Although detection in some areas may be related to increased surveillance, introduction of CWD due to translocation or natural migration of animals may account for some new foci of infection. Increasing spread of CWD has raised concerns about the potential for increasing human exposure to the CWD agent. The foodborne transmission of bovine spongiform encephalopathy to humans indicates that the species barrier may not completely protect humans from animal prion diseases. Conversion of human prion protein by CWD-associated prions has been demonstrated in an in vitro cell-free experiment, but limited investigations have not identified strong evidence for CWD transmission to humans. More epidemiologic and laboratory studies are needed to monitor the possibility of such transmissions.


The lack of evidence of a link between CWD transmission and unusual cases of CJD, despite several epidemiologic investigations, and the absence of an increase in CJD incidence in Colorado and Wyoming suggest that the risk, if any, of transmission of CWD to humans is low. Although the in vitro studies indicating inefficient conversion of human prion protein by CWD-associated prions raise the possibility of low-level transmission of CWD to humans, no human cases of prion disease with strong evidence of a link with CWD have been identified. However, the transmission of BSE to humans and the resulting vCJD indicate that, provided sufficient exposure, the species barrier may not completely protect humans from animal prion diseases. Because CWD has occurred in a limited geographic area for decades, an adequate number of people may not have been exposed to the CWD agent to result in a clinically recognizable human disease. The level and frequency of human exposure to the CWD agent may increase with the spread of CWD in the United States. Because the number of studies seeking evidence for CWD transmission to humans is limited, more epidemiologic and laboratory studies should be conducted to monitor the possibility of such transmissions. Studies involving transgenic mice expressing human and cervid prion protein are in progress to further assess the potential for the CWD agent to cause human disease. Epidemiologic studies have also been initiated to identify human cases of prion disease among persons with an increased risk for exposure to potentially CWD-infected deer or elk meat (47). If such cases are identified, laboratory data showing similarities of the etiologic agent to that of the CWD agent would strengthen the conclusion for a causal link. Surveillance for human prion diseases, particularly in areas where CWD has been detected, remains important to effectively monitor the possible transmission of CWD to humans. Because of the long incubation period associated with prion diseases, convincing negative results from epidemiologic and experimental laboratory studies would likely require years of follow-up. In the meantime, to minimize the risk for exposure to the CWD agent, hunters should consult with their state wildlife agencies to identify areas where CWD occurs and continue to follow advice provided by public health and wildlife agencies. Hunters should avoid eating meat from deer and elk that look sick or test positive for CWD. They should wear gloves when field-dressing carcasses, bone-out the meat from the animal, and minimize handling of brain and spinal cord tissues. As a precaution, hunters should avoid eating deer and elk tissues known to harbor the CWD agent (e.g., brain, spinal cord, eyes, spleen, tonsils, lymph nodes) from areas where CWD has been identified.



Bovine Spongiform Encephalopathy, Chronic Wasting Disease, Scrapie, and the Threat to Humans from Prion Disease Epizootics
Patrick J Bosque MD
Division of Neurology, 700 Delaware Street MC 4000, Denver Health Medical Center, Denver, CO, 80204-4507, USA

Current Neurology and Neuroscience Reports 2002, 2:488-495

Published 1 November 2002


Ongoing endemics and epidemics of prion disease afflict several species of ruminants regularly consumed by humans. Bovine spongiform encephalopathy (BSE) is epidemic in British cattle, and is now found in the cattle of more than 20 countries. A large, and apparently growing, epidemic of chronic wasting disease plagues deer and elk in North America. Finally, scrapie has been endemic in the sheep of most countries for many decades. It was once assumed that humans were not susceptible to these ruminant forms of prion disease, but an outbreak of a new form of Creutzfeldt-Jakob disease (CJD) among young Britons, almost certainly due to dietary exposure to BSE-contaminated beef, has disproved this supposition. Although all prion diseases share the same fundamental pathologic mechanism, transmission between species is sometimes inefficient. The basis of this "species barrier" is incompletely understood, but interspecies differences in the amino acid sequence of the prion protein and the strain of prions involved play critical roles. Reliable experimental models for determining the resistance of humans to animal prion diseases do not yet exist. It is possible that animal to human transmission of prion disease may manifest as CJD with unusual characteristics, but this is not necessarily the case. In the absence of a reliable means for determining the susceptibility of humans to animal prion disease, measures to minimize human exposure to animal prions should be emphasized.

-------- Original Message -------- Subject: DOCKET-- 03D-0186 -- FDA Issues Draft Guidance on Use of Material From Deer and Elk in Animal Feed; Availability
Date: Fri, 16 May 2003 11:47:37 -0500
From: "Terry S. Singeltary Sr."

Greetings FDA,i would kindly like to comment on;Docket 03D-0186FDA Issues Draft Guidance on Use of Material From Deer and Elk in Animal Feed; AvailabilitySeveral factors on this apparent voluntary proposal disturbs me greatly,please allow me to point them out;1. MY first point is the failure of the partial ruminant-to-ruminant feedban of 8/4/97. this partial and voluntary feed ban of some ruminantmaterials being fed back to cattle is terribly flawed. without the_total_ and _mandatory_ ban of all ruminant materials being fedback to ruminants including cattle, sheep, goat, deer, elk and mink,chickens, fish (all farmed animals for human/animal consumption),this half ass measure will fail terribly, as in the past decades... 2. WHAT about sub-clinical TSE in deer and elk? with the recentfindings of deer fawns being infected with CWD, how many couldpossibly be sub-clinically infected. until we have a rapid TSE test toassure us that all deer/elk are free of disease (clinical and sub-clinical),we must ban not only documented CWD infected deer/elk, but healthyones as well. it this is not done, they system will fail...3. WE must ban not only CNS (SRMs specified risk materials),but ALL tissues. recent new and old findings support infectivityin the rump or ass muscle. wether it be low or high, accumulationwill play a crucial role in TSEs.4. THERE are and have been for some time many TSEs in theUSA. TME in mink, Scrapie in Sheep and Goats, and unidentifiedTSE in USA cattle. all this has been proven, but the TSE in USAcattle has been totally ignored for decades. i will document thisdata below in my references.5. UNTIL we ban all ruminant by-products from being fed backto ALL ruminants, until we rapid TSE test (not only deer/elk) butcattle in sufficient numbers to find (1 million rapid TSE test inUSA cattle annually for 5 years), any partial measures such as theones proposed while ignoring sub-clinical TSEs and not rapid TSEtesting cattle, not closing down feed mills that continue to violate theFDA's BSE feed regulation (21 CFR 589.2000) and not makingfreely available those violations, will only continue to spread theseTSE mad cow agents in the USA. I am curious what we willcall a phenotype in a species that is mixed with who knowshow many strains of scrapie, who knows what strain or how manystrains of TSE in USA cattle, and the CWD in deer and elk (notelling how many strains there), but all of this has been renderedfor animal feeds in the USA for decades. it will get interesting oncesomeone starts looking in all species, including humans here in theUSA, but this has yet to happen... 6. IT is paramount that CJD be made reportable in every state(especially ''sporadic'' cjd), and that a CJD Questionnaire mustbe issued to every family of a victim of TSE. only checking deathcertificates will not be sufficient. this has been proven as well(see below HISTORY OF CJD -- CJD QUESTIONNAIRE)7. WE must learn from our past mistakes, not continue to makethe same mistakes... REFERENCES


Oral transmission and early lymphoid tropism of chronic wasting disease
PrPres in mule deer fawns (Odocoileus hemionus )
Christina J. Sigurdson1, Elizabeth S. Williams2, Michael W. Miller3,
Terry R. Spraker1,4, Katherine I. O'Rourke5 and Edward A. Hoover1

Department of Pathology, College of Veterinary Medicine and Biomedical
Sciences, Colorado State University, Fort Collins, CO 80523- 1671, USA1
Department of Veterinary Sciences, University of Wyoming, 1174 Snowy
Range Road, University of Wyoming, Laramie, WY 82070, USA 2
Colorado Division of Wildlife, Wildlife Research Center, 317 West
Prospect Road, Fort Collins, CO 80526-2097, USA3
Colorado State University Veterinary Diagnostic Laboratory, 300 West
Drake Road, Fort Collins, CO 80523-1671, USA4
Animal Disease Research Unit, Agricultural Research Service, US
Department of Agriculture, 337 Bustad Hall, Washington State University,
Pullman, WA 99164-7030, USA5

Author for correspondence: Edward Hoover.Fax +1 970 491 0523. e-mail

Mule deer fawns (Odocoileus hemionus) were inoculated orally with a
brain homogenate prepared from mule deer with naturally occurring
chronic wasting disease (CWD), a prion-induced transmissible spongiform
encephalopathy. Fawns were necropsied and examined for PrP res, the
abnormal prion protein isoform, at 10, 42, 53, 77, 78 and 80 days
post-inoculation (p.i.) using an immunohistochemistry assay modified to
enhance sensitivity. PrPres was detected in alimentary-tract-associated
lymphoid tissues (one or more of the following: retropharyngeal lymph
node, tonsil, Peyer's patch and ileocaecal lymph node) as early as 42
days p.i. and in all fawns examined thereafter (53 to 80 days p.i.). No
PrPres staining was detected in lymphoid tissue of three control fawns
receiving a control brain inoculum, nor was PrPres detectable in neural
tissue of any fawn. PrPres-specific staining was markedly enhanced by
sequential tissue treatment with formic acid, proteinase K and hydrated
autoclaving prior to immunohistochemical staining with monoclonal
antibody F89/160.1.5. These results indicate that CWD PrP res can be
detected in lymphoid tissues draining the alimentary tract within a few
weeks after oral exposure to infectious prions and may reflect the
initial pathway of CWD infection in deer. The rapid infection of deer
fawns following exposure by the most plausible natural route is
consistent with the efficient horizontal transmission of CWD in nature
and enables accelerated studies of transmission and pathogenesis in the
native species.


These results indicate that mule deer fawns develop detectable PrP res
after oral exposure to an inoculum containing CWD prions. In the
earliest post-exposure period, CWD PrPres was traced to the lymphoid
tissues draining the oral and intestinal mucosa (i.e. the
retropharyngeal lymph nodes, tonsil, ileal Peyer's patches and
ileocaecal lymph nodes), which probably received the highest initial
exposure to the inoculum. Hadlow et al. (1982) demonstrated scrapie
agent in the tonsil, retropharyngeal and mesenteric lymph nodes, ileum
and spleen in a 10-month-old naturally infected lamb by mouse bioassay.
Eight of nine sheep had infectivity in the retropharyngeal lymph node.
He concluded that the tissue distribution suggested primary infection
via the gastrointestinal tract. The tissue distribution of PrPres in the
early stages of infection in the fawns is strikingly similar to that
seen in naturally infected sheep with scrapie. These findings support
oral exposure as a natural route of CWD infection in deer and support
oral inoculation as a reasonable exposure route for experimental studies
of CWD.



full text;

Guidance for Industry: Use of Material From Deer and Elk In Animal Feed

Terry S. Singeltary Sr.
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