Wildlife Diseases of Concern for Minnesota’s Deer Populations Michelle Carstensen, Ph.D Wildlife...
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Concern for Minnesota’s Deer Populations Michelle Carstensen, Ph.D Wildlife Health Program Supervisor MN DNR, Division of Wildlife
Wildlife Diseases of Concern for Minnesota’s Deer Populations Michelle Carstensen, Ph.D Wildlife Health Program Supervisor MN DNR, Division of Wildlife
Wildlife Diseases of Concern for Minnesotas Deer Populations
Michelle Carstensen, Ph.D Wildlife Health Program Supervisor MN
DNR, Division of Wildlife
Slide 3
Why do wildlife get diseases? Exposure to a wide variety of
pathogens Viruses Bacteria Parasites Interactions with domestic
livestock Social behavior Artificial baiting and feeding
Nutritional stress and winter severity
Slide 4
What is Chronic Wasting Disease? CWD is a slowly progressive,
brain disease of deer, elk, and moose CWD belongs to the family of
diseases known as transmissible spongiform encephalopathies (TSE)
or prion diseases Other TSEs include scrapie (sheep), BSE (cattle),
Jakob- Creutzfeldt (humans) Photo by Terry Kreeger
Slide 5
What Does the Name Mean? Transmissible Can be spread from
animal to animal Spongiform sponge-like (full of holes)
Encephalopathy brain disease Photo: Chronic Wasting Disease,
courtesy of CO State University College of Veterinary Medicine
& Biomedical Sciences
Slide 6
Understanding the TSE Agent Not caused by a virus, fungus, or
bacteria Disease is transmitted by a misshapen host protein, called
a prion
Slide 7
Characteristics of all TSEs, including CWD Neurologic clinical
signs: dementia, incoordination, excessive salivation, abnormal
behavior, etc. No treatment, always fatal No host immune response,
thus no easy vaccine or diagnostics for live animals Difficult to
inactivate infectivity Unconventional infectious agent Spread
animal-to-animal; persists in the environment
Slide 8
What we know about CWD Spread animal-to-animal (saliva, feces,
urine) Early detection looks for prion accumulation in the
retropharyngial lymph nodes and obex portion of brain Average 16
months or more (up to 3 yrs) from exposure to clinical disease
Prions remain infectious in environment (soil) for years Only known
in cervids; no evidence of transmission to other wild mammals or
humans Photo by Terry Kreeger
Slide 9
Slide 10
CWD Surveillance in Minnesota Risk-Based Surveillance 2005 To
Present Based On Suspect- deer exhibiting CWD symptoms New
infection found in adjacent state- done several times for WI
infections Association with positive captive cervid farm- Conduct
surveillance around areas known to have CWD (n=5) 5 CWD-positive
cervid farms in MN
Slide 11
Slide 12
An Outbreak of Bovine Tuberculosis in Minnesotas Wild Deer in
NW MN
Slide 13
The Disease.. Bovine tuberculosis (TB) is an infectious disease
that is caused by the bacterium Mycobacterium bovis (M. bovis).
Bovine TB primarily affects cattle, however, other animals may
become infected. Detected in beef cattle in NW MN in 2005, total of
12 herds were infected MN lost its federal TB-Free status in 2006
Significance? Trade & economic losses are severe where
infection is discovered
Slide 14
Close-up of infected lungs Pus-filled nodules on lungs of a
deer infected with bovine TB
Slide 15
Thief Lake WMA
Slide 16
How is MNDNR Managing Bovine TB in Deer? Reduce deer densities
Special hunts, sharpshooting, landowner shooting permits, aerial
gunning Restrict recreational feeding of deer Ban recreational
feeding Address risk mitigation at the cattle-deer interface
Deer-proof fencing program Change farming practices to reduce
risk
Slide 17
Other Diseases Occurring in Deer
Slide 18
Epizootic Hemorrhagic Disease An acute, infectious, often fatal
viral disease of some wild ruminants. Characterized by extensive
hemorrhages, has been responsible for significant die-off of deer
in other states Transmitted by a biting fly or gnat Death is
sudden
Slide 19
Epizootic Hemorrhagic Disease South Dakota estimated that over
3000 deer died of EHD in 2012 Disease showed up in August as deer
sought water and shade as the fever and other symptoms showed up.
Can also infect other animals but effect is not as severe It is not
considered a threat to humans
Slide 20
Parasites of Deer the Hunter may Encounter Liver Flukes Ticks
& Mites Bot Fly Larvae
Slide 21
Liver flukes are a large trematode (flatworm
Slide 22
Liver flukes normal definitive host is the white-tailed deer.
Moose, cattle, mule deer, sheep, and cattle can also be infected
and are dead end- hosts for flukes Dead-end hosts mean they cant
complete their life cycle in these hosts An aquatic snail is
required to complete the life cycle Generally do not cause illness
in deer but can cause harmful secondary infections
Slide 23
Slide 24
The female fly while in flight ejects minute larvae into the
nostrils of the host deer. Larvae become attached in clusters and
develop at the base of the deers tongue Are expelled by deer when
larvae are fully developed Signs in deer may be snorting
Slide 25
Skin Diseases Mange (mites) Dermatophilosis (bacterial) Other
hair loss
Slide 26
Cutaneous Fibromas Warts caused by a virus
Slide 27
Seromas Fluid-filled cyst, typically associated with
pucture-type injuries
Slide 28
What Preventive Measures Should Hunters Take? Do not shoot,
handle or consume a deer that is acting abnormally or appears to be
sick. When field-dressing game, wear rubber gloves and minimize the
use of a bone saw to cut through the brain or spinal cord
(backbone). Bone out the meat. Minimize contact with and do not
consume brain or spinal cord tissues, eyes, spleen, or lymph nodes.
Always wash hands thoroughly after dressing and processing game
meat. Cook meat to 165 degrees F.