Transcript Slide 1

Diseases & Causative Agents
• Infectious Diseases
– Viral
– Prion
– Bacterial
– Protozoal
– Parasitic
Diseases & Causative Agents
• Non-Infectious Diseases
– Chemical
(pesticide, heavy metals, contaminants)
– Physiological
– Genetic
– Nutritional
– Trauma
H
A
A
H
Ex: Influenza
Agent Increased
E
Good Health
“In Balance”
A
H
Ex: Tularemia, Plague
Host pop. increased
H
A
H
Ex: Air Pollution
-Environment upset &
makes host more
susceptible
A
Ex: Flood
-Environment upset &
promotes growth of agent
(typhoid fever, cholera)
Diseases & Causative Agents
• Disease Transmission
– Direct: usually within spp.
– Indirect: through different spp.
Diseases & Causative Agents
• Contagious – transmittable to others
– All contagious diseases are infectious
Contagious
cold
Infectious (not contagious)
tetanus
Diseases & Causative Agents
• Chronic: slow-acting to overcome
resistance of host (long-term)
• Acute: short-term, agent overwhelms host
rapidly
• Subclinical: don’t develop clinical signs of
disease
Diseases & Causative Agents
• Pathogenic: ability of agent to induce disease
• Virulence: severity of disease produced by
agent
e.g., common cold very pathogenic, not virulent
rabies = not very pathogenic, very virulent
Wildlife Diseases
• Interest from wildlife
management point-ofview:
– Domestic and/or wild
animals can serve as
reservoirs and/or
vectors
– Density of wildlife
populations
Wildlife Diseases
• Interest from human
health & safety pointof-view:
– Domestic and/or wild
animals can serve as
reservoirs and/or
vectors
 e.g., avian influenza
 Since 2003, 393
human cases, 248
deaths (WHO)
Wildlife Diseases
• Interest from
pet/domestic animal
health & safety pointof-view:
– Domestic and/or wild
animals can serve as
reservoirs and/or
vectors
 e.g., bovine TB
(Mycobacterium bovis)
Wildlife Diseases
• Interest from wildlife
management point-ofview:
– Density of wildlife
populations
– DD response?
– Red Grouse & strongylosis
(caused by
Trichostrongylus tenuis)
– Lack’s rebuttal [food supply
& weakened state of birds]
Wildlife Diseases
• Interest from wildlife
management pointof-view:
– Small populations,
threatened/endanger
ed spp.
Wildlife Diseases
• Interest from wildlife
management point-ofview:
– Small populations,
threatened/endangered
spp.
 1984 Patuxent Wildlife
Research Center, 7 of 39
whooping cranes (18% of
captive breeding flock) die
of possible insect-borne
virus
Wildlife Diseases
• Interest from wildlife
management point-ofview:
– Part of community
dynamics
 Newfoundland, lynx biting
caribou calves, transfer
Pasteurella multocida in
saliva via bites
 27% calf survival before
lynx removal
 63% calf survival after lynx
removal
Wildlife Diseases
• Wildlife
management
responses:
– Culling
 Stanislaus Nat’l
Forest (CA) 19241925, 22,000 mule
deer killed in
response to footand-mouth outbreak
in cattle
 10% of these
showed lesions
Wildlife Diseases
• Wildlife
management
responses:
– Monitor and “Clean
up”/Contain
 e.g., avian botulism
CWD
CWD
•
Captive and wild cervids
–
–
–
–
•
•
•
•
white-tailed deer
mule deer
elk
moose
First observed, 1967, Colorado
Division of Wildlife’s Research
Facility in Fort Collins, CO (initially
thought to be malnutrition)
1977 CWD determined to be TSE
(mule deer)
1981, 1st wild animal (elk) from
Rocky Mt. Nat’l Park, diagnosed
Models suggests may have been
present in free-ranging
populations of mule deer for more
than 40 years
CWD
• Susceptibility of other
cervids to CWD not
known
• Cattle and other
domestic livestock
appear to be resistant
to natural infection
(research continues)
• Privately owned cervid
facilities (POC) may
allow spread
USDA APHIS WS
• National Wildlife
Research Center
(NWRC)
• Congressional
appropriations for
research and
management of
CWD (and many
other conflict
issues)
Dr. Kurt VerCauteren
CWD in WI
• Discovered wild
deer in 2001/2002
• >700,000 deer
hunters
• Avg 460,000 deer
harvested
• Generates >$500
million retail
• ~$1 billion impact to
state’s economy
CWD in WI
• Discovered wild deer in
2001/2002
• Spent $40+ million
testing and drastically
reducing deer
populations since
• Initially planned to kill all
estimated 30,000 deer
in focal area
• Saskatchewan spent
$30+ million
CWD in WI
CWD in WI
CWD in WI
CWD in WI
CWD in WI
CWD in WI
• Surveillance program
to detect 1%
prevalence
• Difference in
age/gender
– 0.16% fawns +
– Increase prevalence
with age (faster in
males)
– 2-3% yearlings +
– 2+ yrs (M = 10%, F =
4-5% +)
CWD in Michigan
• Michigan : Michigan's First Case of Chronic Wasting Disease
Detected at Kent County Deer Breeding Facility
Date: August 25, 2008
Source: Michigan Department of Natural Resources
LANSING - The Michigan departments of Agriculture (MDA) and
Natural Resources (DNR) today confirmed the state's first case of
Chronic Wasting Disease (CWD) in a three-year old white-tailed
deer from a privately owned cervid (POC) facility in Kent County.
The state has quarantined all POC facilities, prohibiting the
movement of all - dead or alive - privately-owned deer, elk or moose.
Officials do not yet know how the deer may have contracted the
disease. To date, there is no evidence that CWD presents a risk to
humans.
CWD in Michigan
• Michigan : Tests of More Than 1,000 Deer Find No
More Cases of Chronic Wasting Disease
Date: October 07, 2008
Source: The Grand Rapids Press
Statewide, 1,095 deer have been tested, with 964 testing
clean and 131 awaiting results. More than 300 wild Kent
County deer have been tested and found to be clear of
chronic wasting disease after the highly contagious
disorder was found in one northern Kent County farmraised deer in August.
Approximately $1 million spent on testing