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

E

A H

Good Health“In Balance”

A

H

Ex: InfluenzaAgent Increased

A

H

Ex: Tularemia, PlagueHost pop. increased

A

HA

H

Ex: Air Pollution-Environment upset & makes host more susceptible

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 Infectious (not contagious)

cold 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-of-view:– Domestic and/or wild

animals can serve as reservoirs and/or vectors

– Density of wildlife populations

Wildlife Diseases

• Interest from human health & safety point-of-view:– Domestic and/or wild

animals can serve as reservoirs and/or vectors

e.g., avian influenzaSince 2003, 393

human cases, 248 deaths (WHO)

Wildlife Diseases

• Interest from pet/domestic animal health & safety point-of-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-of-view:– 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 point-of-view:– Small populations,

threatened/endangered spp.

Wildlife Diseases

• Interest from wildlife management point-of-view:– 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-of-view:– 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:– CullingStanislaus Nat’l

Forest (CA) 1924-1925, 22,000 mule deer killed in response to foot-and-mouth outbreak in cattle

10% of these showed lesions

Wildlife Diseases• Wildlife

management responses:– Monitor and “Clean

up”/Containe.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, 2008Source: 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 farm-raised deer in August.

Approximately $1 million spent on testing