Wildlife Diseases Flashcards
Why are wildlife diseases important?
Threat to native wildlife populations
Impacts on domestic animals
Zoonotic potential
Economic importance
Wildlife diseases of importance in VA:
Rabies
Canine Distemper
Hemorrhagic Disease
Chronic Wasting Disease
White nose syndrome (bats)
Avian pox
Duck plague
Avian influenza
Avian cholera
What type of virus is rabies?
Single stranded RNA virus
Family: Rhabdoviridae
Genus: Lyssavirus
Which states have reported the most number of cases of wildlife rabies?
NC, NY, NJ, TX, VA
Which animal accounts for the largest proportion of human cases of Rabies?
Bats (92%)
What are the clinical signs of “dumb” rabies?
Aimless wandering, lethargy, incoordination, weakness in hind legs, paralysis, loss of awareness
What are clinical signs of “vicious” rabies?
Vicious attacks and self mutilation
Both forms of rabies ultimately end in:
Convulsions, Coma, and Death
In VA, which animals account for the most rabies cases?
Raccoons (47%)
Skunks (26%)
Foxes (10%)
Bats (4%)
Rodents/Lagomorphs (0.9%)
Domestic animals (dogs, cats, cows, horses) (3.5%)
What is the general incubation period of Rabies?
1-3 months, but can vary
Diagnosis of Rabies?
Post-mortem examination of brain tissue by local health department
Histopath of brain my reveal nonsupparative encephalitis and Negri bodies
REPORTABLE
Control of Rabies?
Rabies vaccines in domestic animals!!
Oral rabies vaccine developed to immunize free ranging carnivores that consume vaccine laden baits
Etiology of Canine Distemper?
Genus: Morbillivirus
Family: Paramyxoviridae
Attacks epithelial cells of resp tract, GI tract, eyes
Clinical Signs of Canine Distemper?
Resp: Dyspnea, coughing, sneezing, catarrhal or purulent ocular or nasal discharge
GI: Diarrhea
Neuro: Similar to Rabies (convulsions, tremors, chewing fits, loss of fear)
Dermatologic: Proliferation of foot pad epithelium
What is the transmission and pathogenesis of canine distemper?
Direct contact or aerosol of ocular and nasal secretions, as well as urine
Virus does NOT survive in environment
Incubation 14-18 days (dogs)
Encephalitis and death in 2-4 weeks in wildlife
No treatment
Diagnosis of canine distemper?
Histopath: intranuclear and intracytoplasmic inclusion bodies
Specimens: brain, lung, bladder, gallbladder, liver, pancreas, foot pad, stomach
Virus isolation
FAT (air dried ocular swabs)
What is the significance of canine distemper?
Not a major HUMAN public health concern
Can be confused with rabies due to very similar clinical signs
Some wildlife may have concurrent infections of rabies and distemper
What is the most important infectious disease of white tailed deer in the U.S.?
Hemorrhagic disease
Etiology of hemorrhagic disease?
Caused by two closely related but distinct orbiviruses
Epizootic hemorrhagic disease (EHD) and bluetongue virus (BT)
Clinical signs of hemorrhagic disease?
*Fever, depression, oral cyanosis, pulmonary edema, resp distress, edema of head, neck, tongue, conjunctiva; hemorrhage at base of pulmonary artery
*Lameness
*Sloughing of hoof walls and secondary infections
*Weight loss, emaciation
*Death in 1-3 days
Transmission of hemmorhagic disease?
Biting midges, Culicoides sp, especially C. variipennis
Mortality of hemorrhagic disease?
Late summer to early fall
Stops with freezing temps
What would be a general presentation for an animal with hemorrhagic disease out in the field?
Recumbent, reluctant to move, close to water source
In VA, where is there a higher prevalence of hemorrhagic disease?
Eastern coast, rarely west of Blue Ridge Mountains
Significance of hemorrhagic disease?
Major infection of white tailed deer
Dramatic local population decline in white tailed deer
DDX: resembles FMD, Rinderpest, Heartwater dz
No public health significance
What are the general characteristics of “Chronic Wasting Disease?”
Emerging wildlife disease in VA
Progressive neuro disease ultimately results in death
Belongs to transmissible spongiform encephalopathies (TSEs)
What are TSEs?
Diseases caused by prions that accumulate in neurons
Spongiform degeneration of CNS
What are the hosts of CWD?
White tailed deer, Elk, mule deer, black-tailed deer, moose
Transmission of CWD?
Direct, from animal to animal, most important
Indirect from contaminated food or environment also possible (importance unknown)
Prions remain in environment for years
Incubation period of CWD?
Incubation period 12-18 months up to 3-5 years
Clinical signs of CWD?
Staggering/standing with poor posture, emaciation, poor body condition (all in later stages)
Diagnosis of CWD?
Examining obex of medulla oblongata & retropharyngeal lymph nodes for prions
ELISA test for free-ranging white tail deer
Is CWD transmissible to humans?
No current evidence