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What viruses belong to the Orbivirus genus (Reoviridae)?
- African Horse Sickness
- Blue Tongue
How is African Horse Sickness transmitted?
Culicoides spp (insect vector)
What are the four forms of African Horse Sickness (4)?
- Peracute (Pulmonary)
- Subacute Edematous (Cardiac)
- Acute (mixed)
- Horse sickness fever
What clinical signs are seen in the peracute (3-5 days incubation) form of African Horse Sickness (4)?
- Respiratory distress
- Spasmodic coughing
- Frothy, serofibrinous fluid exuding from the nostrils
In what animals is the peracute (pulmonary) form of african horse sickness seen in (2)?
- Completely susceptible animals with highly virulent virus strains
- Animals that are worked during the febrile stage of the disease
What clinical signs are seen in the subacute edematous (7-14 days incubation) form of African horse sickness(4)?
- Edematous swelling of neck, thorax, brisket, etc
- Petechial hemorrhage on ventral tongue
In what animals is the subacute (cardiac) form of african horse sickness seen in?
Animals infected with virus strains of low virulence
What are the clinical signs seen in the acute (mixed) form of african horse sickness(3)?
- Pulmonary/Edematous swellings
- Cardiac failure
- Death (80%)
What clinical signs are seen in horse sickness fever (5-14 days incubation) (5)?
In what animals is horse sickness fever seen in?
- Partially immune animals
- Resistant species such as donkeys and zebras
From what tissue is African horse sickness virus isolated from?
- Blood (Febrile stage)
- Lung, lymph nodes, and spleen (Necropsy)
How is African horse sickness diagnosed (4)?
- 2-6 day old mice inoculated intracerebrally
- Neutralization assays in mice or cell culture
How is African horse sickness prevented (2)?
- Live attenuated vaccine (may cause neurological signs)
- Inactivated vaccine not as good
What animals are the host for blue tongue virus (2)?
Where does Blue tongue virus replicate?
How is Blue tongue virus transmitted?
Culicoides spp. (insect vector)
What are the clinical signs of blue tongue infection (7)?
- Oral ulcers
- Purple-blue discoloration of tongue
- Coronary band hemorrhage
From what tissues is blue tongue virus isolated from?
Buffy coat during acute stage
How is blue tongue virus infection diagnosed (3)?
- Chicken embryos or cell culture
How is blue tongue virus infection prevented?
Attenuated vaccines (several disadvantages)
What are some disadvantages of the attenuated vaccine for blue tongue virus (3)?
- Associated with fetal deaths and cerebral abnormalities in sheep
- Emergence of genetic reassortments
- Culicoides spp could revert vaccine to virulent virus
What virus causes a fatal disease characterized by extensive hemorrhage in deer of the US and Canada?
Epizootic Hemorrhagic Disease
How is epizootic hemorrhagic disease transmitted?
Culicoides spp. (insect vector)
What clinical signs are seen in an epizootic hemorrhagic disease infection (6)?
- Loss of appetite
- Shock-like state
From what tissues is epizootic hemorrhagic disease virus isolated from (6)?
How is epizootic hemorrhagic disease diagnosed (2)?
- Cell culture
- Chicken embryo
What virus infects cattle, has two major genotypes (1 & 2), and two biotypes within each genotype (cytopathic and non-cytopathic)?
Bovine Viral Diarrhea
What viruses belong to the Flaviviridae family (6)?
- Bovine viral diarrhea
- Border disease virus
- Classical swine fever virus
- Japanese encephalitis virus
- St. Louis encephalitis virus
- West Nile virus
What are the two clinically different syndromes seen in Bovine Viral Diarrhea?
- Bovine viral diarrhea
- Mucosal disease
What form of bovine viral diarrhea is an acute epizootic infection of susceptible animals?
Bovine viral diarrhea
What form of bovine viral diarrhea is sporadic and occurs in persistently infected cattle in enzootically infected herds?
What are the clinical signs of a postnatal infection of bovine viral diarrhea in non-pregnant cattle (5)?
- Biphasic fever
- Nasal and ocular discharge
- Ulcers on muzzle, lips, oral cavity
What are the clinical signs of a bovine viral diarrhea infection in pregnant cows (3)?
- Embryonic death and resorption
- Congenital defects
What are the poss outcomes if a cow and fetus is infected with non-cytopathic bovine viral diarrhea virus during early pregnancy (3)?
- Cow becomes immune
- Fetus develops tolerance with no antibody response
- Super infection later on in life possible
What are the clinical signs associated with an acute persistent infection of bovine viral diarrhea in calves and mucosal disease (5)?
- Erosive lesions of the mouth and nares
- Death in a few days
What are the clinical signs associated with a chronic persistent infection of bovine viral diarrhea in calves and mucosal disease (4)?
- Intermittent diarrhea
- Gradual wasting
- Eruptive lesions on the skin of interdigital cleft
From what tissue is bovine viral diarrhea virus isolated from (2)?
- Nasal swab and tissue
How is bovine viral diarrhea infection diagnosed (4)?
- Viral RNA detection in tissues
- Detection of antigens in tissue
- Four fold rise in antibody titer in paired samples over 2-3 weeks will determine recent infection
- Immunohistochemistry test
How is bovine viral diarrhea infection prevented (2)?
- Live and attenuated vaccines
- Remove positive animals from herd
What disease is considered a congenital disease in lambs that is the cause of abnormal (hairy) wool growth, tremors, and can also infect cattle and goats?
Border Disease (HairyShaker disease)
If a sheep is infected with Border disease virus during the first 10-30 days of gestations, what may happen?
Fetal death (expulsion, resorption, mummification)
If a sheep is infected with Border disease virus after 80 days of gestation, what may happen?
Viral clearance without disease
What are some pathological lesions associated with border disease in newborn lambs (5)?
- Congenital tremors
- Necrosis of affected brain
- Cerebellar dysplasia
How is Border disease diagnosed?
Detect antigen by immunohistochemical methods in tissues of lambs
How is Border disease prevented?
BVDV vaccines are used sometimes
What are the different viruses that cause equine encephalitis?
- Eastern equine encephalitis
- Western equine encephalitis
- Venezuelan equine encephalitis
Which animals are dead-end hosts for EEE, WEE, VEE?
What is the natural reservoir for EEE, WEE, VEE (2)?
What are the different fatality rates for EEE, WEE, VEE?
- EEE (50-90%)
- WEE (20-40%)
- VEE (50-80%)
What are the clinical signs of equine encephalitidies (8)?
- Impaired vision
- Teeth grinding
- Convulsions and death
How does EEE, WEE or VEE viruses enter the host?
How is equine encephalitidies diagnosed (9)?
- Clinical signs/Location of horse/Season
- Virus isolation from brain
- Suckling mouse
- Cell culture
- Paired serum samples
- Complement fixation test