Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
11 Cards in this Set
- Front
- Back
West Nile Virus: Etiology
|
1) enveloped, + strand RNA
2) flaviviridae, genus flavivirus 3) highly pathogenic for horses and birds |
|
WNV: Transmission
|
1) mosquitoes to spread it among birds
2) Different mosquitoes to spread virus from birds to mammals |
|
WNV: Susceptible species
|
1) mosquitoes: replicates in intestine and salivary glands; small percentage of mosquitoes in an anedmic area actually carry the virus
2) Birds: fatal in crows, blue jays, ravens; high level of viremia for 1-4 days 3) Horses 4) Humans: <1% get severe clinical signs; if severe clinical signs develop after an incubation period of 3-15 days, fatality rate is 3-15% 5) recentaly, dogs and squirrels 6) Serological evidence of infection in other species |
|
WNV 2007
|
MT and CA had highest number of equine WNV
|
|
Clinical signs
|
1) Birds: corvids most susceptile, acute clinical signs, birds usually found dead and submitted for testing
2) Horses: mostly seen in older horses, acute onset ataxia, weakness, paresis of hind legs, paraparesis, progressing to tetraplegia and recumbency, low-grade fever or no fever, marked hypmetria, muscle fasiculations (common in horses). Less common signs: anisiocoria, slow PLR, seizure, head tremors, lip twitching, tongue paralysis, hypersensitivity to ligh/sound, somnolence, falling to knees 3) Humans: subclinical, fever, meningoencephalitis |
|
Lesions
|
1) Birds: heart muscle, kidney, brain
2) Horses: Brian-- nonsuppurative encephalomyelitis, perivascular cuffs, glial nodules and focal gliosis in the grey matter; Spinal cord-- non-suppurative inflam, possible neuronal degeneration, neuronophagia, gliosis |
|
Diagnosis
|
1) clinical signs
2) gross and histo lesions 3) virus isolation-- need BSL-3 lab 4) IHC-- don't use in horses 5) IgM capture ELISA 6) RT-PCR-- fresh (BSL-3) or formalin fixed tissue (not as good) 7) IgG ELISA (not used much) 8) Plaque reduction neutralization test (not used) |
|
WNV diagnosis in dead horses
|
1) submission of heads or whole bodies to DCPAH for necropsy
2) MDA will arrange for transportation if necessary |
|
Other testing of live equine suspects
|
1) IgG ELISA: screening test for previous exposure (vacc or natural)--NOT USED
2) VN: determines Ab titer. Most common for horses |
|
Control
|
1) mosquito control (reduce breeding sites)
2) limit exposure ot mosquitoes 3) supportive therapy 4) prevention of self-inflicted injuries in horses |
|
Prevention
|
1) inactivated vaccine for horses: Primary series-- two doses IM, 3-6 wks apart; yearly booster
2) vector vaccine by Merial. canarypox vector 3)intervet-- vector vacc w/ flavi vector (1 yr immunity w/ 1 dose) |