Equine - encephalitis Flashcards
1
Q
What is the structure of alphavirues (EEEV/WEEV/VEE)
A
- 11 kb (+) ssRNA
- enveloped with glycoproteins
2
Q
What are equine alphaviruses?
A
- characterized by CNS dysfunction and moderate to high mortality in horses
- Viruses genetically and antigenically distinct
- considerable antigenic diversity
3
Q
What is EEEV?
A
- Occurs in:
- Eastern Canada, States East of the Mississippi River
- AR, MN, SD, TX, MI, LA, MT,
- Caribbean islands
- Clinical disease can occur in horses, humans, alpacas, llamas, cattle, swine, cats and dogs
- Enzootic in birds along east coat
4
Q
What is the mortality rate of EEEV in humans?
A
30-70%
5
Q
can humans/horses transmit EEEV?
A
no dead-end-hosts
low level viremias insufficient vector transmission
6
Q
What is WEEV?
A
- Occurs in:
- western canada
- States west of the mississippi river
- Mexico and South america
- Associated with increased rainfall in early spring followed by warm temperatures
- Infrequent in US but circulates in wildlife
7
Q
Human mortality rate of WEEV
A
3-7%
8
Q
What is VEEV
A
- Occurs in South and Central America
- Not diagnosed in US for >40 years
- REPORTABLE
- associated with jungle/swampy areas
- all mammalian hosts capable of developing high-titer viremia for up to 5 days
9
Q
What makes VEEV different for EEEV/WEEV?
A
- enzootic in rodents (not birds)
- Horses and humans are NOT dead-end hosts - Amplify VEEV
10
Q
What is the human mortality rate of VEEV
A
- 10-35%
11
Q
What is the structure of Flaviviruses?
A
- 10kb (+) ssRNA
- Enveloped proteins
12
Q
What is WNV?
A
- Similar to EEEV/WEEV
- more widespread
- horses and humans dead end hosts
- birds are reservoirs
13
Q
What is the human mortality rate of WNV
A
3-5%
14
Q
What are the clinical findings of Equine Arboviral Encephalomyelitis Viruses? (EEEV, WEEV, VEEV, WNV)
A
- Clinical signs similar and nonspecific
- depression, reduced activity, fever, decreased appetite
- Infections may be subclinical
- Progression and severity of disease is different between viruses
- More: EEEV and VEEV
- Less: WEEV and WNV
- Neurologic signs typically occur 9-11 dpi
- may have shorter incubation with EEEV/VEEV (5dpi)
- “sleeping sickness”
15
Q
What are neurologic signs that are more common with EEEV and VEEV?
A
- Altered mentation, blindness, restlessness, hypersensitivity, head pressing, circling, dysphagia, irregular ataxic gait, paresis and paralysis, seizures and death
- symmetric ataxia affecting all limbs, progresses to quadriparesis
- Many progress to recumbency 12-18 hrs after onset of neurological signs
- death within 2-3 days of clinical onset (EEEV)