Lecture 5: Equine Encephalitis

Strains of equine encephalitis, by mortality

Eastern: 50-90%

Venezuelan: 50-75%

Western: 20-50%

General characteristics of EE

* aka sleeping sickness
* no cross immunity between strains
* horse is the dead end host
* zoonotic via birds

What animal is the EE reservoir

Birds

What animal is the EE vector

Mosquitos

EE incubation period

5 days - 2 weeks

How quickly does EE cause death

2-3 days

Clinical signs of EE

* pyrexia, precedes neuro by 1-2 days
* impaired vision
* irregular gait, aimless wandering, circling
* hyporeflexia, incoordination, head pressing
* yawning, drowsiness
* teeth grinding
* pendulous lower lip
* inability to swallow
* paralysis → death
* UNIQUE: affects brain

EE diagnosis

* clinical signs
* history
* vaccination
* seasonal incidence
* PCR/virus isolation
* paired serum titers

Major differentials when seeking EE diagnosis

Rabies, west Nile virus, equine protozoal myeloencephalitis

EE tx

* anti inflammatory
* antipyretics
* analgesic
* intensive care: fluids

EE prevention

* spring vaccination
* IM vaccine

EE control

* topical repellants
* fly sheets/mask
* drain stagnant water
* decrease pasture time during mosquito season
* sentinel chickens

Explain sentinel animals

An animal on the perimeter that has blood checked on a regular basis for a disease